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Sample records for dynamic spectrum access

  1. Decision Analysis of Dynamic Spectrum Access Rules

    Energy Technology Data Exchange (ETDEWEB)

    Juan D. Deaton; Luiz A. DaSilva; Christian Wernz

    2011-12-01

    A current trend in spectrum regulation is to incorporate spectrum sharing through the design of spectrum access rules that support Dynamic Spectrum Access (DSA). This paper develops a decision-theoretic framework for regulators to assess the impacts of different decision rules on both primary and secondary operators. We analyze access rules based on sensing and exclusion areas, which in practice can be enforced through geolocation databases. Our results show that receiver-only sensing provides insufficient protection for primary and co-existing secondary users and overall low social welfare. On the other hand, using sensing information between the transmitter and receiver of a communication link, provides dramatic increases in system performance. The performance of using these link end points is relatively close to that of using many cooperative sensing nodes associated to the same access point and large link exclusion areas. These results are useful to regulators and network developers in understanding in developing rules for future DSA regulation.

  2. Comparison of RF spectrum prediction methods for dynamic spectrum access

    Science.gov (United States)

    Kovarskiy, Jacob A.; Martone, Anthony F.; Gallagher, Kyle A.; Sherbondy, Kelly D.; Narayanan, Ram M.

    2017-05-01

    Dynamic spectrum access (DSA) refers to the adaptive utilization of today's busy electromagnetic spectrum. Cognitive radio/radar technologies require DSA to intelligently transmit and receive information in changing environments. Predicting radio frequency (RF) activity reduces sensing time and energy consumption for identifying usable spectrum. Typical spectrum prediction methods involve modeling spectral statistics with Hidden Markov Models (HMM) or various neural network structures. HMMs describe the time-varying state probabilities of Markov processes as a dynamic Bayesian network. Neural Networks model biological brain neuron connections to perform a wide range of complex and often non-linear computations. This work compares HMM, Multilayer Perceptron (MLP), and Recurrent Neural Network (RNN) algorithms and their ability to perform RF channel state prediction. Monte Carlo simulations on both measured and simulated spectrum data evaluate the performance of these algorithms. Generalizing spectrum occupancy as an alternating renewal process allows Poisson random variables to generate simulated data while energy detection determines the occupancy state of measured RF spectrum data for testing. The results suggest that neural networks achieve better prediction accuracy and prove more adaptable to changing spectral statistics than HMMs given sufficient training data.

  3. A Survey on Dynamic Spectrum Access Techniques for Cognitive Radio

    CERN Document Server

    Garhwal, Anita

    2012-01-01

    Cognitive radio (CR) is a new paradigm that utilizes the available spectrum band. The key characteristic of CR system is to sense the electromagnetic environment to adapt their operation and dynamically vary its radio operating parameters. The technique of dynamically accessing the unused spectrum band is known as Dynamic Spectrum Access (DSA). The dynamic spectrum access technology helps to minimize unused spectrum bands. In this paper, main functions of Cognitive Radio (CR) i.e. spectrum sensing, spectrum management, spectrum mobility and spectrum sharing are discussed. Then DSA models are discussed along with different methods of DSA such as Command and Control, Exclusive-Use, Shared Use of Primary Licensed User and Commons method. Game-theoretic approach using Bertrand game model, Markovian Queuing Model for spectrum allocation in centralized architecture and Fuzzy logic based method are also discussed and result are shown.

  4. Radio resource allocation and dynamic spectrum access

    CERN Document Server

    Benmammar , Badr

    2013-01-01

    We are currently witnessing an increase in telecommunications norms and standards given the recent advances in this field. The increasing number of normalized standards paves the way for an increase in the range of services available for each consumer. Moreover, the majority of available radio frequencies have already been allocated. This explains the emergence of cognitive radio (CR) - the sharing of the spectrum between a primary user and a secondary user.In this book, we will present the state of the art of the different techniques for spectrum access using cooperation and competit

  5. CMOS RF Transceiver condiderations for Dynamic Spectrum Access

    NARCIS (Netherlands)

    Oude Alink, M.S.; Klumperink, E.A.M.; Kokkeler, A.B.J.; Smit, G.J.M.; Nauta, B.

    2012-01-01

    Cognitive Radio (CR), and in particular dynamic spectrum access (DSA), promises a much more efficient use of the spectrum by opportunistically using available frequencies. This asks for specific functionality, like spectrum sensing and frequency-agile transmission and reception. We will show that th

  6. Supporting Dynamic Spectrum Access in Heterogeneous LTE+ Networks

    Energy Technology Data Exchange (ETDEWEB)

    Luiz A. DaSilva; Ryan E. Irwin; Mike Benonis

    2012-08-01

    As early as 2014, mobile network operators’ spectral capac- ity is expected to be overwhelmed by the demand brought on by new devices and applications. With Long Term Evo- lution Advanced (LTE+) networks likely as the future one world 4G standard, network operators may need to deploy a Dynamic Spectrum Access (DSA) overlay in Heterogeneous Networks (HetNets) to extend coverage, increase spectrum efficiency, and increase the capacity of these networks. In this paper, we propose three new management frameworks for DSA in an LTE+ HetNet: Spectrum Accountability Client, Cell Spectrum Management, and Domain Spectrum Man- agement. For these spectrum management frameworks, we define protocol interfaces and operational signaling scenar- ios to support cooperative sensing, spectrum lease manage- ment, and alarm scenarios for rule adjustment. We also quan- tify, through integer programs, the benefits of using DSA in an LTE+ HetNet, that can opportunistically reuse vacant TV and GSM spectrum. Using integer programs, we consider a topology using Geographic Information System data from the Blacksburg, VA metro area to assess the realistic benefits of DSA in an LTE+ HetNet.

  7. Admission Control and Interference Management in Dynamic Spectrum Access Networks

    Directory of Open Access Journals (Sweden)

    Jorge Martinez-Bauset

    2010-01-01

    Full Text Available We study two important aspects to make dynamic spectrum access work in practice: the admission policy of secondary users (SUs to achieve a certain degree of quality of service and the management of the interference caused by SUs to primary users (PUs. In order to limit the forced termination probability of SUs, we evaluate the Fractional Guard Channel reservation scheme to give priority to spectrum handovers over new arrivals. We show that, contrary to what has been proposed, the throughput of SUs cannot be maximized by configuring the reservation parameter. We also study the interference caused by SUs to PUs. We propose and evaluate different mechanisms to reduce the interference, which are based on simple spectrum access algorithms for both PUs and SUs and channel repacking algorithms for SUs. Numerical results show that the reduction can be of one order of magnitude or more with respect to the random access case. Finally, we propose an adaptive admission control scheme that is able to limit simultaneously the forced termination probability of SUs and what we define as the probability of interference. Our scheme does not require any configuration parameters beyond the probability objectives. Besides, it is simple to implement and it can operate with any arrival process and distribution of the session duration.

  8. Game-theoretic interference coordination approaches for dynamic spectrum access

    CERN Document Server

    Xu, Yuhua

    2016-01-01

    Written by experts in the field, this book is based on recent research findings in dynamic spectrum access for cognitive radio networks. It establishes a game-theoretic framework and presents cutting-edge technologies for distributed interference coordination. With game-theoretic formulation and the designed distributed learning algorithms, it provides insights into the interactions between multiple decision-makers and the converging stable states. Researchers, scientists and engineers in the field of cognitive radio networks will benefit from the book, which provides valuable information, useful methods and practical algorithms for use in emerging 5G wireless communication.

  9. Primary User Traffic Estimation for Dynamic Spectrum Access

    CERN Document Server

    Gabran, Wesam; Pawełczak, Przemysław; Cabric, Danijela

    2012-01-01

    Accurate estimation of licensed channel Primary User's (PU) temporal statistics is important for Dynamic Spectrum Access (DSA) systems. With accurate estimation of the mean duty cycle, u, and the mean off- and on-times of PUs, DSA systems can more efficiently assign PU resources to its subscribers, thus, increasing channel utilization. This paper presents a mathematical analysis of the accuracy of estimating u, as well as the PU mean off- and on-times, where the estimation accuracy is expressed as the mean squared estimation error. The analysis applies for the traffic model assuming exponentially distributed PU off- and on-times, which is a common model in traffic literature. The estimation accuracy is quantified as a function of the number of samples and observation window length, hence, this work provides guidelines on traffic parameters estimation for both energy-constrained and delay-constrained applications. For estimating u, we consider uniform, non-uniform, and weighted sample stream averaging, as well...

  10. Dynamic Spectrum Access in Cognitive Radio Networks with RF Energy Harvesting

    OpenAIRE

    Lu, Xiao; Wang,Ping; Dusit, Niyato; Ekram, Hossain

    2014-01-01

    Spectrum efficiency and energy efficiency are two critical issues in designing wireless networks. Through dynamic spectrum access, cognitive radios can improve the spectrum efficiency and capacity of wireless networks. On the other hand, radio frequency (RF) energy harvesting has emerged as a promising technique to supply energy to wireless networks and thereby increase their energy efficiency. Therefore, to achieve both spectrum and energy efficiencies, the secondary users in a cognitive rad...

  11. 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

  12. 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.

  13. 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.

  14. Setting scene for TV white spaces and dynamic spectrum access in South Africa

    CSIR Research Space (South Africa)

    Masonta, MT

    2012-05-01

    Full Text Available In this paper an overview of the TV white space technology and dynamic spectrum access is presented with the aim of improving the capacity of wireless broadband connectivity of communities in emerging markets. The paper proposes that large chunks...

  15. Evaluation of Spectrum Usage for GSM band in Indoor and Outdoor Scenario for Dynamic Spectrum Access

    DEFF Research Database (Denmark)

    Patil, Kishor P.; Barge, Snehal; Skouby, Knud Erik

    2013-01-01

    measurement results of GSM band including statistical as well as spectral occupancy details obtained from measurement campaign conducted in Pune, India for indoor and outdoor scenarios. The results can be further used as an input for spectrum regulator for considering Cognitive Radio (CR) operation in GSM...

  16. 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.

  17. Cognitive radio policy and regulation techno-economic studies to facilitate dynamic spectrum access

    CERN Document Server

    Holland, Oliver

    2014-01-01

    This book offers a timely reflection on how the proliferation of advanced wireless communications technologies, particularly cognitive radio (CR) can be enabled by thoroughly-considered policy and appropriate regulation. It looks at the prospects of CR from the divergent standpoints of technological development and economic market reality. The book provides a broad survey of various techno-economic and policy aspects of CR development, and provides the reader with an understanding of the complexities involved as well as a toolbox of possible solutions to enable the evolutionary leap towards successful implementation of disruptive CR technology or indeed any other novel wireless technologies. Cognitive Radio Policy and Regulation showcases the original ideas and concepts introduced into the field of CR and dynamic spectrum access policy over nearly four years of work within COST Action IC0905 TERRA, a think-tank with participants from more than 20 countries. The book’s subject matter includes: • deploymen...

  18. The Effects of a Dynamic Spectrum Access Overlay in LTE-Advanced Networks

    Energy Technology Data Exchange (ETDEWEB)

    Juan D. Deaton; Ryan E. lrwin; Luiz A. DaSilva

    2011-05-01

    As early as 2014, wireless network operators spectral capacity will be overwhelmed by a data tsunami brought on by new devices and applications. To augment spectral capacity, operators could deploy a Dynamic Spectrum Access (DSA) overlay. In the light of the many planned Long Term Evolution (LTE) network deployments, the affects of a DSA overlay have not been fully considered into the existing LTE standards. Coalescing many different aspects of DSA, this paper develops the Spectrum Accountability (SA) framework. The SA framework defines specific network element functionality, protocol interfaces, and signaling flow diagrams for LTE to support service requests and enforce rights of responsibilities of primary and secondary users, respectively. We also include a network simulation to quantify the benefits of using DSA channels to augment capacity. Based on our simulation we show that, network operators can benefit up to %40 increase in operating capacity when sharing DSA bands to augment spectral capacity. With our framework, this paper could serve as an guide in developing future LTE network standards that include DSA.

  19. A new bio-inspired, population-level approach to the socioeconomic evolution of dynamic spectrum access services

    Science.gov (United States)

    Horvath, Denis; Gazda, Juraj; Brutovsky, Branislav

    Evolutionary species and quasispecies models provide the universal and flexible basis for a large-scale description of the dynamics of evolutionary systems, which can be built conceived as a constraint satisfaction dynamics. It represents a general framework to design and study many novel, technologically contemporary models and their variants. Here, we apply the classical quasispecies concept to model the emerging dynamic spectrum access (DSA) markets. The theory describes the mechanisms of mimetic transfer, competitive interactions between socioeconomic strata of the end-users, their perception of the utility and inter-operator switching in the variable technological environments of the operators offering the wireless spectrum services. The algorithmization and numerical modeling demonstrate the long-term evolutionary socioeconomic changes which reflect the end-user preferences and results of the majorization of their irrational decisions in the same manner as the prevailing tendencies which are embodied in the efficient market hypothesis.

  20. Estimation and Coordination of Sequence Patterns for Frequency Hopping Dynamic Spectrum Access Networks

    Science.gov (United States)

    2014-03-27

    than one node. A separate effort demonstrated applicability of these algorithms via hardware implementation on the GNU radio test bed [30]. It also...Spectrum Company showed in a survey of Radio Frequency (RF) bands that underutilization of spectrum has resulted from current frequency management...division based protocols where radios always share their environment information. Larger networks, on the other hand, function best when a dispute-based

  1. A localized cooperative wideband spectrum sensing for dynamic access of TV bands using RF sensor networks

    KAUST Repository

    Mirza, Mohammed

    2011-07-01

    In this paper we address and simulate a Radio Frequency (RF) sensor network for a cooperative spectrum sensing and localization scheme. The proposed method integrates a Wavelet based Multi-Resolution Spectrum Sensing (MRSS), an N-bit hard combination technique for cooperative decision making and a Received Signal Strength (RSS) based localization algorithm to detect the availability of frequency bands and the location of the usable base station. We develop an N-bit hard combination technique and compare its performance to a traditionally used 2-bit hard combination for cooperative sensing. The key idea is to design a novel RF sensor network based cooperative wideband spectrum sensing and localization scheme by using a wavelet based Multi-Resolution Spectrum Sensing (MRSS) and Received Signal Strength (RSS) Localization techniques which were originally proposed for cognitive radio applications. The performance evaluations are also done to show the different detection accuracies for varying parameters such as number of sensor nodes, Signal to Noise Ratios (SNR) and number of averaged Power Spectral Densities (PSD). The proposed scheme improves the problems of shadowing, fading and noise. In addition, the RSS based localization technique was shown to be an acceptable means of estimating the position of the available transmitter. © 2011 IEEE.

  2. Dynamic spectrum auction in wireless communication

    CERN Document Server

    Chen, Yanjiao

    2015-01-01

    This brief explores current research on dynamic spectrum auctions, focusing on fundamental auction theory, characteristics of the spectrum market, spectrum auction architecture and possible auction mechanisms. The brief explains how dynamic spectrum auctions, which enable new users to gain spectrum access and existing spectrum owners to obtain financial benefits, can greatly improve spectrum efficiency by resolving the artificial spectrum shortage. It examines why operators and users face significant challenges due to specialty of the spectrum market and the related requirements imposed on the auction mechanism design. Concise and up-to-date, Dynamic Spectrum Auction in Wireless Communication is designed for researchers and professionals in computer science or electrical engineering. Students studying networking will also find this brief a valuable resource.

  3. A Cognitive Agent for Spectrum Monitoring and Informed Spectrum Access

    Science.gov (United States)

    2017-06-01

    ARL-TR-8041 ● JUNE 2017 US Army Research Laboratory A Cognitive Agent for Spectrum Monitoring and Informed Spectrum Access by...needed. Do not return it to the originator. ARL-TR-8041 ● JUNE 2017 US Army Research Laboratory A Cognitive Agent for Spectrum...should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of

  4. Removal of cyclic prefix in Adaptive Non-Contiguous OFDM for Dynamic Spectrum Access using DWT and WT

    OpenAIRE

    Saket kumar; Puspraj Tanwar

    2012-01-01

    Spectrum has valuable resource in wireless communication. In wireless communication some spectrum is waste due to uses of cyclic prefix (cp) in FFT multicarrier sampling. In place of FFT used DFT and wavelet transform function for removal of cyclic prefix. Wavelet based OFDM, particularly using DWT and WPT-OFDM as situations for Fourier- based OFDM with the focus on impulse noise effects. We begin by constructing the models of the inverse and forward transforms. We explain in detail each mode...

  5. 基于POMDP的感知无线电动态频谱接入设计%Design of cognitive radio and dynamic spectrum access based on POMDP

    Institute of Scientific and Technical Information of China (English)

    卢晓珍; 蒋嘉轩

    2016-01-01

    动态频谱接入(Dynamic Spectrum Access,DSA)技术是感知无线电的关键技术之一,由于受能量及硬件条件限制,提出了基于部分可观察马尔可夫决策过程(Partially Observable Markov Decision Processes,POMDP)的动态频谱接入模型.通过把系统建模为部分可观测马尔可夫决策过程,文章探讨了最优和降低复杂度的次优信道感知和接入策略.仿真结果表明该算法获得的信道回报要优于传统的随机接入算法.

  6. System of vehicular dynamic spectrum access via queuing theory%基于排队论的车辆动态频谱接入系统研究

    Institute of Scientific and Technical Information of China (English)

    张伟; 刘南杰; 赵海涛

    2014-01-01

    This paper discusses dynamic spectrum access technology in the area of vehicular communication network , proposing a model of vehicular dynamic spectrum access over vacant TV channels. This model divides the communication needs of users for emergency and general service requests, and constructs the Markov chain model to analysis the service processes of them. As a result, an analytical model to meet different needs is constructed. The simulation results show that there is a significant reduction in the average queue waiting time with the increases number of available channels, and the average waiting time and queue length of the emergency service requests are far smaller than the general service requests.%将动态频谱接入技术引入到车辆通信网络中,提出了一种使用空闲广播电视信道进行车辆动态频谱接入的模型。该模型将用户通信需求分为紧急和普通服务请求,构建马尔科夫链分析其服务过程,得到了能够满足不同需求的分析模型。仿真结果表明,该模型能准确分析车辆动态频谱接入的过程,当空闲信道数增加时平均等待时间减少,紧急服务请求的平均等待时间和平均队列长度都远小于普通服务请求。

  7. Removal of cyclic prefix in Adaptive Non-Contiguous OFDM for Dynamic Spectrum Access using DWT and WT

    Directory of Open Access Journals (Sweden)

    Saket kumar

    2012-09-01

    Full Text Available Spectrum has valuable resource in wireless communication. In wireless communication some spectrum is waste due to uses of cyclic prefix (cp in FFT multicarrier sampling. In place of FFT used DFT and wavelet transform function for removal of cyclic prefix. Wavelet based OFDM, particularly using DWT and WPT-OFDM as situations for Fourier- based OFDM with the focus on impulse noise effects. We begin by constructing the models of the inverse and forward transforms. We explain in detail each model and study the BER performance in two scenarios when varying the Poisson recurrence parameter a from small to large. The wavelet based SOFDM (DWT-SOFDM and WPT-SOFDM are assumed to have other normal bases and perfect reconstruction properties. Results show that a large values of limits the impact of impulsive noise on the system. We also found that the WPT-SOFDM platform is superior in BER to others.

  8. Cyclostationary Beacon for Assisting Spectrum Sensing in Opportunistic Spectrum Access

    Directory of Open Access Journals (Sweden)

    Thomas Kaiser

    2011-03-01

    Full Text Available Cognitive radio is a promising solution to the problem of spectrum scarcity by means of allowing secondary radio networks access the spectrum opportunistically. One of the most important issues in cognitive radio is how to detect existing over-the-air signals reliably. Not a few literatures have reported that signals could be detected via their inherent or embedded properties. However, this approach may not be reliable and flexible enough for all kinds of signals with different modulation types. In this paper, we propose a type of multitone beacon signal carrying cyclostationary signatures, which is able to enhance the reliability and efficiency of signal detection at low cost of spectrum overhead. This beacon not only can indicate the presence or absence of user signal but also can reveal some other information helpful to opportunistic spectrum access through the information bits carried on its cyclostationary signatures. It could be applied to device/network identification, indication of spectrum allocation and spectrum rendezvous, both for primary and secondary users. Based on our previous work reported in [1], the generation and detection algorithm of the beacon signal are extended with improved spectral efficiency. Performance is discussed with both computer simulation and testbed validation.

  9. Removal of cyclic prefix in Adaptive Non-Contiguous OFDM for Dynamic Spectrum Access using DWT and WT

    Directory of Open Access Journals (Sweden)

    Saket kumar

    2012-09-01

    Full Text Available Spectrum has valuable resource in wirelesscommunication. In wireless communication somespectrum is waste due to uses of cyclic prefix (cp inFFT multicarrier sampling. In place of FFT usedDFT and wavelet transform function for removal ofcyclic prefix. Wavelet based OFDM, particularlyusing DWT and WPT-OFDM as situations forFourier- based OFDM with the focus on impulsenoise effects. We begin by constructing the modelsof the inverse and forward transforms. We explainin detail each model and study the BERperformance in two scenarios when varying thePoisson recurrence parameter a from small to large.The wavelet based SOFDM (DWT-SOFDM andWPT-SOFDM are assumed to have other normalbases and perfect reconstruction properties. Resultsshow that a large values of limits the impact ofimpulsive noise on the system. We also found thatthe WPT-SOFDM platform is superior in BER toothers.

  10. Efficient Online Learning for Opportunistic Spectrum Access

    CERN Document Server

    Dai, Wenhan; Krishnamachari, Bhaskar

    2011-01-01

    The problem of opportunistic spectrum access in cognitive radio networks has been recently formulated as a non-Bayesian restless multi-armed bandit problem. In this problem, there are N arms (corresponding to channels) and one player (corresponding to a secondary user). The state of each arm evolves as a finite-state Markov chain with unknown parameters. At each time slot, the player can select K < N arms to play and receives state-dependent rewards (corresponding to the throughput obtained given the activity of primary users). The objective is to maximize the expected total rewards (i.e., total throughput) obtained over multiple plays. The performance of an algorithm for such a multi-armed bandit problem is measured in terms of regret, defined as the difference in expected reward compared to a model-aware genie who always plays the best K arms. In this paper, we propose a new continuous exploration and exploitation (CEE) algorithm for this problem. When no information is available about the dynamics of th...

  11. Dynamic Spectrum Sharing among Femtocells

    DEFF Research Database (Denmark)

    Da Costa, Gustavo Wagner Oliveira

    2012-01-01

    The ever-growing demand for mobile broadband is leading to an imminent spectrum scarcity. In order to cope with such situation dynamic spectrum sharing and the widespread deployment of small cells (femtocells) are promising solutions. Delivering such a view is not short of challenges. Massive dep...

  12. 75 FR 81558 - Promoting More Efficient Use of Spectrum Through Dynamic Spectrum Use Technologies

    Science.gov (United States)

    2010-12-28

    ... COMMISSION 47 CFR Part 5 Promoting More Efficient Use of Spectrum Through Dynamic Spectrum Use Technologies... access radios and techniques can promote more intensive and efficient use of the radio spectrum, and the potential that these technological innovations have for enabling more effective management of...

  13. Smart radio: spectrum access for first responders

    Science.gov (United States)

    Silvius, Mark D.; Ge, Feng; Young, Alex; MacKenzie, Allen B.; Bostian, Charles W.

    2008-04-01

    This paper details the Wireless at Virginia Tech Center for Wireless Telecommunications' (CWT) design and implementation of its Smart Radio (SR) communication platform. The CWT SR can identify available spectrum within a pre-defined band, rendezvous with an intended receiver, and transmit voice and data using a selected quality of service (QoS). This system builds upon previous cognitive technologies developed by CWT for the public safety community, with the goal of providing a prototype mobile communications package for military and public safety First Responders. A master control (MC) enables spectrum awareness by characterizing the radio environment with a power spectrum sensor and an innovative signal detection and classification module. The MC also enables spectrum and signal memory by storing sensor results in a knowledge database. By utilizing a family radio service (FRS) waveform database, the CWT SR can create a new communication link on any designated FRS channel frequency using FM, BPSK, QPSK, or 8PSK modulations. With FM, it supports analog voice communications with legacy hand-held FRS radios. With digital modulations, it supports IP data services, including a CWT developed CVSD-based VoIP protocol. The CWT SR coordinates spectrum sharing between analog primary users and digital secondary users by applying a simple but effective channel-change protocol. It also demonstrates a novel rendezvous protocol to facilitate the detection and initialization of communications links with neighboring SR nodes through the transmission of frequency-hopped rendezvous beacons. By leveraging the GNU Radio toolkit, writing key modules entirely in Python, and utilizing the USRP hardware front-end, the CWT SR provides a dynamic spectrum test bed for future smart and cognitive radio research.

  14. Scheduling Heterogeneous Wireless Systems for Efficient Spectrum Access

    Directory of Open Access Journals (Sweden)

    Liao Shenghui

    2010-01-01

    Full Text Available The spectrum scarcity problem emerged in recent years, due to unbalanced utilization of RF (radio frequency bands in the current state of wireless spectrum allocations. Spectrum access scheduling addresses challenges arising from spectrum sharing by interleaving the channel access among multiple wireless systems in a TDMA fashion. Different from cognitive radio approaches which are opportunistic and noncollaborative in general, spectrum access scheduling proactively structures and interleaves the channel access pattern of heterogeneous wireless systems, using collaborative designs by implementing a crucial architectural component—the base stations on software defined radios (SDRs. We discuss our system design choices for spectrum sharing from multiple perspectives and then present the mechanisms for spectrum sharing and coexistence of GPRS+WiMAX and GPRS+WiFi as use cases, respectively. Simulations were carried out to prove that spectrum access scheduling is an alternative, feasible, and promising approach to the spectrum scarcity problem.

  15. A Three Stage Market Competition-based Dynamic Game of Spectrum Access Algorithm%市场竞争下的三阶段动态博弈频谱接入算法

    Institute of Scientific and Technical Information of China (English)

    赵莎莎; 朱琦; 朱洪波

    2012-01-01

    A three stage market competition-based dynamic game of spectrum access algorithm is proposed by using a two-layer dynamic spectrum access network model. Backward induction and Bertrand game theory are adopted to solve the spectrum access problem. Two duopoly mobile virtual operators (MVNO) determine the amounts of the spectrum in succession and attracts the secondary end users by the price. The end users make their spectrum access options based on the heterogeneous preference over the rates and prices. The accuracy and stability of the algorithm has been analyzed theoretically and certificated by the existence of the unique Nash equilibrium. The simulation results show that the MVNOs could make investment optimally, pricing decisions flexibly, and maximize their profits. Such algorithm also provides a reference model for the practical application.%采用两级动态频谱接入网络模型,提出了基于市场竞争的三阶段动态博弈频谱接入算法.利用逆推法和Bertrand博弈理论解决动态频谱接入问题.两个寡头(移动虚拟运营商:MVNO)先后确定所需频谱数并进行价格竞争吸引终端次用户,次用户可根据对速率和价格的不同偏好进行选择.理论推导和仿真分析了算法的正确性和稳定性,证明该算法存在唯一纳什均衡.仿真结果表明,MVNOs可以灵活做出最优投资和价格决定,达到收益最大化,为实际应用提供了参考模型.

  16. Competition with Dynamic Spectrum Leasing

    CERN Document Server

    Duan, Lingjie; Shou, Biying

    2010-01-01

    This paper presents a comprehensive analytical study of two competitive cognitive operators' spectrum leasing and pricing strategies, taking into account operators' heterogeneity in leasing costs and users' heterogeneity in transmission power and channel conditions. We model the interactions between operators and users as a three-stage dynamic game, where operators make simultaneous spectrum leasing and pricing decisions in Stages I and II, and users make purchase decisions in Stage III. Using backward induction, we are able to completely characterize the game's equilibria. We show that both operators make the equilibrium leasing and pricing decisions based on simple threshold policies. Moreover, two operators always choose the same equilibrium price despite their difference in leasing costs. Each user receives the same signal-to-noise-ratio (SNR) at the equilibrium, and the obtained payoff is linear in its transmission power and channel gain. We also compare the duopoly equilibrium with the coordinated case ...

  17. 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...

  18. Spectrum access games for cognitive radio networks

    CSIR Research Space (South Africa)

    Masonta, MT

    2010-09-01

    Full Text Available Cognitive Radio (CR) is seen as a key enabling technology for addressing current under-utilization and inefficient use of radio frequency spectrum. The use of CR will see most of the spectrum white spaces being used opportunistically without causing...

  19. Dynamic Spectrum Management for Military Wireless Networks

    Science.gov (United States)

    2010-09-01

    information society . The term “dynamic spectrum management” (DSM) covers a range of different subjects areas like dynamic channel allocation (DCA...the potential for the military to share spectrum spatially and temporally with multiple devices, 2003 (European Union) Information Society Technologies...E2ER) Project initiated in Information Society Technologies, 2005 (United States): DARPA XG and NSF projects complete a series of spectrum occupancy

  20. Flexible access control for dynamic collaborative environments

    NARCIS (Netherlands)

    Dekker, Mari Antonius Cornelis

    2009-01-01

    Access control is used in computer systems to control access to confidential data. In this thesis we focus on access control for dynamic collaborative environments where multiple users and systems access and exchange data in an ad hoc manner. In such environments it is difficult to protect confident

  1. Spectrum access and management for cognitive radio networks

    CERN Document Server

    2017-01-01

    This book presents cutting-edge research contributions that address various aspects of network design, optimization, implementation, and application of cognitive radio technologies. It demonstrates how to make better utilization of the available spectrum, cognitive radios and spectrum access to achieve effective spectrum sharing between licensed and unlicensed users. The book provides academics and researchers essential information on current developments and future trends in cognitive radios for possible integration with the upcoming 5G networks. In addition, it includes a brief introduction to cognitive radio networks for newcomers to the field.

  2. Dynamic spectrum management: an impact on EW systems

    Science.gov (United States)

    Gajewski, P.; Łopatka, J.; Suchanski, M.

    2017-04-01

    Rapid evolution of wireless systems caused an enormous growth of data streams transmitted through the networks and, as a consequence, an accompanying demand concerning spectrum resources (SR). An avoidance of advisable disturbances is one of the main demands in military communications. To solve the interference problems, dynamic spectrum management (DSM) techniques can be used. Two main techniques are possible: centralized Coordinated Dynamic Spectrum Access (CDSA) and distributed Opportunistic Spectrum Access (OSA). CDSA enables the wireless networks planning automation, and systems dynamic reaction to random changes of Radio Environment (RE). For OSA, cognitive radio (CR) is the most promising technology that enables avoidance of interference with the other spectrum users due to CR's transmission parameters adaptation to the current radio situation, according to predefined Radio Policies rules. If DSM techniques are used, the inherent changes in EW systems are also needed. On one hand, new techniques of jamming should be elaborated, on the other hand, the rules and protocols of cooperation between communication network and EW systems should be developed.

  3. Dynamic Spectrum Detection Via Compressive Sensing

    Directory of Open Access Journals (Sweden)

    Michael Odeyomi

    2012-04-01

    Full Text Available Spectrum congestion is a major concern in both military and commercial wireless networks. To support growing demand for ubiquitous spectrum usage, Cognitive Radio is a new paradigm in wireless communication that can be used to exploit unused part of the spectrum by dynamically adjusting its operating parameters. While cognitive radio technology is a promising solution to the spectral congestion problem, efficient methods for detecting white spaces in wideband radio spectrum remain a challenge. Conventional methods of detection are forced to use the high sampling rate requirement of Nyquist criterion. In this paper, the feasibility and efficacy of using compressive sensing (CS algorithms inconjunction with Haar wavelet for identifying spectrum holes in the wideband spectrum is explored. Compressive sensing is an emerging theory that shows that it’s possible to achieve good reconstruction, at sampling rates lower than that specified by Nyquist. CS approach is robust in AWGN and fading channel.

  4. Baryon spectrum and chiral dynamics

    CERN Document Server

    Glozman, L Ya

    1995-01-01

    New results on baryon structure and spectrum developed in collaboration with Dan Riska [1-4] are reported. The main idea is that beyond the chiral symmetry spontaneous breaking scale light and strange baryons should be considered as systems of three constituent quarks with an effective confining interaction and a chiral interaction that is mediated by the octet of Goldstone bosons (pseudoscalar mesons) between the constituent quarks.

  5. Throughput optimization for dual collaborative spectrum sensing with dynamic scheduling

    Science.gov (United States)

    Cui, Cuimei; Yang, Dezhi

    2017-07-01

    Cognitive radio technology is envisaged to alleviate both spectrum inefficiency and spectrum scarcity problems by exploiting the existing licensed spectrum opportunistically. However, cognitive radio ad hoc networks (CRAHNs) impose unique challenges due to the high dynamic scheduling in the available spectrum, diverse quality of service (QOS) requirements, as well as hidden terminals and shadow fading issues in a harsh radio environment. To solve these problems, this paper proposes a dynamic and variable time-division multiple-access scheduling mechanism (DV-TDMA) incorporated with dual collaborative spectrum sensing scheme for CRAHNs. This study involves the cross-layered cooperation between the Physical (PHY) layer and Medium Access Control (MAC) layer under the consideration of average sensing time, sensing accuracy and the average throughput of cognitive radio users (CRs). Moreover, multiple-objective optimization algorithm is proposed to maximize the average throughput of CRs while still meeting QOS requirements on sensing time and detection error. Finally, performance evaluation is conducted through simulations, and the simulation results reveal that this optimization algorithm can significantly improve throughput and sensing accuracy and reduce average sensing time.

  6. 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.

  7. String Analysis for Dynamic Field Access

    DEFF Research Database (Denmark)

    Madsen, Magnus; Andreasen, Esben

    2014-01-01

    In JavaScript, and scripting languages in general, dynamic field access is a commonly used feature. Unfortunately, current static analysis tools either completely ignore dynamic field access or use overly conservative approximations that lead to poor precision and scalability. We present new string...... domains to reason about dynamic field access in a static analysis tool. A key feature of the domains is that the equal, concatenate and join operations take Ο(1) time. Experimental evaluation on four common JavaScript libraries, including jQuery and Prototype, shows that traditional string domains...

  8. Research and Implementation of Carrier Aggregation Technology based on Dynamic Spectrum Access%基于动态频谱接入的载波聚合技术研究与实现

    Institute of Scientific and Technical Information of China (English)

    周娟; 葛万成; 汪亮友; 林佳燕

    2015-01-01

    以LTE-Advanced系统为研究背景,提出了一种基于动态频谱接入技术的载波聚合方案( DSA-CA)。该方案的主要思想是使支持载波聚合技术的eNB根据小区的平均负载自适应地调节聚合的载波数量,从而达到合理利用频谱的目的。通过对基于动态频谱接入技术的载波聚合方案在LTE-Advanced 系统中的性能进行仿真研究,结果表明:DSA-CA方案与传统载波聚合方案( CA)相比,可使系统性能在一定程度上得到提高,尤其当一个小区处于高负载、另一个小区处于低负载时, DSA-CA方案的优势更加明显,此时高负载小区系统吞吐量得到明显提高,低负载小区的频谱效率也显著上升。%With LTE-Advanced system as the research background, a DSA-CA ( Carrier Aggregation based on Dynamic Spectrum Access) scheme is proposed. The main idea of this scheme is to adaptively adjust polymerized carriers amount in accordance with the average load of the cells at eNB in support of carrier aggregation technology, thus to achieve rational utilization of spectrum. The performance of carrier aggregation scheme based on DSA-CA in LTE-Advanced system is simulated and researched, and the ex-periment result indicates that compared with traditional CA scheme, DSA-CA improves system perform-ance to a certain degree. Especially on the condition that one cell is at high loads and the other at low loads, DSA-CA scheme enjoys more obvious superiority, and the throughput of the high-loaded cell is ob-viously enhanced, while spectral efficiency of the low-loaded cell significantly raised.

  9. Intelligent Caching Wireless Data Access in the Wireless Spectrum

    Directory of Open Access Journals (Sweden)

    Syazwa Mad Jais

    2013-05-01

    Full Text Available The evolution wireless technologies are growing rapidly in upcoming years. It is expected that many users will shift to more advanced devices that will contribute to gain higher demand in wireless spectrum. However, the capacity for the allocation frequency in the wireless spectrum is typically limited in wireless data transmission. Therefore, when the loads of wireless users in the wireless communications are increasing, the need of cache mechanisms such as Web caches or Web servers are crucial. The scalability demands on internet infrastructure keep increasing as the internet continues to grow in popularity and size. Therefore, the existence and development in Web caching technologies will contribute to bandwidth savings, network latency reduction, improve content availability and subsequently server load balancing. This paper will studies and investigates the cache performance in wireless spectrum with the purpose of dealing with the data growth since the spectrum crisis becomes a serious matter lately. The performance improvement will be observed using caching scheme which allows for time shifting and load shifting in accessing the wireless data with the better cache deployment in the network system.

  10. 认知MIMO无线网络中的多买家动态频谱接入技术%Dynamic spectrum access for multi-type buyers in cognitive MIMO radio networks

    Institute of Scientific and Technical Information of China (English)

    钟卫; 徐友云; 陈晶晶; 黄龙; 张旺

    2014-01-01

    A game theoretic framework of the auction based dynamic spectrum access for multi-type buyers ( i. e. , the secondary users that have different risk preferences) in cognitive MIMO networks was presented in this paper where the auction mechanisms of the primary user are parameterized and can be adaptively designed. The proposed game is a discrete game which must have at least one mixed or pure strategy Nash equilibrium. Based on the con-cept of learning automata, a distributed algorithm was proposed to learn the Nash equilibrium of the proposed game with limited feedback. Simulation results show that our proposed algorithm is efficient and can achieve much higher performance than the traditional fixed auction mechanism schemes and the random algorithm.%研究了认知MIMO无线网络中基于博弈论的动态频谱接入技术,以使得具有不同风险偏好的次级用户(买家)可以动态地选择竞标策略,同时主用户也可以根据系统情况,自适应地调整拍卖机制。基于非合作博弈设计了一个有限离散博弈模型,该博弈至少有一个混合策略的纳什均衡。基于自动学习机的概念,设计了一个有限反馈的分布式随机学习算法。仿真结果表明,所设计的算法具有良好的性能,与传统的固定竞拍机制和随机的选择竞价策略相比,该算法能够帮助主用户获得更高的利润,且让次级用户根据自身的风险偏好,选择一个合理的竞拍策略。

  11. The dynamic histopathologic spectrum of lung cancer.

    Science.gov (United States)

    Yesner, R

    1981-01-01

    The APUD concept has postulated that pulmonary carcinoids and small cell carcinomas arise from the neural crest. In development from hypothesis to tautology is traced, and evidence is presented that all pulmonary epithelial tumors arise from the primitive endoderm. Morphologic studies show that a dynamic spectrum exists. Not only do various cell types appear within a single section, but cell types may change from biopsy to autopsy with or without chemotherapy. The spectrum is sustained at the ultramicroscopic level in regard to organelles such as desmosomes, tonofibrils, and dense core granules. Secretory products such as ACTH and L-dopa decarboxylase also show that all lung cancers are related. Epidemiologic evidence indicates that small cell carcinomas in uranium miners occur after prolonged squamous cell dysplasia, and that carcinoids occur independently of external carcinogens, but show transitions to other tumors. Finally, experimental evidence indicates that the K cells, to which carcinoids are most closely related, are of local origin.

  12. 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.

  13. Resource allocation in shared spectrum access communications for operators with diverse service requirements

    Science.gov (United States)

    Kibria, Mirza Golam; Villardi, Gabriel Porto; Ishizu, Kentaro; Kojima, Fumihide; Yano, Hiroyuki

    2016-12-01

    In this paper, we study inter-operator spectrum sharing and intra-operator resource allocation in shared spectrum access communication systems and propose efficient dynamic solutions to address both inter-operator and intra-operator resource allocation optimization problems. For inter-operator spectrum sharing, we present two competent approaches, namely the subcarrier gain-based sharing and fragmentation-based sharing, which carry out fair and flexible allocation of the available shareable spectrum among the operators subject to certain well-defined sharing rules, traffic demands, and channel propagation characteristics. The subcarrier gain-based spectrum sharing scheme has been found to be more efficient in terms of achieved throughput. However, the fragmentation-based sharing is more attractive in terms of computational complexity. For intra-operator resource allocation, we consider resource allocation problem with users' dissimilar service requirements, where the operator supports users with delay constraint and non-delay constraint service requirements, simultaneously. This optimization problem is a mixed-integer non-linear programming problem and non-convex, which is computationally very expensive, and the complexity grows exponentially with the number of integer variables. We propose less-complex and efficient suboptimal solution based on formulating exact linearization, linear approximation, and convexification techniques for the non-linear and/or non-convex objective functions and constraints. Extensive simulation performance analysis has been carried out that validates the efficiency of the proposed solution.

  14. Dynamic Spectrum Leasing to Cooperating Secondary Networks

    CERN Document Server

    Li, Cuilian

    2008-01-01

    We propose and analyze a dynamic implementation of the property-rights model of cognitive radio, whereby a primary link has the possibility to lease the owned spectrum to a MAC network of secondary nodes in exchange for cooperation in the form of distributed space-time coding. On one hand, the primary link attempts to maximize its quality of service in terms of Signal-to-interference-plus-noise ratio (SINR), accounting for the possible contribution from cooperation. On the other hand, nodes in the secondary network compete among themselves for transmission within the leased time-slot following a distributed heterogeneous opportunistic power control mechanism. The cooperation and competition between the primary and secondary network are cast in the framework of sequential game. We give consider both a baseline model with complete information and a more practical version with incomplete information, Using the backward induction approach for the former and providing approximating algorithm for the latter. Analys...

  15. Baryon Spectrum Analysis using Covariant Constraint Dynamics

    Science.gov (United States)

    Whitney, Joshua; Crater, Horace

    2012-03-01

    The energy spectrum of the baryons is determined by treating each of them as a three-body system with the interacting forces coming from a set of two-body potentials that depend on both the distance between the quarks and the spin and orbital angular momentum coupling terms. The Two Body Dirac equations of constraint dynamics derived by Crater and Van Alstine, matched with the quasipotential formalism of Todorov as the underlying two-body formalism are used, as well as the three-body constraint formalism of Sazdjian to integrate the three two-body equations into a single relativistically covariant three body equation for the bound state energies. The results are analyzed and compared to experiment using a best fit method and several different algorithms, including a gradient approach, and Monte Carlo method. Results for all well-known baryons are presented and compared to experiment, with good accuracy.

  16. Cross-Layer Design in Dynamic Spectrum Sharing Systems

    Directory of Open Access Journals (Sweden)

    Shadmand A

    2010-01-01

    Full Text Available We consider a dynamic spectrum sharing system consisting of a primary user, whose licensed spectrum is allowed to be accessed by a secondary user as long as it does not violate the prescribed interference limit inflicted on the primary user. Assuming the Nakagami- block-fading environment, we aim at maximizing the performance of secondary user's link in terms of average spectral efficiency (ASE and error performance under the specified packet error rate (PER and average interference limit constraints. To this end, we employ a cross-layer design policy which combines adaptive power and coded discrete M-QAM modulation scheme at the physical layer with a truncated automatic repeat request (ARQ protocol at the data link layer, and simultaneously satisfies the aforementioned constraints. Numerical results affirm that the secondary link of spectrum sharing system combining ARQ with adaptive modulation and coding (AMC achieves significant gain in ASE depending on the maximum number of retransmissions initiated by the ARQ protocol. The results further indicate that the ARQ protocol essentially improves the packet loss rate performance of the secondary link.

  17. Dynamic Resource Allocation in Hybrid Access Femtocell Network

    Directory of Open Access Journals (Sweden)

    Afaz Uddin Ahmed

    2014-01-01

    Full Text Available Intercell interference is one of the most challenging issues in femtocell deployment under the coverage of existing macrocell. Allocation of resources between femtocell and macrocell is essential to counter the effects of interference in dense femtocell networks. Advances in resource management strategies have improved the control mechanism for interference reduction at lower node density, but most of them are ineffective at higher node density. In this paper, a dynamic resource allocation management algorithm (DRAMA for spectrum shared hybrid access OFDMA femtocell network is proposed. To reduce the macro-femto-tier interference and to improve the quality of service, the proposed algorithm features a dynamic resource allocation scheme by controlling them both centrally and locally. The proposed scheme focuses on Femtocell Access Point (FAP owners’ satisfaction and allows maximum utilization of available resources based on congestion in the network. A simulation environment is developed to study the quantitative performance of DRAMA in hybrid access-control femtocell network and compare it to closed and open access mechanisms. The performance analysis shows that higher number of random users gets connected to the FAP without compromising FAP owners’ satisfaction allowing the macrocell to offload a large number of users in a dense heterogeneous network.

  18. Cognitive Spectrum Efficient Multiple Access Technique using Relay Systems

    DEFF Research Database (Denmark)

    Frederiksen, Flemming Bjerge; Prasad, Ramjee

    2007-01-01

    Methods to enhance the use of the frequency spectrum by automatical spectrum sensing plus spectrum sharing in a cognitive radio technology context will be presented and discussed in this paper. Ideas to increase the coverage of cellular systems by relay channels, relay stations and collaborate ra...

  19. Cognitive Spectrum Efficient Multiple Access Technique using Relay Systems

    DEFF Research Database (Denmark)

    Frederiksen, Flemming Bjerge; Prasad, Ramjee

    2007-01-01

    Methods to enhance the use of the frequency spectrum by automatical spectrum sensing plus spectrum sharing in a cognitive radio technology context will be presented and discussed in this paper. Ideas to increase the coverage of cellular systems by relay channels, relay stations and collaborate...

  20. 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.

  1. Multiagent -Learning for Aloha-Like Spectrum Access in Cognitive Radio Systems

    Directory of Open Access Journals (Sweden)

    Li Husheng

    2010-01-01

    Full Text Available An Aloha-like spectrum access scheme without negotiation is considered for multiuser and multichannel cognitive radio systems. To avoid collisions incurred by the lack of coordination, each secondary user learns how to select channels according to its experience. Multiagent reinforcement leaning (MARL is applied for the secondary users to learn good strategies of channel selection. Specifically, the framework of -learning is extended from single user case to multiagent case by considering other secondary users as a part of the environment. The dynamics of the -learning are illustrated using a Metrick-Polak plot, which shows the traces of -values in the two-user case. For both complete and partial observation cases, rigorous proofs of the convergence of multiagent -learning without communications, under certain conditions, are provided using the Robins-Monro algorithm and contraction mapping, respectively. The learning performance (speed and gain in utility is evaluated by numerical simulations.

  2. Repeated Auctions with Learning for Spectrum Access in Cognitive Radio Networks

    CERN Document Server

    Han, Zhu; Poor, Vincent H

    2009-01-01

    In this paper, spectrum access in cognitive radio networks is modeled as a repeated auction game subject to monitoring and entry costs. For secondary users, sensing costs are incurred as the result of primary users' activity. Furthermore, each secondary user pays the cost of transmissions upon successful bidding for a channel. Knowledge regarding other secondary users' activity is limited due to the distributed nature of the network. The resulting formulation is thus a dynamic game with incomplete information. In this paper, an efficient bidding learning algorithm is proposed based on the outcome of past transactions. As demonstrated through extensive simulations, the proposed distributed scheme outperforms a myopic one-stage algorithm, and can achieve a good balance between efficiency and fairness.

  3. Collaboration and Coordination in Secondary Networks for Opportunistic Spectrum Access

    CERN Document Server

    Jouini, Wassim; Bononi, Luciano; Moy, Christophe

    2012-01-01

    In this paper, we address the general case of a coordinated secondary network willing to exploit communication opportunities left vacant by a licensed primary network. Since secondary users (SU) usually have no prior knowledge on the environment, they need to learn the availability of each channel through sensing techniques, which however can be prone to detection errors. We argue that cooperation among secondary users can enable efficient learning and coordination mechanisms in order to maximize the spectrum exploitation by SUs, while minimizing the impact on the primary network. To this goal, we provide three novel contributions in this paper. First, we formulate the spectrum selection in secondary networks as an instance of the Multi-Armed Bandit (MAB) problem, and we extend the analysis to the collaboration learning case, in which each SU learns the spectrum occupation, and shares this information with other SUs. We show that collaboration among SUs can mitigate the impact of sensing errors on system perf...

  4. Video Game Access, Parental Rules, and Problem Behavior: A Study of Boys with Autism Spectrum Disorder

    Science.gov (United States)

    Engelhardt, Christopher R.; Mazurek, Micah O.

    2014-01-01

    Environmental correlates of problem behavior among individuals with autism spectrum disorder remain relatively understudied. The current study examined the contribution of in-room (i.e. bedroom) access to a video game console as one potential correlate of problem behavior among a sample of 169 boys with autism spectrum disorder (ranging from 8 to…

  5. Framework for TV white space spectrum access in Southern African Development Community (SADC)

    CSIR Research Space (South Africa)

    Masonta, MT

    2013-09-01

    Full Text Available The global migration of television (TV) from analogue to digital broadcast will see a large amount of TV spectrum available (called TV white space - TVWS) for other services such as mobile and broadband wireless access (BWA). Leading spectrum...

  6. Coalitional Games in Partition Form for Joint Spectrum Sensing and Access in Cognitive Radio Networks

    CERN Document Server

    Saad, Walid; Zheng, Rong; Hjørungnes, Are; Başar, Tamer; Poor, H Vincent

    2012-01-01

    Unlicensed secondary users (SUs) in cognitive radio networks are subject to an inherent tradeoff between spectrum sensing and spectrum access. Although each SU has an incentive to sense the primary user (PU) channels for locating spectrum holes, this exploration of the spectrum can come at the expense of a shorter transmission time, and, hence, a possibly smaller capacity for data transmission. This paper investigates the impact of this tradeoff on the cooperative strategies of a network of SUs that seek to cooperate in order to improve their view of the spectrum (sensing), reduce the possibility of interference among each other, and improve their transmission capacity (access). The problem is modeled as a coalitional game in partition form and an algorithm for coalition formation is proposed. Using the proposed algorithm, the SUs can make individual distributed decisions to join or leave a coalition while maximizing their utilities which capture the average time spent for sensing as well as the capacity achi...

  7. Coalitional Games in Partition Form for Joint Spectrum Sensing and Access in Cognitive Radio Networks

    Science.gov (United States)

    Saad, Walid; Han, Zhu; Zheng, Rong; Hjorungnes, Are; Basar, Tamer; Poor, H. Vincent

    2012-04-01

    Unlicensed secondary users (SUs) in cognitive radio networks are subject to an inherent tradeoff between spectrum sensing and spectrum access. Although each SU has an incentive to sense the primary user (PU) channels for locating spectrum holes, this exploration of the spectrum can come at the expense of a shorter transmission time, and, hence, a possibly smaller capacity for data transmission. This paper investigates the impact of this tradeoff on the cooperative strategies of a network of SUs that seek to cooperate in order to improve their view of the spectrum (sensing), reduce the possibility of interference among each other, and improve their transmission capacity (access). The problem is modeled as a coalitional game in partition form and an algorithm for coalition formation is proposed. Using the proposed algorithm, the SUs can make individual distributed decisions to join or leave a coalition while maximizing their utilities which capture the average time spent for sensing as well as the capacity achieved while accessing the spectrum. It is shown that, by using the proposed algorithm, the SUs can self-organize into a network partition composed of disjoint coalitions, with the members of each coalition cooperating to jointly optimize their sensing and access performance. Simulation results show the performance improvement that the proposed algorithm yields with respect to the non-cooperative case. The results also show how the algorithm allows the SUs to self-adapt to changes in the environment such as the change in the traffic of the PUs, or slow mobility.

  8. Research on Performance of Dynamic Spectrum Access Based on Network Coding%基于网络编码的动态频谱接入性能研究

    Institute of Scientific and Technical Information of China (English)

    王助娟; 张轶

    2016-01-01

    The feasibility of the application of network coding to cognitive radio network was discussed in this paper. The user service performance of network coding in wireless network was analyzed by means of Markov model. Theoretical analysis and numerical simulation show that network coding can effectively reduce the conflict probability of secondary and primary users, increase user throughput. In addition, its application to spectrum allocation is able to improve the spectrum prediction capability of the primary users and beneficial for the spectrum utilization of primary and secondary users.%探讨了网络编码应用到认知无线电网络中的可能性,通过马尔可夫模型分析了采用网络编码技术后无线网络中的用户服务性能,并通过理论分析和数值仿真表验证了网络编码技术可有效降低次用户和主用户的冲突概率,增加次用户的实际吞吐率;同时应用在频谱分配机制中也可改进主用户的频谱预测能力,对主、次用户频谱的利用均有所帮助。

  9. Extended Virtual Boundary and Its Application in Dynamic Spectrum Allocation

    Institute of Scientific and Technical Information of China (English)

    Muhammad Qadeer Sharif; Pingzhi Fan

    2007-01-01

    This paper presents an efficient dynamic spectrum allocation (DSA) scheme in a flexible spectrum licensing environment where multiple networks coexist and interfere with each other. In particular, an extension of virtual boundary concept in DSA is proposed, which is spectrally efficient than the previous virtual boundary concept applied to donor systems only. Here, the same technique is applied to both donor and rental systems so as to further reduce the occurrences where the insertion of guard bands is obligatory and as a result provides better spectral efficiency. The proposed extension improves the spectrum utilization without any compromise on interference and fairness issues.

  10. Optimal Spectrum Access for Users in Multi-Channel Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Vivek Agrawal

    2013-09-01

    Full Text Available Cognitive Radio, a software defined radio, is an emerging technology which uses opportunistic spectrum access (OSA for the efficient utilization of the spectrum. Its main aim is to utilize the unused portions of the spectrum by allowing unlicensed users (secondary users to transmit data in absence of primary users. In this paper the assignment of multiple primary and secondary users in a multiple channel system is addressed with the sole aim of optimizing the total throughput. We have considered an optimal spectrum access (OSA algorithm for the allotment of both the primary and secondary users in a multiple channel system and compared the results with the well-known meta-heuristic techniques such as Simulated Annealing (SA and Tabu Search (TS. The results reveal that OSA algorithm is more efficient as compared to SA and TS as far as throughput optimization is considered.

  11. Proof-of-Concept System for Opportunistic Spectrum Access in Multi-user Decentralized Networks

    Directory of Open Access Journals (Sweden)

    Sumit J. Darak

    2016-09-01

    Full Text Available Poor utilization of an electromagnetic spectrum and ever increasing demand for spectrum have led to surge of interests in opportunistic spectrum access (OSA based paradigms like cognitive radio and unlicensed LTE. In OSA for decentralized networks, frequency band selection from wideband spectrum is a challenging task since secondary users (SUs do not share any information with each other. In this paper, a new decision making policy (DMP has been proposed for OSA in the multi-user decentralized networks. First contribution is an accurate characterization of frequency bands using Bayes-UCB algorithm. Then, a novel SU orthogonization scheme using Bayes-UCB algorithm is proposed replacing randomization based scheme. At the end, USRP testbed has been developed for analyzing the performance of DMPs using real radio signals. Experimental results show that the proposed DMP offers significant improvement in spectrum utilization, fewer subband switching and collisions compared to other DMPs.

  12. Ultrasonic Multiple-Access Ranging System Using Spread Spectrum and MEMS Technology for Indoor Localization

    Directory of Open Access Journals (Sweden)

    Laurent Segers

    2014-02-01

    Full Text Available Indoor localization of persons and objects poses a great engineering challenge. Previously developed localization systems demonstrate the use of wideband techniques in ultrasound ranging systems. Direct sequence and frequency hopping spread spectrum ultrasound signals have been proven to achieve a high level of accuracy. A novel ranging method using the frequency hopping spread spectrum with finite impulse response filtering will be investigated and compared against the direct sequence spread spectrum. In the first setup, distances are estimated in a single-access environment, while in the second setup, two senders and one receiver are used. During the experiments, the micro-electromechanical systems are used as ultrasonic sensors, while the senders were implemented using field programmable gate arrays. Results show that in a single-access environment, the direct sequence spread spectrum method offers slightly better accuracy and precision performance compared to the frequency hopping spread spectrum. When two senders are used, measurements point out that the frequency hopping spread spectrum is more robust to near-far effects than the direct sequence spread spectrum.

  13. Video game access, parental rules, and problem behavior: a study of boys with autism spectrum disorder.

    Science.gov (United States)

    Engelhardt, Christopher R; Mazurek, Micah O

    2014-07-01

    Environmental correlates of problem behavior among individuals with autism spectrum disorder remain relatively understudied. The current study examined the contribution of in-room (i.e. bedroom) access to a video game console as one potential correlate of problem behavior among a sample of 169 boys with autism spectrum disorder (ranging from 8 to 18 years of age). Parents of these children reported on (1) whether they had specific rules regulating their child's video game use, (2) whether their child had in-room access to a variety of screen-based media devices (television, computer, and video game console), and (3) their child's oppositional behaviors. Multivariate regression models showed that in-room access to a video game console predicted oppositional behavior while controlling for in-room access to other media devices (computer and television) and relevant variables (e.g. average number of video game hours played per day). Additionally, the association between in-room access to a video game console and oppositional behavior was particularly large when parents reported no rules on their child's video game use. The current findings indicate that both access and parental rules regarding video games warrant future experimental and longitudinal research as they relate to problem behavior in boys with autism spectrum disorder.

  14. Entanglement spectrum in cluster dynamical mean-field theory

    Science.gov (United States)

    Udagawa, Masafumi; Motome, Yukitoshi

    2015-01-01

    We study the entanglement spectrum of the Hubbard model at half filling on a kagome lattice. The entanglement spectrum is defined by the set of eigenvalues of a reduced thermal density matrix, which is naturally obtained in the framework of the dynamical mean-field theory. Adopting the cluster dynamical mean-field theory combined with continuous-time auxiliary-field Monte Carlo method, we calculate the entanglement spectrum for a three-site triangular cluster in the kagome Hubbard model. We find that the results at the three-particle sector well capture the qualitative nature of the system. In particular, the eigenvalue of the reduced density matrix, corresponding to the chiral degrees of freedom, exhibits a characteristic temperature scale Tchiral, below which a metallic state with large quasiparticle mass is stabilized. The entanglement spectra at different particle number sectors also exhibit characteristic changes around Tchiral, implying the development of inter-triangular ferromagnetic correlations in the correlated metallic regime.

  15. On the Feasibility of Low-Power Secondary Access to 960-1215 MHz Aeronautical Spectrum

    CERN Document Server

    Obregon, Evanny; Zander, Jens

    2012-01-01

    In this paper, we analyze the feasibility of short range indoor communication using secondary spectrum access to the 960-1215 MHz band, primarily allocated to the distance measuring equipment (DME) system for aeronautical navigation. We propose a practical secondary sharing scheme based on a combination of geo-location databases and spectrum sensing. Since the DME system performs a safety-of-life function, protection from harmful interference becomes extremely critical. Secondary users estimate the propagation loss and employ an individual interference threshold to control the aggregate interference. We examine the feasibility of large scale secondary access in terms of the transmission probability (of the secondary users) that keeps the probability of harmful interference below a given limit. Delays in the database update and uncertainties in the estimated propagation losses due to fading affect the feasibility of the secondary access. We propose a cumulant-based approximation of the probability distribution...

  16. Optical-router-based dynamically reconfigurable photonic access network

    NARCIS (Netherlands)

    Roy, R.

    2014-01-01

    The Broadband photonics (BBP) project under the Freeband consortium of projects investigated the design of a dynamically reconfigurable photonic access network. Access networks form a key link in ensuring optimal bandwidth to the end user without which any improvements deeper in the network in the a

  17. Optical-router-based dynamically reconfigurable photonic access network

    NARCIS (Netherlands)

    Roy, Rajeev

    2014-01-01

    The Broadband photonics (BBP) project under the Freeband consortium of projects investigated the design of a dynamically reconfigurable photonic access network. Access networks form a key link in ensuring optimal bandwidth to the end user without which any improvements deeper in the network in the a

  18. Optical-router-based dynamically reconfigurable photonic access network

    NARCIS (Netherlands)

    Roy, R.

    2014-01-01

    The Broadband photonics (BBP) project under the Freeband consortium of projects investigated the design of a dynamically reconfigurable photonic access network. Access networks form a key link in ensuring optimal bandwidth to the end user without which any improvements deeper in the network in the

  19. 75 FR 16507 - In the Matter of Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory...

    Science.gov (United States)

    2010-04-01

    ... COMMISSION In the Matter of Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory... certain semiconductor chips having synchronous dynamic random access memory controllers and products... section 337 by importing certain semiconductor chips having synchronous dynamic random access...

  20. 75 FR 44989 - In the Matter of Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory...

    Science.gov (United States)

    2010-07-30

    ... Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory Controllers and Products... chips having synchronous dynamic random access memory controllers and product containing the same by... importing certain semiconductor chips having synchronous dynamic random access memory controllers and...

  1. Energy-Efficient Spectrum Sensing for Cognitive Radio Networks

    NARCIS (Netherlands)

    Maleki, S.

    2013-01-01

    Dynamic spectrum access employing cognitive radios has been proposed, in order to opportunistically use underutilized spectrum portions of a heavily licensed electromagnetic spectrum. Cognitive radios opportunistically share the spectrum, while avoiding any harmful interference to the primary licens

  2. Energy-Efficient Spectrum Sensing for Cognitive Radio Networks

    NARCIS (Netherlands)

    Maleki, S.

    2013-01-01

    Dynamic spectrum access employing cognitive radios has been proposed, in order to opportunistically use underutilized spectrum portions of a heavily licensed electromagnetic spectrum. Cognitive radios opportunistically share the spectrum, while avoiding any harmful interference to the primary licens

  3. Dynamic spectrum management as an anti-interference method

    Science.gov (United States)

    Suchanski, M.; Matyszkiel, R.; Kaniewski, P.; Kustra, M.; Gajewski, P.; Łopatka, J.

    2017-04-01

    The rapid development of systems which use wireless technologies causes the escalation of the spectrum shortage problem. That is why the concept of coordinated dynamic spectrum management has appeared. It improves efficiency of the spectrum use and makes radio communication systems more resistant to interferences. The main element of the proposed solution is a frequency broker which provides frequency assignment plans for radio networks. Direct communication between the frequency broker and radio networks enables fast change of radio data. This paper presents an anti-interference method based on dynamic spectrum management, which is an implementation and extension of IST- 104/RTG-050 research task group "Cognitive Radio in NATO II" recommendations. The solution presented by the authors was tested in emulated and real environment. The designed algorithm of frequency assignment can effectively prevent interferences (including jamming) thanks to the implementation of monitoring mechanisms capable of obtaining information about the current state of radio channels from radio networks. Directions for further development of frequency planning algorithm based on belief distorted Nash equilibria for deterministic or stochastic beliefs were proposed.

  4. Toward the excited meson spectrum of dynamical QCD

    Energy Technology Data Exchange (ETDEWEB)

    Dudek, Jozef J.; Edwards, Robert G.; Peardon, Michael J.; Richards, David G.; Thomas, Christopher E.

    2010-08-01

    We present a detailed description of the extraction of the highly excited isovector meson spectrum on dynamical anisotropic lattices using a new quark-field construction algorithm and a large variational basis of operators. With careful operator construction, the combination of these techniques is used to identify the continuum spin of extracted states reliably, overcoming the reduced rotational symmetry of the cubic lattice. Excited states, states with exotic quantum numbers (0+-, 1-+ and 2+-) and states of high spin are resolved, including, for the first time in a lattice QCD calculation, spin-four states. The determinations of the spectrum of isovector mesons and kaons are performed on dynamical lattices with two volumes and with pion masses down to ~ 400 MeV, with statistical precision typically at or below 1% even for highly excited states.

  5. Optimality of Multichannel Myopic Sensing in the Presence of Sensing Error for Opportunistic Spectrum Access

    Directory of Open Access Journals (Sweden)

    Xiaofeng Jiang

    2013-01-01

    Full Text Available The optimization problem for the performance of opportunistic spectrum access is considered in this study. A user, with the limited sensing capacity, has opportunistic access to a communication system with multiple channels. The user can only choose several channels to sense and decides whether to access these channels based on the sensing information in each time slot. Meanwhile, the presence of sensing error is considered. A reward is obtained when the user accesses a channel. The objective is to maximize the expected (discounted or average reward accrued over an infinite horizon. This problem can be formulated as a partially observable Markov decision process. This study shows the optimality of the simple and robust myopic policy which focuses on maximizing the immediate reward. The results show that the myopic policy is optimal in the case of practical interest.

  6. Highly excited and exotic meson spectrum from dynamical lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Jozef Dudek, Robert Edwards, David Richards, Christopher Thomas

    2009-12-01

    Using a new quark-field construction algorithm and a large variational basis of operators, we extract a highly excited isovector meson spectrum on dynamical anisotropic lattices. We show how carefully constructed operators can be used to identify the continuum spin of extracted states. This method allows us to extract, with confidence, excited states, states of high spin and states with exotic quantum numbers, including, for the first time, spin-four states.

  7. Local Nucleosome Dynamics Facilitate Chromatin Accessibility in Living Mammalian Cells

    Directory of Open Access Journals (Sweden)

    Saera Hihara

    2012-12-01

    Full Text Available Genome information, which is three-dimensionally organized within cells as chromatin, is searched and read by various proteins for diverse cell functions. Although how the protein factors find their targets remains unclear, the dynamic and flexible nature of chromatin is likely crucial. Using a combined approach of fluorescence correlation spectroscopy, single-nucleosome imaging, and Monte Carlo computer simulations, we demonstrate local chromatin dynamics in living mammalian cells. We show that similar to interphase chromatin, dense mitotic chromosomes also have considerable chromatin accessibility. For both interphase and mitotic chromatin, we observed local fluctuation of individual nucleosomes (∼50 nm movement/30 ms, which is caused by confined Brownian motion. Inhibition of these local dynamics by crosslinking impaired accessibility in the dense chromatin regions. Our findings show that local nucleosome dynamics drive chromatin accessibility. We propose that this local nucleosome fluctuation is the basis for scanning genome information.

  8. 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.

  9. Dynamic Spectrum Access: regulations, standards and green radio policy considerations

    CSIR Research Space (South Africa)

    Mfupe, L

    2012-09-01

    Full Text Available -related requirements of electric utilities so that FCC can advise appropriately on federal smart grid policies and governmental departments on improving the energy-efficiency of their data centres [20]. Table 1 presents a SWOT analysis on green radio policies. IV... Table 1: A summary SWOT analysis of green radio policies. Method vs. Indicator Strengths Weaknesses Opportunities Threats Green radio compliance strategies ? Some regulators, telecommunications operators and standardization bodies around...

  10. Error correction coding for frequency-hopping multiple-access spread spectrum communication systems

    Science.gov (United States)

    Healy, T. J.

    1982-01-01

    A communication system which would effect channel coding for frequency-hopped multiple-access is described. It is shown that in theory coding can increase the spectrum utilization efficiency of a system with mutual interference to 100 percent. Various coding strategies are discussed and some initial comparisons are given. Some of the problems associated with implementing the type of system described here are discussed.

  11. A Frequency—Diversity Spread—Spectrum Multiple Access System with Random Signature Sequences

    Institute of Scientific and Technical Information of China (English)

    CaoYewen; XiangHaige

    1995-01-01

    A new scheme for the spread-spectrum multiple access system named Frequency-Diver-sity Spread-Spectrum Multiple Access(FD-DDMA)system,is proposed.In this FD-SSMA sys-tem,the same information will be modulated on a group of mutually orthogonal frequency compo-nents(carriers)with a random signature sequence at the same time,and it will be demodulated by a coherent receiver for every component and then incorporated (ad if using frequency diversity)on the basis of this random sequence.The spectrum of the modulated signal is very close to that of a white-noise in a wider frequency band due to orthogonality for all frequency components and prop-erty of the random sequence,the system becomes a spread-spectrum one.The (Inverse)Fast Froier Transform(IFFT,FFT)can be applied in the system ,which provides additional flexibility.The performance in an asynchronous mode,such as ability of multiusers,anti-interferences ,is an-alyzed.

  12. A dynamic spectrum analysis solution for the characterization of the UHF spectrum

    Science.gov (United States)

    Pooler, Richard K.; Narayanan, Ram M.; Sherbondy, Kelly D.; Martone, Anthony F.; Gallagher, Kyle A.

    2016-05-01

    The Spectral Analysis Solution (SAS), under development, is a multichannel superheterodyne signal analyzer with the intended applications of radio frequency (RF) research, radar verification, and general purpose spectrum sensing, primarily in the ultra-wideband (UWB) range from ultra high frequency (UHF) to the S-band. The SAS features a wideband channel operating from 100 kHz to 1.8 GHz and eight narrowband channels having adjustable instantaneous bandwidths ranging from 1 MHz to 100 MHz. The wideband channel provides a large picture of the RF spectrum while the narrowband channels allow for high resolution, low noise floor, and high spurious free dynamic range (SFDR) capabilities. An adaptive graphic user interface (GUI) has been implemented for the system that actively pulls and processes the system data in real time. This paper outlines the motivation and theory behind the system along with system validation and implementation results.

  13. Dynamically Authorized Role-Based Access Control for Grid Applications

    Institute of Scientific and Technical Information of China (English)

    YAO Hanbing; HU Heping; LU Zhengding; LI Ruixuan

    2006-01-01

    Grid computing is concerned with the sharing and coordinated use of diverse resources in distributed "virtual organizations". The heterogeneous, dynamic and multi-domain nature of these environments makes challenging security issues that demand new technical approaches. Despite the recent advances in access control approaches applicable to Grid computing, there remain issues that impede the development of effective access control models for Grid applications. Among them there are the lack of context-based models for access control, and reliance on identity or capability-based access control schemes. An access control scheme that resolve these issues is presented, and a dynamically authorized role-based access control (D-RBAC) model extending the RBAC with context constraints is proposed. The D-RABC mechanisms dynamically grant permissions to users based on a set of contextual information collected from the system and user's environments, while retaining the advantages of RBAC model. The implementation architecture of D-RBAC for the Grid application is also described.

  14. PERFORMANCE OF OPPORTUNISTIC SPECTRUM ACCESS WITH SENSING ERROR IN COGNITIVE RADIO AD HOC NETWORKS

    Directory of Open Access Journals (Sweden)

    N. ARMI

    2012-04-01

    Full Text Available Sensing in opportunistic spectrum access (OSA has a responsibility to detect the available channel by performing binary hypothesis as busy or idle states. If channel is busy, secondary user (SU cannot access and refrain from data transmission. SU is allowed to access when primary user (PU does not use it (idle states. However, channel is sensed on imperfect communication link. Fading, noise and any obstacles existed can cause sensing errors in PU signal detection. False alarm detects idle states as a busy channel while miss-identification detects busy states as an idle channel. False detection makes SU refrain from transmission and reduces number of bits transmitted. On the other hand, miss-identification causes SU collide to PU transmission. This paper study the performance of OSA based on the greedy approach with sensing errors by the restriction of maximum collision probability allowed (collision threshold by PU network. The throughput of SU and spectrum capacity metric is used to evaluate OSA performance and make comparisons to those ones without sensing error as function of number of slot based on the greedy approach. The relations between throughput and signal to noise ratio (SNR with different collision probability as well as false detection with different SNR are presented. According to the obtained results show that CR users can gain the reward from the previous slot for both of with and without sensing errors. It is indicated by the throughput improvement as slot number increases. However, sensing on imperfect channel with sensing errors can degrade the throughput performance. Subsequently, the throughput of SU and spectrum capacity improves by increasing maximum collision probability allowed by PU network as well. Due to frequent collision with PU, the throughput of SU and spectrum capacity decreases at certain value of collision threshold. Computer simulation is used to evaluate and validate these works.

  15. The Dynamics of Access to Groups in Working Memory

    Science.gov (United States)

    Farrell, Simon; Lelievre, Anna

    2012-01-01

    The finding that participants leave a pause between groups when attempting serial recall of temporally grouped lists has been taken to indicate access to a hierarchical representation of the list in working memory. An alternative explanation is that the dynamics of serial recall solely reflect output (rather than memorial) processes, with the…

  16. Dirac's Covariant Constraint Dynamics Applied to the Baryon Spectrum

    Science.gov (United States)

    Whitney, Joshua; Crater, Horace

    2010-02-01

    A baryon is a hadron containing three quarks in a combination of up, down, strange, charm, or bottom. For prediction of the baryon energy spectrum, a baryon is modeled as a three-body system with the interacting forces coming from a set of two-body potentials that depend on the distance between the quarks, the spin-spin and spin-orbit angular momentum coupling terms, and a tensor term. Techniques and equations are derived from Todorov's work on constraint dynamics and the quasi-potential equation together with Two Body Dirac equations developed by Crater and Van Alstine, and adapted to this specific problem by further use of Sazdjian's N-body constraints dynamics for general confined systems. Baryon spectroscopy results are presented and compared with experiment. Typically, a best fit method is used in the analyses that employ several different algorithms, including a gradient approach, Monte Carlo modeling, and simulated annealing methods. )

  17. Dynamic fair node spectrum allocation for ad hoc networks using random matrices

    Science.gov (United States)

    Rahmes, Mark; Lemieux, George; Chester, Dave; Sonnenberg, Jerry

    2015-05-01

    Dynamic Spectrum Access (DSA) is widely seen as a solution to the problem of limited spectrum, because of its ability to adapt the operating frequency of a radio. Mobile Ad Hoc Networks (MANETs) can extend high-capacity mobile communications over large areas where fixed and tethered-mobile systems are not available. In one use case with high potential impact, cognitive radio employs spectrum sensing to facilitate the identification of allocated frequencies not currently accessed by their primary users. Primary users own the rights to radiate at a specific frequency and geographic location, while secondary users opportunistically attempt to radiate at a specific frequency when the primary user is not using it. We populate a spatial radio environment map (REM) database with known information that can be leveraged in an ad hoc network to facilitate fair path use of the DSA-discovered links. Utilization of high-resolution geospatial data layers in RF propagation analysis is directly applicable. Random matrix theory (RMT) is useful in simulating network layer usage in nodes by a Wishart adjacency matrix. We use the Dijkstra algorithm for discovering ad hoc network node connection patterns. We present a method for analysts to dynamically allocate node-node path and link resources using fair division. User allocation of limited resources as a function of time must be dynamic and based on system fairness policies. The context of fair means that first available request for an asset is not envied as long as it is not yet allocated or tasked in order to prevent cycling of the system. This solution may also save money by offering a Pareto efficient repeatable process. We use a water fill queue algorithm to include Shapley value marginal contributions for allocation.

  18. Spectrum sharing in cognitive radio networks medium access control protocol based approach

    CERN Document Server

    Pandit, Shweta

    2017-01-01

    This book discusses the use of the spectrum sharing techniques in cognitive radio technology, in order to address the problem of spectrum scarcity for future wireless communications. The authors describe a cognitive radio medium access control (MAC) protocol, with which throughput maximization has been achieved. The discussion also includes use of this MAC protocol for imperfect sensing scenarios and its effect on the performance of cognitive radio systems. The authors also discuss how energy efficiency has been maximized in this system, by applying a simple algorithm for optimizing the transmit power of the cognitive user. The study about the channel fading in the cognitive user and licensed user and power adaption policy in this scenario under peak transmit power and interference power constraint is also present in this book.

  19. Systematic analysis of geo-location and spectrum sensing as access methods to TV white space

    CSIR Research Space (South Africa)

    Mauwa, H

    2016-11-01

    Full Text Available -LOCATION AND SPECTRUM SENSING AS ACCESS METHODS TO TVWHITE SPACE H. Mauwa1, A. Bagula1, M. Zennaro2, E. Pietrosemoli2, A. Lysko3, T.X. Brown4 1ISAT Laboratory, Computer Science Department, University of The Western Cape (UWC), Private Bag X17, Bellville, 7535, South..., antenna parameters (radiation pat- tern, height above the ground), transmit power, times of op- eration, protection requirements, allowed WSD transmitter power, and other related parameters [6][7]. The database in- formation is used to predict which...

  20. Design and performance evaluation of a wideband FM spread-spectrum multiple-access system

    Science.gov (United States)

    Wachsman, R. H.; Ghais, A. F.

    1971-01-01

    The system described performs the tracking and communications functions of a tracking and data relay satellite system (TDRS). The spread-spectrum signal format is achieved through wide deviation FM by a sinusoidal subcarrier unique to each multiple-access user. A compound phase-locked loop tracks carrier and subcarrier and demodulates data and ranging signals. Design parameters of user and ground terminals for TDRS are given. Acquisition procedures are described. Performance analyses are presented including the effects of noise, RFI, multipath and other users.

  1. 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.

  2. Probabilistic models for access strategies to dynamic information elements

    DEFF Research Database (Denmark)

    Hansen, Martin Bøgsted; Olsen, Rasmus L.; Schwefel, Hans-Peter

    In various network services (e.g., routing and instances of context-sensitive networking) remote access to dynamically changing information elements is a required functionality. Three fundamentally different strategies for such access are investigated in this paper: (1) a reactive approach...... for information elements spread over a large number of network nodes are provided, which allow to draw conclusions on scalability properties. The impact of different distribution types for the network delays as well as for the time between changes of the information element on the mismatch probability...

  3. Secure Dynamic access control scheme of PHR in cloud computing.

    Science.gov (United States)

    Chen, Tzer-Shyong; Liu, Chia-Hui; Chen, Tzer-Long; Chen, Chin-Sheng; Bau, Jian-Guo; Lin, Tzu-Ching

    2012-12-01

    With the development of information technology and medical technology, medical information has been developed from traditional paper records into electronic medical records, which have now been widely applied. The new-style medical information exchange system "personal health records (PHR)" is gradually developed. PHR is a kind of health records maintained and recorded by individuals. An ideal personal health record could integrate personal medical information from different sources and provide complete and correct personal health and medical summary through the Internet or portable media under the requirements of security and privacy. A lot of personal health records are being utilized. The patient-centered PHR information exchange system allows the public autonomously maintain and manage personal health records. Such management is convenient for storing, accessing, and sharing personal medical records. With the emergence of Cloud computing, PHR service has been transferred to storing data into Cloud servers that the resources could be flexibly utilized and the operation cost can be reduced. Nevertheless, patients would face privacy problem when storing PHR data into Cloud. Besides, it requires a secure protection scheme to encrypt the medical records of each patient for storing PHR into Cloud server. In the encryption process, it would be a challenge to achieve accurately accessing to medical records and corresponding to flexibility and efficiency. A new PHR access control scheme under Cloud computing environments is proposed in this study. With Lagrange interpolation polynomial to establish a secure and effective PHR information access scheme, it allows to accurately access to PHR with security and is suitable for enormous multi-users. Moreover, this scheme also dynamically supports multi-users in Cloud computing environments with personal privacy and offers legal authorities to access to PHR. From security and effectiveness analyses, the proposed PHR access

  4. Dynamic Resource Access Using Graphical Game in Asymmetric Wireless Networks

    Directory of Open Access Journals (Sweden)

    Fangwei Li

    2013-08-01

    Full Text Available In order to improve the resource utilization in asymmetric wireless networks, a novel dynamic resource access algorithm was presented. As the asymmetry of information and the locality of users' actions in distributed wireless networks, the resource access problem was expressed as a simple graphical game model. Let the graphic topology indicate the internal game structure of the realistic environment. Then the Nash equilibrium was got by minimizing the individual regret instead of the system regret. The proposed algorithm realized efficient resource access through exchanging the active information and regret in the competitive community. Theoretical analysis and simulation results show that the algorithm can converge to a suitable pure strategy Nash equilibrium point quickly with less amount of calculation, avoids conflict effectively, and improves the system capacity and power utilization especially in the condition of insufficient resources

  5. Temporal Dynamics of Speech and Gesture in Autism Spectrum Disorder

    DEFF Research Database (Denmark)

    Lambrechts, Anna; Gaigg, Sebastian; Yarrow, Kielan

    2015-01-01

    Autism Spectrum Disorder (ASD) is characterized by difficulties in communication and social interaction. Abnormalities in the use of gestures or flow of conversation are frequently reported in clinical observations and contribute to a diagnosis of the disorder but the mechanisms underlying...... these communication difficulties remain unclear. In the present study, we examine the hypothesis that the temporal dynamics of speech and gesture production is atypical in ASD and affects the overall quality of communication. The context of a previously published study of memory in ASD (Maras et al., 2013) provided...... the opportunity to examine video recordings of 17 ASD and 17 TD adults attempting to recall details of a standardized event they had participated in (a first aid scenario). Results indicated no group difference in the use and coordination of speech and gesture: both groups produced the same quantity of movement...

  6. Accessing Defect Dynamics using Intense, Nanosecond Pulsed Ion Beams

    Science.gov (United States)

    Persaud, A.; Barnard, J. J.; Guo, H.; Hosemann, P.; Lidia, S.; Minor, A. M.; Seidl, P. A.; Schenkel, T.

    Gaining in-situ access to relaxation dynamics of radiation induced defects will lead to a better understanding of materials and is important for the verification of theoretical models and simulations. We show preliminary results from experiments at the new Neutralized Drift Compression Experiment (NDCX-II) at Lawrence Berkeley National Laboratory that will enable in-situ access to defect dynamics through pump-probe experiments. Here, the unique capabilities of the NDCX-II accelerator to generate intense, nanosecond pulsed ion beams are utilized. Preliminary data of channeling experiments using lithium and potassium ions and silicon membranes are shown. We compare these data to simulation results using Crystal Trim. Furthermore, we discuss the improvements to the accelerator to higher performance levels and the new diagnostics tools that are being incorporated.

  7. 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.

  8. 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.

  9. Study on the measurement method of a dynamic spectrum

    Science.gov (United States)

    Wang, Y.; Li, G.; Lin, L.; Liu, Y. L.; Li, X. X.; C-Y Lu, Stephen

    2005-01-01

    Continuous non-invasive blood component sensing and regulation is necessary for patients with metabolism disorders. Utilizing near-infrared spectroscopy for non-invasively sensing blood component concentration has been a focus topic in biomedical optics applications. It has been shown to be versatile, speedy and sensitive to several kinds of samples. However, there is no report about any successful non-invasive blood component (except the artery blood oxygen saturation) concentration detection techniques that can meet the requirements of clinic application. One of the key difficulties is the influence of individual discrepancies. Dynamic spectrum is a new non-invasive measure method for sensing blood component concentration presented recently. It can theoretically eliminate the individual discrepancies of the tissues except the pulsatile component of the artery blood. This indicates a brand new way to measure the blood component concentration and the potential to provide absolute quantitation of hemodynamic variables. In this paper, the measurement methodology to acquire the DS from photoplethysmography (PPG) is studied. A dynamic spectrometer to acquire the DS is described.

  10. Implementasi dan Evaluasi Kinerja Direct Sequence Spread Spectrum menggunakan Wireless Open-Access Research Platform (WARP

    Directory of Open Access Journals (Sweden)

    Aditya Sukmana Putra

    2015-03-01

    Full Text Available Dalam sistem komunikasi nirkabel, khususnya pada dunia komunikasi taktis atau militer, salah satu yang harus dihadapi adalah gangguan jamming.Salah satu sistem yang dapat mengatasi masalah tersebut adalah Direct Sequence Spread Spectrum (DSSS dimana informasi akan dikalikan secara langsung dengan pseudo-noise sequence yang mempunyai laju chip jauh lebih besar.Sistem ini dapat diimplementasikan pada Wireless Open-Access Research Platform (WARP yang merupakan salah satu dari jenis Software Define Radio (SDR.Modul WARP mampu diprogram secara langsung dengan software MATLAB.Kinerja sistem terbaik didapatkan ketika daya sinyal jamming lebih kecil atau sama dengan daya sinyal carrier sistem DSSS. Pada Single Tone Jamming (STJ sistem akan mencapai nilai BER 10E-3  saat daya sinyal jamming 125 % dari daya sinyal sistem DSSS, sedangkan pada Multi Tone Jamming (MTJ sistem akan mencapai BER 10E-3  saat daya sinyal jamming 100 % dari daya sistem DSSS.

  11. 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....

  12. Dynamic Behavior and Quasi-energy Spectrum of Multiband Superlattice Bloch Electrons in Quantum Kicked Potential

    Institute of Scientific and Technical Information of China (English)

    OUYANG BiYao; ZHAO XianGeng; CHEN ShiGang; LIU Jie

    2001-01-01

    In this paper, we study the dynamic behavior and quasi-energy spectrum of multiband superlattice Bloch electrons in quantum kicked potential. We show analytically and numerically the avoided crossing and band suppression about the quasi-energy spectrum, the dynamic nonlocalization, and the electron oscillation behavior between two bands.

  13. 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.

  14. On the Impact of Closed Access and Users Identities in Spectrum-Shared Overlaid Wireless Networks

    KAUST Repository

    Radaydeh, Redha M.

    2016-03-28

    © 2015 IEEE. This paper develops analytical models to investigate the impact of various operation terms and parameters on the downlink performance of spectrum-shared overlaid networks under closed-access small cells deployment. It is considered that closed-access small cells (i.e., femtocells) can not reuse available channels, and can serve only active authorized user equipments (UEs). On the other hand, the macrocell base station can unconditionally reuse available channels to serve active macrocell UEs. The analysis characterizes UEs identities, their likelihoods of being active, and their likelihoods of initiating interference. Moreover, it quantifies interference sources observed from effective femtocells considering their over-loaded and under-loaded cell scenarios. The developed results to characterize an active UE performance and the impact of the number of available channels are thoroughly examined. The obtained results are generally applicable for any performance measure and any network channel models. Numerical and simulation examples are presented to clarify the main outcomes of this paper.

  15. Dynamic Tracking of Web Activity Accessed by Users Using Cookies

    Directory of Open Access Journals (Sweden)

    K.V.S. Jaharsh Samayan

    2015-07-01

    Full Text Available The motive of this study is to suggest a protocol which can be implemented to observe the activities of any node within a network whose contribution to the organization needs to be measured. Many associates working in any organization misuse the resources allocated to them and waste their working time in unproductive work which is of no use to the organization. In order to tackle this problem the dynamic approach in monitoring web pages accessed by user using cookies gives a very efficient way of tracking all the activities of the individual and store in cookies which are generated based on their recent web activity and display a statistical information of how the users web activity for the time period has been utilized for every IP-address in the network. In a ever challenging dynamic world monitoring the productivity of the associates in the organization plays an utmost important role.

  16. Accessing Wireless Sensor Networks Via Dynamically Reconfigurable Interaction Models

    Directory of Open Access Journals (Sweden)

    Maria Cecília Gomes

    2012-12-01

    Full Text Available The Wireless Sensor Networks (WSNs technology is already perceived as fundamental for science across many domains, since it provides a low cost solution for environment monitoring. WSNs representation via the service concept and its inclusion in Web environments, e.g. through Web services, supports particularly their open/standard access and integration. Although such Web enabled WSNs simplify data access, network parameterization and aggregation, the existing interaction models and run-time adaptation mechanisms available to clients are still scarce. Nevertheless, applications increasingly demand richer and more flexible accesses besides the traditional client/server. For instance, applications may require a streaming model in order to avoid sequential data requests, or the asynchronous notification of subscribed data through the publish/subscriber. Moreover, the possibility to automatically switch between such models at runtime allows applications to define flexible context-based data acquisition. To this extent, this paper discusses the relevance of the session and pattern abstractions on the design of a middleware prototype providing richer and dynamically reconfigurable interaction models to Web enabled WSNs.

  17. 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].

  18. 75 FR 14467 - In the Matter of: Certain Dynamic Random Access Memory Semiconductors and Products Containing...

    Science.gov (United States)

    2010-03-25

    ... COMMISSION In the Matter of: Certain Dynamic Random Access Memory Semiconductors and Products Containing Same... random access memory semiconductors and products containing same, including memory modules, by reason of... after importation of certain dynamic random access memory semiconductors or products containing the...

  19. Dynamic control approaches of spectrum sensing in multi-band cognitive radio networks

    Institute of Scientific and Technical Information of China (English)

    AN Chun-yan; JI Hong; SI Peng-bo; MAO Xu

    2010-01-01

    In this paper,the dynamic control approaches for spectrum sensing are proposed,based on the theory that prediction is synonymous with data compression in computational learning. Firstly,a spectrum sensing sequence prediction scheme is proposed to reduce the spectrum sensing time and improve the throughput of secondary users. We use Ziv-Lempel data compression algorithm to design the prediction scheme,where spectrum band usage history is utilized. In addition,an iterative algorithm to find out the optimal number of spectrum bands allowed to sense is proposed,with the aim of maximizing the expected net reward of each secondary user in each time slot. Finally,extensive simulation results are shown to demonstrate the effectiveness of the proposed dynamic control approaches of spectrum sensing.

  20. Conformations of Carnosine in Aqueous Solutions by All-Atom Molecular Dynamics Simulations and 2D-NOSEY Spectrum

    Institute of Scientific and Technical Information of China (English)

    Rong Zhang; Dan Wang; Wen-juan Wu

    2013-01-01

    All-atom molecular simulations and two-dimensional nuclear overhauser effect spectrum have been used to study the conformations of carnosine in aqueous solution.Intramolecular distances,root-mean-square deviation,radius of gyration,and solvent-accessible surface are used to characterize the properties of the carnosine.Carnosine can shift between extended and folded states,but exists mostly in extended state in water.Its preference for extension in pure water has been proven by the 2D nuclear magnetic resonance (NMR) experiment.The NMR experimental results are consistent with the molecular dynamics simulations.

  1. Perception of dynamic facial emotional expressions in adolescents with autism spectrum disorders

    NARCIS (Netherlands)

    Kessels, R.P.C.; Spee, P.S.; Hendriks, A.W.C.J.

    2010-01-01

    Previous studies have shown deficits in the perception of static emotional facial expressions in individuals with autism spectrum disorders (ASD), but results are inconclusive. Possibly, using dynamic facial stimuli expressing emotions at different levels of intensities may produce more robust

  2. Perception of dynamic facial emotional expressions in adolescents with autism spectrum disorders.

    NARCIS (Netherlands)

    Kessels, R.P.C.; Spee, P.; Hendriks, A.W.

    2010-01-01

    Previous studies have shown deficits in the perception of static emotional facial expressions in individuals with autism spectrum disorders (ASD), but results are inconclusive. Possibly, using dynamic facial stimuli expressing emotions at different levels of intensities may produce more robust

  3. Lagrangian frequency spectrum as a diagnostic for magnetohydrodynamic turbulence dynamics.

    Science.gov (United States)

    Busse, Angela; Müller, Wolf-Christian; Gogoberidze, Grigol

    2010-12-01

    For the phenomenological description of magnetohydrodynamic turbulence competing models exist, e.g., Boldyrev [Phys. Rev. Lett. 96, 115002 (2006)] and Gogoberidze [Phys. Plasmas 14, 022304 (2007)], which predict the same Eulerian inertial-range scaling of the turbulent energy spectrum although they employ fundamentally different basic interaction mechanisms. A relation is found that links the Lagrangian frequency spectrum with the autocorrelation time scale of the turbulent fluctuations τ(ac) and the associated cascade time scale τ(cas). Thus, the Lagrangian energy spectrum can serve to identify weak (τ(ac) ≪ τ(cas)) and strong (τ(ac) ∼ τ(cas)) interaction mechanisms providing insight into the turbulent energy cascade. The new approach is illustrated by results from direct numerical simulations of two- and three-dimensional incompressible MHD turbulence.

  4. Switch Based Opportunistic Spectrum Access for General Primary User Traffic Model

    KAUST Repository

    Gaaloul, Fakhreddine

    2012-06-18

    This letter studies cognitive radio transceiver that can opportunistically use the available channels of primary user (PU). Specifically, we investigate 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, based on channel switching mechanism, applies when the SU has access to multiple channels but can at a given time monitor and access only one channel. For these access schemes, we derive the exact analytical results for the novel performance metrics of average access time and average waiting time under general PU traffic models.

  5. Tinamit: Making coupled system dynamics models accessible to stakeholders

    Science.gov (United States)

    Malard, Julien; Inam Baig, Azhar; Rojas Díaz, Marcela; Hassanzadeh, Elmira; Adamowski, Jan; Tuy, Héctor; Melgar-Quiñonez, Hugo

    2017-04-01

    Model coupling is increasingly used as a method of combining the best of two models when representing socio-environmental systems, though barriers to successful model adoption by stakeholders are particularly present with the use of coupled models, due to their high complexity and typically low implementation flexibility. Coupled system dynamics - physically-based modelling is a promising method to improve stakeholder participation in environmental modelling while retaining a high level of complexity for physical process representation, as the system dynamics components are readily understandable and can be built by stakeholders themselves. However, this method is not without limitations in practice, including 1) inflexible and complicated coupling methods, 2) difficult model maintenance after the end of the project, and 3) a wide variety of end-user cultures and languages. We have developed the open-source Python-language software tool Tinamit to overcome some of these limitations to the adoption of stakeholder-based coupled system dynamics - physically-based modelling. The software is unique in 1) its inclusion of both a graphical user interface (GUI) and a library of available commands (API) that allow users with little or no coding abilities to rapidly, effectively, and flexibly couple models, 2) its multilingual support for the GUI, allowing users to couple models in their preferred language (and to add new languages as necessary for their community work), and 3) its modular structure allowing for very easy model coupling and modification without the direct use of code, and to which programming-savvy users can easily add support for new types of physically-based models. We discuss how the use of Tinamit for model coupling can greatly increase the accessibility of coupled models to stakeholders, using an example of a stakeholder-built system dynamics model of soil salinity issues in Pakistan coupled with the physically-based soil salinity and water flow model

  6. WRC-07: the Technological and Market Pressures for Flexible Spectrum Access

    OpenAIRE

    Sims, Martin

    2007-01-01

    By examining the preparations for the 2007 ITU World Radio Conference (WRC-07) and associated developments this paper identifies practical examples of the market and technological pressures contributing towards a more liberalised approach to spectrum management. It argues that the need to find new spectrum for advanced mobile services (WRC-07 Agenda item 1.4), the growing orthodoxy on spectrum neutrality and the need to accommodate converging technologies are helping to undermine the stri...

  7. Spectrum Occupancy Measurements in the 2.3-2.4 GHz band: Guidelines for Licensed Shared Access in Finland

    Directory of Open Access Journals (Sweden)

    Marko Höyhtyä

    2015-05-01

    Full Text Available This paper presents results from spectrum occupancy measurements in the 2.3-2.4 GHz band at Turku, Finland. The band is currently under study in European regulation and standardization for mobile communication systems. We review the recently introduced Licensed Shared Access (LSA concept as a potential means for making the 2.3-2.4 GHz band available for mobile communications on a shared basis while protecting the rights of the incumbent spectrum users. The spectrum occupancy measurements conducted in one location in Finland show that the use of this band is rather low indicating that there might be potential for mobile communication systems to share this band with the incumbents under the LSA approach. Based on the obtained knowledge about the use of the studied band in Finland we create a set of guidelines for LSA to make the operation efficient both from the technical and economic viewpoint.

  8. Coordinated Dynamic Spectrum Management of LTE-U and Wi-Fi Networks

    OpenAIRE

    2015-01-01

    This paper investigates the co-existence of Wi-Fi and LTE in emerging unlicensed frequency bands which are intended to accommodate multiple radio access technologies. Wi-Fi and LTE are the two most prominent access technologies being deployed today, motivating further study of the inter-system interference arising in such shared spectrum scenarios as well as possible techniques for enabling improved co-existence. An analytical model for evaluating the baseline performance of co-existing Wi-Fi...

  9. Performance Evaluation of QoS Parameters in Dynamic Spectrum Sharing for Heterogeneous Wireless Communication Networks

    Directory of Open Access Journals (Sweden)

    R.Kaniezhil

    2012-01-01

    Full Text Available Cognitive radio nodes have been proposed as means to improve the spectrum utilization. It reuses the spectrum of a primary service provider under the condition that the primary service provider services are not harmfully interrupted. A cognitive radio can sense its operating environment's conditions and it is able to reconfigure itself and to communicate with other counterparts based on the status of the environment and also the requirements of the user to meet the optimal communication conditions and to keep quality of service (QoS as high as possible. The efficiency of spectrum sharing can be improved by minimizing the interference. The Utility function that captures the cooperative behavior to minimize the interference and the satisfaction to improve the throughput is investigated. The dynamic spectrum sharing algorithm can maintain the quality of service (QoS of each network while the effective spectrum utilisation is improved under a fluctuation traffic environment when the available spectrum is limited.

  10. The dynamic mechanism of presenilin-function: Sensitive gate dynamics and loop unplugging control protein access

    DEFF Research Database (Denmark)

    Somavarapu, Arun Kumar; Kepp, Kasper Planeta

    2016-01-01

    molecular dynamics in an explicit membrane with particular account of the as yet unexplored loop dynamics. We find that mature PSEN1 contains multiple distinct conformational states whereas non-mature PSEN1 is a typical one-state protein. We confirm a previously suggested gating mechanism, and find......There is no molecular explanation for the many presenilin 1 (PSEN1) mutations causing Alzheimer's disease, but both gain of function relating to amyloid production and loss of isolated PSEN1 function have been implied. We report here the first detailed dynamic all-atom model of mature PSEN1 from...... that the 106-131 loop acts as a "hinge" for the TM2 and TM6 "doors". More importantly, we identify an unplugging mechanism of the Exon 9 loop associated only with mature PSEN1. Proper opening of both the "gate" and "plug" in the membrane produces channel-like morphologies and access to the catalytic aspartates...

  11. 75 FR 55764 - Dynamic Random Access Memory Semiconductors From the Republic of Korea: Preliminary Results of...

    Science.gov (United States)

    2010-09-14

    ... International Trade Administration Dynamic Random Access Memory Semiconductors From the Republic of Korea... administrative review of the countervailing duty order on dynamic random access memory semiconductors from the... Semiconductor, Inc. received countervailable subsidies during the period of review. If these preliminary...

  12. 76 FR 2336 - Dynamic Random Access Memory Semiconductors From the Republic of Korea: Final Results of...

    Science.gov (United States)

    2011-01-13

    ... International Trade Administration Dynamic Random Access Memory Semiconductors From the Republic of Korea: Final... on dynamic random access memory semiconductors from the Republic of Korea for the period January 1... net subsidy rate for Hynix Semiconductor, Inc. is listed below in the section entitled ``Final...

  13. Rotational spectrum and dynamics of tetrahydrofuran-argon

    Energy Technology Data Exchange (ETDEWEB)

    Melandri, S.; Favero, P.G.; Caminati, W. [Dipartimento di Chimica ' G. Ciamician' dell' Universita, Via Selmi 2, I-40126 Bologna (Italy); Lopez, J.C.; Alonso, J.L. [Departamento de Quimica-Fisica, Facultad de Ciencias, Universidad de Valladolid, E-47005 Valladolid (Spain)

    1998-12-15

    The jet-cooled rotational spectrum of the tetrahydrofuran-argon molecular complex has been investigated by millimeter-wave absorption and Fourier transform microwave spectroscopies. The argon atom is located nearly over the oxygen atom, almost perpendicularly to the COC plane. Each rotational transition is split in two component lines due to the residual pseudorotational effects of the ring in the complex. The splitting between the two vibrational sublevels has been calculated to be 111.345(44) MHz. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved000.

  14. Discrete Spectrum of 2 + 1-Dimensional Nonlinear Schrödinger Equation and Dynamics of Lumps

    Directory of Open Access Journals (Sweden)

    Javier Villarroel

    2016-01-01

    Full Text Available We consider a natural integrable generalization of nonlinear Schrödinger equation to 2+1 dimensions. By studying the associated spectral operator we discover a rich discrete spectrum associated with regular rationally decaying solutions, the lumps, which display interesting nontrivial dynamics and scattering. Particular interest is placed in the dynamical evolution of the associated pulses. For all cases under study we find that the relevant dynamics corresponds to a central configuration of a certain N-body problem.

  15. Dynamic User Role Assignment in Remote Access Control

    NARCIS (Netherlands)

    Saffarian, Mohsen; Tang, Qiang; Jonker, Willem; Hartel, Pieter

    2009-01-01

    The Role-Based Access Control (RBAC) model has been widely applied to a single domain in which users are known to the administrative unit of that domain, beforehand. However, the application of the conventional RBAC model for remote access control scenarios is not straightforward. In such scenarios,

  16. Dynamic User Role Assignment in Remote Access Control

    NARCIS (Netherlands)

    Saffarian, M.; Tang, Qiang; Jonker, Willem; Hartel, Pieter H.

    2009-01-01

    The Role-Based Access Control (RBAC) model has been widely applied to a single domain in which users are known to the administrative unit of that domain, beforehand. However, the application of the conventional RBAC model for remote access control scenarios is not straightforward. In such scenarios,

  17. A PER-BASELINE, DELAY-SPECTRUM TECHNIQUE FOR ACCESSING THE 21 cm COSMIC REIONIZATION SIGNATURE

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, Aaron R.; Pober, Jonathan C. [Astronomy Department, University of California, Berkeley, CA (United States); Aguirre, James E.; Moore, David F. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA (United States); Carilli, Christopher L. [National Radio Astronomy Observatory, Socorro, NM (United States); Jacobs, Daniel C. [School of Earth and Space Exploration, Arizona State University, Tucson, AZ (United States)

    2012-09-10

    A critical challenge in measuring the power spectrum of 21 cm emission from cosmic reionization is compensating for the frequency dependence of an interferometer's sampling pattern, which can cause smooth-spectrum foregrounds to appear unsmooth and degrade the separation between foregrounds and the target signal. In this paper, we present an approach to foreground removal that explicitly accounts for this frequency dependence. We apply the delay transformation introduced in Parsons and Backer to each baseline of an interferometer to concentrate smooth-spectrum foregrounds within the bounds of the maximum geometric delays physically realizable on that baseline. By focusing on delay modes that correspond to image-domain regions beyond the horizon, we show that it is possible to avoid the bulk of smooth-spectrum foregrounds. We map the point-spread function of delay modes to k-space, showing that delay modes that are uncorrupted by foregrounds also represent samples of the three-dimensional power spectrum, and can be used to constrain cosmic reionization. Because it uses only spectral smoothness to differentiate foregrounds from the targeted 21 cm signature, this per-baseline analysis approach relies on spectrally and spatially smooth instrumental responses for foreground removal. For sufficient levels of instrumental smoothness relative to the brightness of interfering foregrounds, this technique substantially reduces the level of calibration previously thought necessary to detect 21 cm reionization. As a result, this approach places fewer constraints on antenna configuration within an array, and in particular, facilitates the adoption of configurations that are optimized for power-spectrum sensitivity. Under these assumptions, we demonstrate the potential for the Precision Array for Probing the Epoch of Reionization (PAPER) to detect 21 cm reionization at an amplitude of 10 mK{sup 2} near k {approx} 0.2 h Mpc{sup -1} with 132 dipoles in 7 months of observing.

  18. Measuring the spectrum of colored noise by dynamical decoupling.

    Science.gov (United States)

    Álvarez, Gonzalo A; Suter, Dieter

    2011-12-02

    Decoherence is one of the most important obstacles that must be overcome in quantum information processing. It depends on the qubit-environment coupling strength, but also on the spectral composition of the noise generated by the environment. If the spectral density is known, fighting the effect of decoherence can be made more effective. Applying sequences of inversion pulses to the qubit system, we developed a method for dynamical decoupling noise spectroscopy. We generate effective filter functions that probe the environmental spectral density without requiring assumptions about its shape. Comparing different pulse sequences, we recover the complete spectral density function and distinguish different contributions to the overall decoherence.

  19. Mediating Access to Headsprout® Early Reading for Children with Autism Spectrum Disorders

    Science.gov (United States)

    Plavnick, Joshua B.; Thompson, Julie L.; Englert, Carol Sue; Mariage, Troy; Johnson, Katie

    2016-01-01

    Many children with autism spectrum disorder (ASD) require instructional programs that simultaneously address academic content, interfering behavior, and potential gaps in prerequisite skills for a given curriculum. This study examined the impact of an intervention package consisting of contingent reinforcement and match-to-sample training on the…

  20. Undocumented Latino Parents' Access to Services for Their Children with Autism Spectrum Disorders: A Narrative Inquiry

    Science.gov (United States)

    Mora-Lopez, Marie

    2016-01-01

    An estimated 13 percent of children in the U.S. ages 3-21 have special needs. The Latino population is the largest minority group in the United States, and in this group there is an increasing number of Latino parents with children with Autism Spectrum Disorder (ASD). The problem is that the combined negative effects of Latinos occupying three…

  1. Enhanced Access to Early Visual Processing of Perceptual Simultaneity in Autism Spectrum Disorders

    NARCIS (Netherlands)

    Falter, Christine M.; Braeutigam, Sven; Nathan, Roger; Carrington, Sarah; Bailey, Anthony J.

    2013-01-01

    We compared judgements of the simultaneity or asynchrony of visual stimuli in individuals with autism spectrum disorders (ASD) and typically-developing controls using Magnetoencephalography (MEG). Two vertical bars were presented simultaneously or non-simultaneously with two different stimulus onset

  2. 75 FR 44283 - In the Matter of Certain Dynamic Random Access Memory Semiconductors and Products Containing Same...

    Science.gov (United States)

    2010-07-28

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION In the Matter of Certain Dynamic Random Access Memory Semiconductors and Products Containing Same... within the United States after importation of certain dynamic random access memory semiconductors...

  3. 75 FR 20564 - Dynamic Random Access Memory Semiconductors from the Republic of Korea: Extension of Time Limit...

    Science.gov (United States)

    2010-04-20

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE International Trade Administration Dynamic Random Access Memory Semiconductors from the Republic of Korea... administrative review of the countervailing duty order on dynamic random access memory semiconductors from...

  4. Baryon spectrum analysis using Dirac's covariant constraint dynamics

    Science.gov (United States)

    Whitney, Joshua F.; Crater, Horace W.

    2014-01-01

    We present a relativistic quark model for the baryons that combines three related relativistic formalisms. The three-body constraint formalism of Sazdjian is used to recast three relativistic two-body equations for the three pairs of interacting quarks into a single relativistically covariant three-body equation for the bound state energies, having a Schrodinger-like structure. The two-body equations are the two-body Dirac equations of constraint dynamics derived by Crater and Van Alstine for combined world vector and scalar interactions providing the necessary spin dependent and spin independent interaction terms. The minimal quasipotential formalism of Todorov is used to provide an invariant framework for the vector and scalar dynamics used in the two-body Dirac equations into which is inserted a local simplified version of the Richardson potential. The spectral results are analyzed and compared to experiment using a best fit method and several different algorithms, including a gradient approach, and a Monte Carlo method.

  5. On the scalability of cognitive radio: : Assessing the commercial viability of secondary spectrum access

    OpenAIRE

    Zander, Jens; Rasmussen, Lars K.; Sung, Ki Won; Maehoenen, Petri; Petrova, Marina; Jantti, Riku; Kronander, Jonas

    2013-01-01

    We report results from the recently finished QUASAR project, which has studied overall system aspects of cognitive radio technologies and has paid attention particularly to the economic viability of different use cases. We find that successful secondary sharing goes far beyond the detection of spectrum holes. Large-scale commercial success requires that secondary systems are scalable so that a large number of users can be served in an economically viable fashion. Our key finding is that secon...

  6. Dynamic spectrum allocations in multi-cells and intra-cell of cognitive network to enhance system performance

    Institute of Scientific and Technical Information of China (English)

    Su Xi; Shen Shuqun; Li Zheng; Zhang Lei

    2010-01-01

    In this study,we propose new dynamic spectrum allocations in multi-cells and intra-cell of cognitive network to enhance system performance in terms of decreasing probability of interruption and spectrum handoff of communication services in a cognitive system.The inter-cells of the spectrum allocation mechanism is designed to share the risk of vacating spectrum caused by licensed incumbents re-occupying the spectrum and minimize probability of service interruption in the cognitive network.This mechanism also can guarantee fairness among multi-cells.The intra-cell of the proposed spectrum allocation is based on a service data hierarchical model and establishes a mapping mechanism between layered data and the spectrum.It can reduce probability of spectrum handoff.Finally,simulation results are given and show that the new mechanism can reduce service interruption ratio and the probability of spectrum handoff caused by licensed incumbents with reoccupying the spectrum.

  7. 77 FR 26789 - Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory Controllers and...

    Science.gov (United States)

    2012-05-07

    ... From the Federal Register Online via the Government Publishing Office ] INTERNATIONAL TRADE COMMISSION Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory Controllers and Products Containing Same; Determination Rescinding the Exclusion Order and Cease and Desist Orders...

  8. Impact of positivity and complete positivity on accessibility of Markovian dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Romano, Raffaele [Department of Mathematics, Iowa State University, Ames, IA 50011 (United States)

    2005-10-14

    We consider a two-dimensional quantum control system evolving under an entropy-increasing irreversible dynamics in the semigroup form. Considering a phenomenological approach to the dynamics, we show that the accessibility property of the system depends on whether its evolution is assumed to be positive or completely positive. In particular, we characterize the family of maps having different accessibilities and show the impact of that property on observable quantities by means of a simple physical model.

  9. ACCESS I: An Optical Transmission Spectrum of GJ 1214b Reveals a Heterogeneous Stellar Photosphere

    CERN Document Server

    Rackham, Benjamin; Apai, Dániel; López-Morales, Mercedes; Jordán, Andrés; Osip, David J; Lewis, Nikole K; Rodler, Florian; Fraine, Jonathan D; Morley, Caroline V; Fortney, Jonathan J

    2016-01-01

    GJ 1214b is the most studied sub-Neptune exoplanet to date. Recent measurements have shown its near-infrared transmission spectrum to be flat, pointing to a high-altitude opacity source in the exoplanet's atmosphere, either equilibrium condensate clouds or photochemical hazes. Many photometric observations have been reported in the optical by different groups, though simultaneous measurements spanning the entire optical regime are lacking. We present an optical transmission spectrum ($4,500-9,260$\\AA) of GJ 1214b in 14 bins measured with Magellan/IMACS repeatedly over three transits. We measure a mean planet-to-star radius ratio of ${R_{p}/R_{s} = 0.1146\\pm{2\\times10^{-4}}}$ and mean uncertainty of $\\sigma(R_{p}/R_{s})=8.7\\times10^{-4}$ in the spectral bins. The optical transit depths are shallower on average than observed in the near-infrared. We present a model for jointly incorporating the effects of a composite photosphere and atmospheric transmission (CPAT) through the exoplanet's limb, and use it to exa...

  10. A dynamic access control method based on QoS requirement

    Science.gov (United States)

    Li, Chunquan; Wang, Yanwei; Yang, Baoye; Hu, Chunyang

    2013-03-01

    A dynamic access control method is put forward to ensure the security of the sharing service in Cloud Manufacturing, according to the application characteristics of cloud manufacturing collaborative task. The role-based access control (RBAC) model is extended according to the characteristics of cloud manufacturing in this method. The constraints are considered, which are from QoS requirement of the task context to access control, based on the traditional static authorization. The fuzzy policy rules are established about the weighted interval value of permissions. The access control authorities of executable service by users are dynamically adjusted through the fuzzy reasoning based on the QoS requirement of task. The main elements of the model are described. The fuzzy reasoning algorithm of weighted interval value based QoS requirement is studied. An effective method is provided to resolve the access control of cloud manufacturing.

  11. ACCESS I: An Optical Transmission Spectrum of GJ 1214b Reveals a Heterogeneous Stellar Photosphere

    Science.gov (United States)

    Rackham, Benjamin; Espinoza, Néstor; Apai, Dániel; López-Morales, Mercedes; Jordán, Andrés; Osip, David J.; Lewis, Nikole K.; Rodler, Florian; Fraine, Jonathan D.; Morley, Caroline V.; Fortney, Jonathan J.

    2017-01-01

    GJ 1214b is the most studied sub-Neptune exoplanet to date. Recent measurements have shown its near-infrared transmission spectrum to be flat, pointing to a high-altitude opacity source in the exoplanet's atmosphere, either equilibrium condensate clouds or photochemical hazes. Many photometric observations have been reported in the optical by different groups, though simultaneous measurements spanning the entire optical regime are lacking. We present an optical transmission spectrum (4500–9260 Å) of GJ 1214b in 14 bins, measured with Magellan/IMACS repeatedly over three transits. We measure a mean planet-to-star radius ratio of {R}p/{R}s=0.1146+/- 2× {10}-4 and mean uncertainty of σ ({R}p/{R}s)=8.7× {10}-4 in the spectral bins. The optical transit depths are shallower on average than observed in the near-infrared. We present a model for jointly incorporating the effects of a composite photosphere and atmospheric transmission through the exoplanet's limb (the CPAT model), and use it to examine the cases of absorber and temperature heterogeneities in the stellar photosphere. We find the optical and near-infrared measurements are best explained by the combination of (1) photochemical haze in the exoplanetary atmosphere with a mode particle size r = 0.1 μm and haze-forming efficiency {f}{haze}=10 % and (2) faculae in the unocculted stellar disk with a temperature contrast {{Δ }}T={354}-46+46 K, assuming 3.2% surface coverage. The CPAT model can be used to assess potential contributions of heterogeneous stellar photospheres to observations of exoplanet transmission spectra, which will be important for searches for spectral features in the optical.

  12. Comparison of path integral molecular dynamics methods for the infrared absorption spectrum of liquid water

    Science.gov (United States)

    Habershon, Scott; Fanourgakis, George S.; Manolopoulos, David E.

    2008-08-01

    The ring polymer molecular dynamics (RPMD) and partially adiabatic centroid molecular dynamics (PA-CMD) methods are compared and contrasted in an application to the infrared absorption spectrum of a recently parametrized flexible, polarizable, Thole-type potential energy model for liquid water. Both methods predict very similar spectra in the low-frequency librational and intramolecular bending region at wavenumbers below 2500 cm-1. However, the RPMD spectrum is contaminated in the high-frequency O-H stretching region by contributions from the internal vibrational modes of the ring polymer. This problem is avoided in the PA-CMD method, which adjusts the elements of the Parrinello-Rahman mass matrix so as to shift the frequencies of these vibrational modes beyond the spectral range of interest. PA-CMD does not require any more computational effort than RPMD and it is clearly the better of the two methods for simulating vibrational spectra.

  13. The Influence of Chain Dynamics on theFar-Infrared Spectrum of Liquid Methanol

    Energy Technology Data Exchange (ETDEWEB)

    Woods, K.N.; /Stanford U., Phys. Dept.; Wiedemann, H.; /SLAC, SSRL

    2005-07-11

    Far-infrared absorption spectroscopy is used to investigate the low frequency ({center_dot} 100 cm{sup -1}) intermolecular interactions in liquid methanol. Using an intense source of far-infrared radiation, modes are elucidated at approximately 30 cm{sup -1} and 70 cm{sup -1} in the absorption spectrum. These modes are believed to arise from intermolecular bending and librational motions respectively and are successfully reproduced in an ab initio molecular dynamics simulation of methanol.

  14. Piping benchmark problems. Volume 1. Dynamic analysis uniform support motion response spectrum method

    Energy Technology Data Exchange (ETDEWEB)

    Bezler, P.; Hartzman, M.; Reich, M.

    1980-08-01

    A set of benchmark problems and solutions have been developed for verifying the adequacy of computer programs used for dynamic analysis and design of nuclear piping systems by the Response Spectrum Method. The problems range from simple to complex configurations which are assumed to experience linear elastic behavior. The dynamic loading is represented by uniform support motion, assumed to be induced by seismic excitation in three spatial directions. The solutions consist of frequencies, participation factors, nodal displacement components and internal force and moment components. Solutions to associated anchor point motion static problems are not included.

  15. Access to specialty care in autism spectrum disorders-a pilot study of referral source

    Directory of Open Access Journals (Sweden)

    West Therese

    2011-05-01

    Full Text Available Abstract Background In the United States, a medical home model has been shown to improve the outcomes for children with special health care needs. As part of this model, primary care physicians provide comprehensive medical care that includes identification of delayed and/or atypical development in children and coordination of care with specialists. However, it is not clear if families of children with Autism Spectrum Disorder (ASD rely on the medical home model for care of their child to the same extent as families of children with other special health care needs. This study aims to add to the understanding of medical care for children with ASD by examining the referral source for specialty care. Methods This retrospective study was accomplished by evaluating parent completed intake data for children with ASD compared to those with other neurological disorders in a single physician Pediatric Neurology Practice at a major urban medical center in Northern New Jersey. To account for referral bias, a similar comparison study was conducted using a multispecialty ASD practice at the same medical center. Parent reported "source of referral" and "reason for the referral" of 189 ASD children and 108 non-ASD neurological disordered children were analyzed. Results The specialty evaluations of ASD were predominantly parent initiated. There were significantly less referrals received from primary care physicians for children with ASD compared to children with other neurodevelopmental disorders. Requirement of an insurance referral was not associated with a primary care physician prompted specialty visit.We identified different patterns of referral to our specialty clinics for children with ASD vs. children with other neurolodevelopmental disorders. Conclusion The majority of the families of children with ASD evaluated at our autism center did not indicate that a primary care physician initiated the specialty referral. This study suggests that families of

  16. 基于图型博弈的动态频谱分配算法%Dynamic spectrum allocation algorithm based on graphical game

    Institute of Scientific and Technical Information of China (English)

    刘觉夫; 杨将; 朱丙虎; 胡静

    2016-01-01

    针对在 Underlay频谱共享方式下的认知无线网络动态频谱分配问题,为提高认知用户接入频谱的概率并最大化认知无线网络的吞吐量,提出一种分布式动态频谱分配算法。考虑认知用户之间干扰关系的独立性,建立一种图型博弈模型,设计效用函数,引入价格函数量化对主用户的干扰影响,理论验证该模型纳什均衡的存在性。仿真实验结果表明,该算法收敛速度快,可以增大认知用户接入频谱的概率,提高网络吞吐量。%A distributed algorithm was designed for dynamic spectrum allocation for the cognitive users coexisting with primary users in an Underlay spectrum sharing paradigm.Considering the interference independence between cognitive radio users,a graphical game model was established.To quantify interference effects of cognitive user on primary users,the price function was brought into the utility function.And in this game,the existence of pure strategy Nash equilibrium was proved theoretically.To maximize cognitive radio network throughput and increase the probability of the cognitive users’access to spectrum,a distribu-ted dynamic spectrum allocation algorithm was proposed.Simulation results show that the algorithm converges faster and increases the probability of the cognitive users’access to spectrum and maximizes the throughput of the networks.

  17. Singular spectrum analysis in nonlinear dynamics, with applications to paleoclimatic time series

    Science.gov (United States)

    Vautard, R.; Ghil, M.

    1989-01-01

    Two dimensions of a dynamical system given by experimental time series are distinguished. Statistical dimension gives a theoretical upper bound for the minimal number of degrees of freedom required to describe the attractor up to the accuracy of the data, taking into account sampling and noise problems. The dynamical dimension is the intrinsic dimension of the attractor and does not depend on the quality of the data. Singular Spectrum Analysis (SSA) provides estimates of the statistical dimension. SSA also describes the main physical phenomena reflected by the data. It gives adaptive spectral filters associated with the dominant oscillations of the system and clarifies the noise characteristics of the data. SSA is applied to four paleoclimatic records. The principal climatic oscillations and the regime changes in their amplitude are detected. About 10 degrees of freedom are statistically significant in the data. Large noise and insufficient sample length do not allow reliable estimates of the dynamical dimension.

  18. The Influence of Chain Dynamics on the Far Infrared Spectrum of Liquid Methanol-Water Mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Woods, K.N.; /Stanford U., Phys. Dept.; Wiedemann, H.; /SLAC, SSRL

    2005-07-12

    Far-infrared absorption spectroscopy has been used to study the low frequency ({center_dot} 100 cm{sup -1}) intermolecular modes of methanol in mixtures with water. With the aid of a first principles molecular dynamics simulation on an equivalent system, a detailed understanding about the origin of the low frequency IR modes has been established. The total dipole spectrum from the simulation suggests that the bands appearing in the experimental spectra at approximately 55 cm{sup -1} and 70 cm{sup -1} in methanol and methanol-rich mixtures arise from both fluctuations and torsional motions occurring within the methanol hydrogen-bonded chains. The influence of these modes on both the solvation dynamics and the relaxation mechanisms in the liquid are discussed within the context of recent experimental and theoretical results that have emerged from studies focusing on the short time dynamics in the methanol hydrogen bond network.

  19. Naturally occurring broad-spectrum powdery mildw resistance in a central American tomato accession is caused by loss of Mlo function

    NARCIS (Netherlands)

    Bai, Y.; Pavan, S.N.C.; Zheng, Z.; Zappel, N.F.; Reinstadler, A.; Lotti, C.; Giovanni, de C.; Ricciardi, L.; Lindhout, P.; Visser, R.G.F.; Theres, K.; Panstruga, R.

    2008-01-01

    The resistant cherry tomato (Solanum lycopersicum var. cerasiforme) line LC-95, derived from an accession collected in Ecuador, harbors a natural allele (ol-2) that confers broad-spectrum and recessively inherited resistance to powdery mildew (Oidium neolycopersici). As both the genetic and phytopat

  20. Factors characterizing access and latency to first pharmacological treatment in Italian patients with schizophrenia, mood, and anxiety spectrum disorders.

    Science.gov (United States)

    Dell'Osso, Bernardo; Cremaschi, Laura; Palazzo, Carlotta; Suardi, Neva; Spagnolin, Gregorio; Camuri, Giulia; Benatti, Beatrice; Oldani, Lucio; Dobrea, Cristina; Arici, Chiara; Pace, Giovanna; Tiseo, Alessandra; Nahum, Ester Sembira; Castellano, Filippo; D'Urso, Nazario; Clerici, Massimo; Primavera, Diego; Carpiniello, Bernardo; Altamura, A Carlo

    2015-01-01

    Latency to first pharmacological treatment [duration of untreated illness (DUI)] in psychiatric disorders can be measured in years, with differences across diagnostic areas and relevant consequences in terms of socio-occupational functioning and outcome. Within the psychopathological onset of a specific disorder, many factors influence access and latency to first pharmacotherapy and the present study aimed to investigate such factors, through an ad-hoc developed questionnaire, in a sample of 538 patients with diagnoses of schizophrenia-spectrum disorder (SZ), mood disorder (MD), and anxiety disorder (AD). Patients with SZs showed earlier ages at onset, first diagnosis and treatment, as well as shorter DUI compared with other patients (43.17 months vs. 58.64 and 80.43 months in MD and AD; F=3.813, P=0.02). Patients with MD and AD reported more frequently onset-related stressful events, benzodiazepines as first treatment, and autonomous help seeking compared with patients with SZs. In terms of first therapist, psychiatrist referral accounted for 43.6% of the cases, progressively decreasing from SZ to MD and AD (57.6, 41.8, and 38.3%, respectively). The opposite phenomenon was observed for nonpsychiatrist clinician referrals, whereas psychologist referrals remained constant. The present findings confirm the presence of a relevant DUI in a large sample of Italian patients with different psychiatric disorders (5 years, on average), pointing out specific differences, in terms of treatment access and latency, between psychotic and affective patients. Such aspects are relevant for detection of at-risk patients and implement early intervention programs.

  1. Smart techniques in the dynamic spectrum alocation for cognitive wireless networks

    Directory of Open Access Journals (Sweden)

    Camila Salgado

    2016-09-01

    Full Text Available Objective: The objective of this work is to study the applications of different techniques of artificial intelligence and autonomous learning in the dynamic allocation of spectrum for cognitive wireless networks, especially the distributed ones. Method: The development of this work was done through the study and analysis of some of the most relevant publications in current literature through the search in indexed international journals in ISI and Scopus. Results: the most relevant techniques of artificial intelligence and autonomous learning were determined. Also, the ones with more applicability in the allocation of spectrum for cognitive wireless networks were determined, too. . Conclusions: The implementation of a technique, or set of them, depends on the needs in signal processing, compensation in response times, sample availability, storage capacity, learning ability and robustness, among others.

  2. Intramuscular and surface EMG power spectrum from dynamic and static contractions.

    Science.gov (United States)

    Christensen, H; Søgaard, K; Jensen, B R; Finsen, L; Sjøgaard, G

    1995-03-01

    During sustained static contractions an increase in the root mean square (rms) amplitude and a decrease in mean power frequency (MPF), or median power frequency (MF) of the electromyographic (EMG) signal are indicators for the development of muscle fatigue. However, when studying dynamic contractions the interpretation of these variables has been questioned. Therefore, the purpose was to compare the EMG variables recorded from a non-fatigued muscle during a slow low level dynamic contraction to those during a static contraction of similar force level. Surface and intramuscular EMG registrations were obtained from the brachial biceps muscle during: (a) a static isotonic contraction, (b) a dynamic contraction and (c) a static anisotonic contraction. During contractions (a) and (b) the recruitment pattern was analysed using the precision decomposition method. No differences in rms, MPF or MF between the dynamic and static contractions or between the concentric and eccentric phase of the dynamic contraction were found. Furthermore 60% of the identified motor units were active both in the concentric and the eccentric phase. This indicates that motor control during a slow dynamic contraction at low force level does not influence the power spectrum. We suggest that in occupational studies a possible muscle fatigue development with time can be estimated using EMG recordings from the work tasks.

  3. Impaired social brain network for processing dynamic facial expressions in autism spectrum disorders

    Directory of Open Access Journals (Sweden)

    Sato Wataru

    2012-08-01

    Full Text Available Abstract Background Impairment of social interaction via facial expressions represents a core clinical feature of autism spectrum disorders (ASD. However, the neural correlates of this dysfunction remain unidentified. Because this dysfunction is manifested in real-life situations, we hypothesized that the observation of dynamic, compared with static, facial expressions would reveal abnormal brain functioning in individuals with ASD. We presented dynamic and static facial expressions of fear and happiness to individuals with high-functioning ASD and to age- and sex-matched typically developing controls and recorded their brain activities using functional magnetic resonance imaging (fMRI. Result Regional analysis revealed reduced activation of several brain regions in the ASD group compared with controls in response to dynamic versus static facial expressions, including the middle temporal gyrus (MTG, fusiform gyrus, amygdala, medial prefrontal cortex, and inferior frontal gyrus (IFG. Dynamic causal modeling analyses revealed that bi-directional effective connectivity involving the primary visual cortex–MTG–IFG circuit was enhanced in response to dynamic as compared with static facial expressions in the control group. Group comparisons revealed that all these modulatory effects were weaker in the ASD group than in the control group. Conclusions These results suggest that weak activity and connectivity of the social brain network underlie the impairment in social interaction involving dynamic facial expressions in individuals with ASD.

  4. Accessibility of dynamic web applications with emphasis on visually impaired users

    Directory of Open Access Journals (Sweden)

    Kingsley Okoye

    2014-09-01

    Full Text Available As the internet is fast migrating from static web pages to dynamic web pages, the users with visual impairment find it confusing and challenging when accessing the contents on the web. There is evidence that dynamic web applications pose accessibility challenges for the visually impaired users. This study shows that a difference can be made through the basic understanding of the technical requirement of users with visual impairment and addresses a number of issues pertinent to the accessibility needs for such users. We propose that only by designing a framework that is structurally flexible, by removing unnecessary extras and thereby making every bit useful (fit-for-purpose, will visually impaired users be given an increased capacity to intuitively access e-contents. This theory is implemented in a dynamic website for the visually impaired designed in this study. Designers should be aware of how the screen reading software works to enable them make reasonable adjustments or provide alternative content that still corresponds to the objective content to increase the possibility of offering faultless service to such users. The result of our research reveals that materials can be added to a content repository or re-used from existing ones by identifying the content types and then transforming them into a flexible and accessible one that fits the requirements of the visually impaired through our method (no-frill + agile methodology rather than computing in advance or designing according to a given specification.

  5. Adaptive coded spreading OFDM signal for dynamic-λ optical access network

    Science.gov (United States)

    Liu, Bo; Zhang, Lijia; Xin, Xiangjun

    2015-12-01

    This paper proposes and experimentally demonstrates a novel adaptive coded spreading (ACS) orthogonal frequency division multiplexing (OFDM) signal for dynamic distributed optical ring-based access network. The wavelength can be assigned to different remote nodes (RNs) according to the traffic demand of optical network unit (ONU). The ACS can provide dynamic spreading gain to different signals according to the split ratio or transmission length, which offers flexible power budget for the network. A 10×13.12 Gb/s OFDM access with ACS is successfully demonstrated over two RNs and 120 km transmission in the experiment. The demonstrated method may be viewed as one promising for future optical metro access network.

  6. A Self-Learning MAC Protocol for Energy Harvesting and Spectrum Access in Cognitive Radio Sensor Networks

    Directory of Open Access Journals (Sweden)

    Mohammed Hawa

    2016-01-01

    Full Text Available The fusion of Wireless Sensor Networks (WSNs and Cognitive Radio Networks (CRNs into Cognitive Radio Sensor Networks (CRSNs is quite an attractive proposal, because it allows a distributed set of low-powered sensor nodes to opportunistically access spectrum bands that are underutilized by their licensed owners (called primary users (PUs. In addition, when the PUs are actively transmitting in their own bands, sensor nodes can switch to energy harvesting mode to obtain their energy needs (for free, to achieve almost perpetual life. In this work, we present a novel and fully distributed MAC protocol, called S-LEARN, that allows sensor nodes in a CRSN to entwine their RF energy harvesting and data transmission activities, while intelligently addressing the issue of disproportionate difference between the high power necessary for the node to transmit data packets and the small amount of power it can harvest wirelessly from the environment. The presented MAC protocol can improve both the network throughput and total harvested energy, while being robust to changes in the network configuration. Moreover, S-LEARN can keep the cost of the system low, and it avoids the pitfalls from which centralized systems suffer.

  7. 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.

  8. A METHOD FOR CALCULATING THE LYAPUNOV EXPONENT SPECTRUM OF A PERIODICALLY EXCITED ON-AUTONOMOUS DYNAMICAL SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Cheng Changjun; Fan Xiaojun

    2000-01-01

    The relation between the Lyapunov exponent spectrun of a periodically excited non-autono mous dynamical system and the Lyapunov exponent spectrum of the corresponding autonomous system is given and the validity of the relation is verified theoretically and computationally. A direct method for calculating the Lyapunov exponent spectrum of non-autonomous dynamical systems is suggested in this paper, which makes it more convenient to calculate the Lyapunov exponent spectrum of the dynamical system periodically excited. Following the defi nition of the Lyapunov dimension D(LA) of the autonomous system, the definition of the Lyapunov dimension Dl of the non-autonomous dynamical system is also given, and the difference be- tween them is the integer 1, namely, D(A)L - DL = 1. For a quasi-poriodically excited dynamical system, similar conclusions are formed.

  9. RF spectrum sensing in CMOS exploiting crosscorrelation

    NARCIS (Netherlands)

    Oude Alink, Mark Stefan

    2013-01-01

    The introduction of new wireless services, the demand for higher datarates, and higher traffic volumes call for a more efficient use of the RF spectrum than what is currently possible with static frequency allocation. Dynamic spectrum access offers a more efficient use by allowing unlicensed users t

  10. Dynamic Programming Used to Align Protein Structures with a Spectrum Is Robust

    Directory of Open Access Journals (Sweden)

    Allen Holder

    2013-11-01

    Full Text Available Several efficient algorithms to conduct pairwise comparisons among large databases of protein structures have emerged in the recent literature. The central theme is the design of a measure between the Cα atoms of two protein chains, from which dynamic programming is used to compute an alignment. The efficiency and efficacy of these algorithms allows large-scale computational studies that would have been previously impractical. The computational study herein shows that the structural alignment algorithm eigen-decomposition alignment with the spectrum (EIGAs is robust against both parametric and structural variation.

  11. Software architecture design for a dynamic spectrum allocation-enabled cognitive radio testbed

    DEFF Research Database (Denmark)

    Tonelli, Oscar; Berardinelli, Gilberto; Cattoni, Andrea Fabio

    2011-01-01

    The evolution of wireless communications is bringing into reality the dense deployment of femto and local area cells, which represents a challenging scenario for proving the effectiveness of Cognitive Radio (CR) frameworks. In particular the Dynamic Spectrum Allocation (DSA) paradigm aims...... at solving the resource allocation problem in a fully autonomous way. While in both CR and standardization lot of effort has been spent in developing efficient DSA algorithms, their research-oriented software radio implementation is still disregarded. In this paper, the design approach used......: preliminary results show a computational load compatible with nowadays Commercial-Off-The-Shelf computers....

  12. Dynamic Spectrum Sharing Models for Cognitive Radio Aided Ad Hoc Networks and Their Performance Analysis

    OpenAIRE

    2011-01-01

    In this paper, two dynamic spectrum sharing models are proposed, namely a Markov-chain model and a queue-based model in order, to evaluate the performance of CRAHNs, where the shared Primary Channels (PCs) are complemented by unshared Secondary Channels (SCs). The new contribution of this paper is as follows. Firstly, our Markov-chain model is extendable to any practical number of PCs and SCs and remains accurate for any practical Primary User (PU) and Secondary User (SU) tele-traffic intensi...

  13. Resource management for energy and spectrum harvesting sensor networks

    CERN Document Server

    Zhang, Deyu; Zhou, Haibo; Shen, Xuemin (Sherman)

    2017-01-01

    This SpringerBrief offers a comprehensive review and in-depth discussion of the current research on resource management. The authors explain how to best utilize harvested energy and temporally available licensed spectrum. Throughout the brief, the primary focus is energy and spectrum harvesting sensor networks (ESHNs) including energy harvesting (EH)-powered spectrum sensing and dynamic spectrum access. To efficiently collect data through the available licensed spectrum, this brief examines the joint management of energy and spectrum. An EH-powered spectrum sensing and management scheme for Heterogeneous Spectrum Harvesting Sensor Networks (HSHSNs) is presented in this brief. The scheme dynamically schedules the data sensing and spectrum access of sensors in ESHSNs to optimize the network utility, while considering the stochastic nature of EH process, PU activities and channel conditions. This brief also provides useful insights for the practical resource management scheme design for ESHSNs and motivates a ne...

  14. PROBABILISTIC PERCEPTION, EMPATHY AND DYNAMIC HOMEOSTASIS: INSIGHTS IN AUTISM SPECTRUM DISORDERS AND CONDUCT DISORDERS

    Directory of Open Access Journals (Sweden)

    Jean Marc eGuile

    2014-01-01

    Full Text Available Homeostasis is not a permanent and stable state but instead results from conflicting forces. Therefore infants have to engage in dynamic exchanges with their environment, on biological, cognitive and affective domains. Empathy is an adaptive response to these environmental challenges, which contributes to reaching proper dynamic homeostasis and development. Empathy relies on implicit interactive processes, namely probabilistic perception and synchrony, which will be reviewed in the article. If typically-developped neonates are fully equipped to automatically and synchronously interact with their human environment, Conduct Disorders (CD and Autism Spectrum Disorders (ASD present with impairments in empathetic communication, e.g. emotional arousal and facial emotion processing . In addition sensorimotor resonance is lacking in ASD and emotional concern impaired in CD with Callous-Unemotional traits.

  15. An effective field theory during inflation II: stochastic dynamics and power spectrum suppression

    CERN Document Server

    Boyanovsky, D

    2015-01-01

    We obtain the non-equilibrium effective action of an inflaton like scalar field --the system-- by tracing over sub Hubble degrees of freedom of ``environmental'' light scalar fields. The effective action is stochastic leading to effective Langevin equations of motion for the fluctuations of the inflaton-like field, with self-energy corrections and stochastic noise correlators that obey a de Sitter space-time analog of a fluctuation dissipation relation. We solve the Langevin equation implementing a dynamical renormalization group resummation of the leading secular terms and obtain the corrections to the power spectrum of super Hubble fluctuations of the inflaton field, $\\mathcal{P}(k;\\eta) = \\mathcal{P}_0(k)\\,e^{-\\gamma(k;\\eta)}$ where $\\mathcal{P}_0(k)$ is the nearly scale invariant power spectrum in absence of coupling. $\\gamma(k;\\eta)>0$ describes the suppression of the power spectrum, it features Sudakov-type double logarithms and entails violations of scale invariance. We also obtain the effective action...

  16. Interpreting the power spectrum of Dansgaard-Oeschger events via stochastic dynamical systems

    Science.gov (United States)

    Mitsui, Takahito; Lenoir, Guillaume; Crucifix, Michel

    2017-04-01

    Dansgaard-Oeschger (DO) events are abrupt climate shifts, which are particularly pronounced in the North Atlantic region during glacial periods [Dansgaard et al. 1993]. The signals are most clearly found in δ 18O or log [Ca2+] records of Greenland ice cores. The power spectrum S(f) of DO events has attracted attention over two decades with debates on the apparent 1.5-kyr periodicity [Grootes & Stuiver 1997; Schultz et al. 2002; Ditlevsen et al. 2007] and scaling property over several time scales [Schmitt, Lovejoy, & Schertzer 1995; Rypdal & Rypdal 2016]. The scaling property is written most simply as S(f)˜ f-β , β ≈ 1.4. However, physical as well as underlying dynamics of the periodicity and the scaling property are still not clear. Pioneering works for modelling the spectrum of DO events are done by Cessi (1994) and Ditlevsen (1999), but their model-data comparisons of the spectra are rather qualitative. Here, we show that simple stochastic dynamical systems can generate power spectra statistically consistent with the observed spectra over a wide range of frequency from orbital to the Nyquist frequency (=1/40 yr-1). We characterize the scaling property of the spectrum by defining a local scaling exponentβ _loc. For the NGRIP log [Ca2+] record, the local scaling exponent β _loc increases from ˜ 1 to ˜ 2 as the frequency increases from ˜ 1/5000 yr-1 to ˜ 1/500 yr-1, and β _loc decreases toward zero as the frequency increases from ˜ 1/500 yr-1 to the Nyquist frequency. For the δ 18O record, the local scaling exponent β _loc increases from ˜ 1 to ˜ 1.5 as the frequency increases from ˜ 1/5000 yr^{-1 to ˜ 1/1000 yr-1, and β _loc decreases toward zero as the frequency increases from ˜ 1/1000 yr-1 to the Nyquist frequency. This systematic breaking of a single scaling is reproduced by the simple stochastic models. Especially, the models suggest that the flattening of the spectra starting from multi-centennial scale and ending at the Nyquist frequency

  17. 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...

  18. Design and Implementation of File Access and Control System Based on Dynamic Web

    Institute of Scientific and Technical Information of China (English)

    GAO Fuxiang; YAO Lan; BAO Shengfei; YU Ge

    2006-01-01

    A dynamic Web application, which can help the departments of enterprise to collaborate with each other conveniently, is proposed. Several popular design solutions are introduced at first. Then, dynamic Web system is chosen for developing the file access and control system. Finally, the paper gives the detailed process of the design and implementation of the system, which includes some key problems such as solutions of document management and system security. Additionally, the limitations of the system as well as the suggestions of further improvement are also explained.

  19. An Adaptive Channel Access Method for Dynamic Super Dense Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Chunyang Lei

    2015-12-01

    Full Text Available Super dense and distributed wireless sensor networks have become very popular with the development of small cell technology, Internet of Things (IoT, Machine-to-Machine (M2M communications, Vehicular-to-Vehicular (V2V communications and public safety networks. While densely deployed wireless networks provide one of the most important and sustainable solutions to improve the accuracy of sensing and spectral efficiency, a new channel access scheme needs to be designed to solve the channel congestion problem introduced by the high dynamics of competing nodes accessing the channel simultaneously. In this paper, we firstly analyzed the channel contention problem using a novel normalized channel contention analysis model which provides information on how to tune the contention window according to the state of channel contention. We then proposed an adaptive channel contention window tuning algorithm in which the contention window tuning rate is set dynamically based on the estimated channel contention level. Simulation results show that our proposed adaptive channel access algorithm based on fast contention window tuning can achieve more than 95 % of the theoretical optimal throughput and 0 . 97 of fairness index especially in dynamic and dense networks.

  20. An Adaptive Channel Access Method for Dynamic Super Dense Wireless Sensor Networks.

    Science.gov (United States)

    Lei, Chunyang; Bie, Hongxia; Fang, Gengfa; Zhang, Xuekun

    2015-12-03

    Super dense and distributed wireless sensor networks have become very popular with the development of small cell technology, Internet of Things (IoT), Machine-to-Machine (M2M) communications, Vehicular-to-Vehicular (V2V) communications and public safety networks. While densely deployed wireless networks provide one of the most important and sustainable solutions to improve the accuracy of sensing and spectral efficiency, a new channel access scheme needs to be designed to solve the channel congestion problem introduced by the high dynamics of competing nodes accessing the channel simultaneously. In this paper, we firstly analyzed the channel contention problem using a novel normalized channel contention analysis model which provides information on how to tune the contention window according to the state of channel contention. We then proposed an adaptive channel contention window tuning algorithm in which the contention window tuning rate is set dynamically based on the estimated channel contention level. Simulation results show that our proposed adaptive channel access algorithm based on fast contention window tuning can achieve more than 95 % of the theoretical optimal throughput and 0 . 97 of fairness index especially in dynamic and dense networks.

  1. Hilbert spectrum and intrinsic oscillation mode of dynamic response of a bilinear SDOF system: influence of harmonic excitation amplitude

    Institute of Scientific and Technical Information of China (English)

    Zhang Yushan; Liang Jianwen; Hu Yuxian

    2005-01-01

    Under harmonic wave excitation, the dynamic response of a bilinear SDOF system can be expressed by the Hilbert spectrum. The Hilbert spectrum can be formulated by (1) the inter-wave combination mechanism between the steady response and the transient response when the system behaves linearly, or (2) the intra-wave modulation mechanism embedded in one intrinsic mode function (IMF) component when the system behaves nonlinearly. The temporal variation of the instantaneous frequency of the IMF component is consistent with the system nonlinear behavior of yielding and unloading. As a thorough study of this fundamental structural dynamics problem, this article investigates the influence of the amplitude of the harmonic wave excitation on the Hilbert spectrum and the intrinsic oscillatory mode of the dynamic response of a bilinear SDOF system.

  2. Validation of computational fluid dynamics-based analysis to evaluate hemodynamic significance of access stenosis.

    Science.gov (United States)

    Hoganson, David M; Hinkel, Cameron J; Chen, Xiaomin; Agarwal, Ramesh K; Shenoy, Surendra

    2014-01-01

    Stenosis in a vascular access circuit is the predominant cause of access dysfunction. Hemodynamic significance of a stenosis identified by angiography in an access circuit is uncertain. This study utilizes computational fluid dynamics (CFD) to model flow through arteriovenous fistula to predict the functional significance of stenosis in vascular access circuits. Three-dimensional models of fistulas were created with a range of clinically relevant stenoses using SolidWorks. Stenoses diameters ranged from 1.0 to 3.0 mm and lengths from 5 to 60 mm within a fistula diameter of 7 mm. CFD analyses were performed using a blood model over a range of blood pressures. Eight patient-specific stenoses were also modeled and analyzed with CFD and the resulting blood flow calculations were validated by comparison with brachial artery flow measured by duplex ultrasound. Predicted flow rates were derived from CFD analysis of a range of stenoses. These stenoses were modeled by CFD and correlated with the ultrasound measured flow rate through the fistula of eight patients. The calculated flow rate using CFD correlated within 20% of ultrasound measured flow for five of eight patients. The mean difference was 17.2% (ranged from 1.3% to 30.1%). CFD analysis-generated flow rate tables provide valuable information to assess the functional significance of stenosis detected during imaging studies. The CFD study can help in determining the clinical relevance of a stenosis in access dysfunction and guide the need for intervention.

  3. 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.

  4. [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.

  5. Dynamic Spectrum Sharing Among Repeatedly Interacting Selfish Users With Imperfect Monitoring

    CERN Document Server

    Xiao, Yuanzhang

    2012-01-01

    In this paper, we develop a novel design framework for dynamic spectrum sharing among secondary users (SU) who adjust their power allocation while satisfying under interference temperature (IT) constraints imposed by primary users. The considered interaction among the secondary users is characterized by the following three unique features. First, SUs are selfish and aim to maximize their own long-term payoffs from utilizing the network rather than obeying the prescribed allocation of a centralized controller. Second, SUs are interacting with each other repeatedly and they can coexist in the system for a long time as long as the IT constraints are not violated. Third, SUs have imperfect and limited monitoring ability: they only observe whether the IT constraints are violated, and their observation is imperfect due to the erroneous measurements. To capture these unique features, we model the interaction of secondary users as a repeated game with imperfect monitoring. We first characterize the set of Pareto opti...

  6. Vibrational spectrum at a water surface: a hybrid quantum mechanics/molecular mechanics molecular dynamics approach.

    Science.gov (United States)

    Ishiyama, Tatsuya; Takahashi, Hideaki; Morita, Akihiro

    2012-03-28

    A hybrid quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) simulation is applied to the calculation of surface orientational structure and vibrational spectrum (second-order nonlinear susceptibility) at the vapor/water interface for the first time. The surface orientational structure of the QM water molecules is consistent with the previous MD studies, and the calculated susceptibility reproduces the experimentally reported one, supporting the previous results using the classical force field MD simulation. The present QM/MM MD simulation also demonstrates that the positive sign of the imaginary part of the second-order nonlinear susceptibility at the lower hydrogen bonding OH frequency region originates not from individual molecular orientational structure, but from cooperative electronic structure through the hydrogen bonding network.

  7. Telomeric overhang length determines structural dynamics and accessibility to telomerase and ALT associated proteins

    Science.gov (United States)

    Hwang, Helen; Kreig, Alex; Calvert, Jacob; Lormand, Justin; Kwon, Yongho; Daley, James M.; Sung, Patrick; Opresko, Patricia L.; Myong, Sua

    2014-01-01

    The G-rich single stranded DNA at the 3′ end of human telomeres can self-fold into G-quaduplex (GQ). However, telomere lengthening by telomerase or the recombination-based alternative lengthening of telomere (ALT) mechanism requires protein loading on the overhang. Using single molecule fluorescence spectroscopy we discovered that lengthening the telomeric overhang also increased the rate of dynamic exchanges between structural conformations. Overhangs with five to seven TTAGGG repeats, compared to four repeats, showed much greater dynamics and accessibility to telomerase binding and activity, and loading of the ALT-associated proteins RAD51, WRN and BLM. Although the eight repeats are highly dynamic, they can fold into two GQs, which limited protein accessibility. In contrast, the telomere-specific protein, POT1 is unique in that it binds independently of repeat number. Our results suggest that the telomeric overhang length and dynamics may contribute to the regulation of telomere extension via telomerase action and the ALT mechanism. PMID:24836024

  8. Universal model for collective access patterns in the Internet traffic dynamics: A superstatistical approach

    Science.gov (United States)

    Tamazian, A.; Nguyen, V. D.; Markelov, O. A.; Bogachev, M. I.

    2016-07-01

    We suggest a universal phenomenological description for the collective access patterns in the Internet traffic dynamics both at local and wide area network levels that takes into account erratic fluctuations imposed by cooperative user behaviour. Our description is based on the superstatistical approach and leads to the q-exponential inter-session time and session size distributions that are also in perfect agreement with empirical observations. The validity of the proposed description is confirmed explicitly by the analysis of complete 10-day traffic traces from the WIDE backbone link and from the local campus area network downlink from the Internet Service Provider. Remarkably, the same functional forms have been observed in the historic access patterns from single WWW servers. The suggested approach effectively accounts for the complex interplay of both “calm” and “bursty” user access patterns within a single-model setting. It also provides average sojourn time estimates with reasonable accuracy, as indicated by the queuing system performance simulation, this way largely overcoming the failure of Poisson modelling of the Internet traffic dynamics.

  9. Coordinated Dynamic Spectrum Allocation Mechanism Design Based on Combined Priority Scheduling%基于联合优先级调度的协作动态频谱分配机制设计

    Institute of Scientific and Technical Information of China (English)

    王凡; 姚富强; 赵杭生; 冯少栋; 张建照

    2011-01-01

    在协作频谱接入过程中,共享频谱各网络中的频谱需求呈现高度动态性,现有机制难以兼顾分组传输时延和服务公平性.针对这一问题,提出一种基于联合优先级调度的协作动态频谱分配机制.将频谱分配问题建模为比例公平模型并联合网络的服务等级和用频请求的到达时间为各网络设定动态服务优先级,解得分配结果后,基于分配频谱的中心频率与需求频谱的中心频率最近的原则将频谱资源分配给各网络.仿真结果表明,与已有的基于网络固定优先级调度、基于网络动态优先级调度和基于用频请求动态优先级调度的协作频谱分配机制相比,本机制能够更好地保证网络获取频谱的公平性,并且在分组传输时延性能上有所改进.%In coordinated spectrum access.when the networks sharing the same spectrum have highly varying spectrum requirement,existing mechanisms cannot provide better performance of end-to-end time delay and fairness. To tackle this problem, a coordinated dynamic spectrum allocation mechanism based on combined priority scheduling was proposed. The mechanism models the spectrum allocation as proportional fairness and set dynamic priority to networks by combining the service grade of networks and the arrival time of spectrum requirement. After figuring out the results of the proportional fairness model,the mechanism allocates spectrum according to the results based on the criterion that the center frequency of allocated spectrum is close to the spectrum requirement The simulation results show that the proposed mechanism can provide better fairness of spectrum allocation than existing mechanisms as network(or terminal) static priority, network (or terminal) dynamic priority and request dynamic priority based coordinated dynamic spectrum allocation,and also brings improvement in terms of performance of end-to-end time delay of packet transmission.

  10. FODA: a novel efficient multiple access protocol for highly dynamic self-organizing networks

    Science.gov (United States)

    Li, Hantao; Liu, Kai; Zhang, Jun

    2005-11-01

    Based on the concept of contention reservation for polling transmission and collision prevention strategy for collision resolution, a fair on-demand access (FODA) protocol for supporting node mobility and multihop architecture in highly dynamic self-organizing networks is proposed. In the protocol, a distributed clustering network architecture formed by self-organizing algorithm and a main idea of reserving channel resources to get polling service are adopted, so that the hidden terminal (HT) and exposed terminal (ET) problems existed in traffic transmission due to multihop architecture and wireless transmission can be eliminated completely. In addition, an improved collision prevention scheme based on binary countdown algorithm (BCA), called fair collision prevention (FCP) algorithm, is proposed to greatly eliminate unfair phenomena existed in contention access of newly active ordinary nodes and completely resolve access collisions. Finally, the performance comparison of the FODA protocol with carrier sense multiple access with collision avoidance (CSMA/CA) and polling protocols by OPNET simulation are presented. Simulation results show that the FODA protocol can overcome the disadvantages of CSMA/CA and polling protocols, and achieve higher throughput, lower average message delay and less average message dropping rate.

  11. Reduced Recognition of Dynamic Facial Emotional Expressions and Emotion-Specific Response Bias in Children with an Autism Spectrum Disorder

    Science.gov (United States)

    Evers, Kris; Steyaert, Jean; Noens, Ilse; Wagemans, Johan

    2015-01-01

    Emotion labelling was evaluated in two matched samples of 6-14-year old children with and without an autism spectrum disorder (ASD; N = 45 and N = 50, resp.), using six dynamic facial expressions. The Emotion Recognition Task proved to be valuable demonstrating subtle emotion recognition difficulties in ASD, as we showed a general poorer emotion…

  12. Reduced Recognition of Dynamic Facial Emotional Expressions and Emotion-Specific Response Bias in Children with an Autism Spectrum Disorder

    Science.gov (United States)

    Evers, Kris; Steyaert, Jean; Noens, Ilse; Wagemans, Johan

    2015-01-01

    Emotion labelling was evaluated in two matched samples of 6-14-year old children with and without an autism spectrum disorder (ASD; N = 45 and N = 50, resp.), using six dynamic facial expressions. The Emotion Recognition Task proved to be valuable demonstrating subtle emotion recognition difficulties in ASD, as we showed a general poorer emotion…

  13. Valence Scaling of Dynamic Facial Expressions Is Altered in High-Functioning Subjects with Autism Spectrum Disorders: An FMRI Study

    Science.gov (United States)

    Rahko, Jukka S.; Paakki, Jyri-Johan; Starck, Tuomo H.; Nikkinen, Juha; Pauls, David L.; Katsyri, Jari V.; Jansson-Verkasalo, Eira M.; Carter, Alice S.; Hurtig, Tuula M.; Mattila, Marja-Leena; Jussila, Katja K.; Remes, Jukka J.; Kuusikko-Gauffin, Sanna A.; Sams, Mikko E.; Bolte, Sven; Ebeling, Hanna E.; Moilanen, Irma K.; Tervonen, Osmo; Kiviniemi, Vesa

    2012-01-01

    FMRI was performed with the dynamic facial expressions fear and happiness. This was done to detect differences in valence processing between 25 subjects with autism spectrum disorders (ASDs) and 27 typically developing controls. Valence scaling was abnormal in ASDs. Positive valence induces lower deactivation and abnormally strong activity in ASD…

  14. Undifferentiated Facial Electromyography Responses to Dynamic, Audio-Visual Emotion Displays in Individuals with Autism Spectrum Disorders

    Science.gov (United States)

    Rozga, Agata; King, Tricia Z.; Vuduc, Richard W.; Robins, Diana L.

    2013-01-01

    We examined facial electromyography (fEMG) activity to dynamic, audio-visual emotional displays in individuals with autism spectrum disorders (ASD) and typically developing (TD) individuals. Participants viewed clips of happy, angry, and fearful displays that contained both facial expression and affective prosody while surface electrodes measured…

  15. Accessing complexity: the dynamics of virus-specific T cell responses

    DEFF Research Database (Denmark)

    Doherty, P C; Christensen, Jan Pravsgaard

    2000-01-01

    The cellular dynamics of the immune system are complex and difficult to measure. Access to this problematic area has been greatly enhanced by the recent development of tetrameric complexes of MHC class I glycoprotein + peptide (tetramers) for the direct staining of freshly isolated, antigen...... of the host response to viruses. Dissection of the phenotypic, functional, and molecular diversity of CD8(+) T cell populations has been greatly facilitated. It is hoped it will also soon be possible to analyze CD4(+) T cell populations in this way. Though these are early days and there is an enormous amount...

  16. On Hamiltonian Magnetohydrodynamics: Lagrangian, Eulerian, and Dynamically Accessible Stability - Applications with Translation Symmetry

    Science.gov (United States)

    Morrison, P. J.; Andreussi, T.; Pegoraro, F.

    2016-10-01

    In a series of papers we have investigated general properties of equilibria and their stability in each of the Lagrangian, Eulerian, and Dynamically Accessible stability formulations of magnetohydrodynamics. In our latest work we compare and contrast stability results with these formulations for two applications: stratified convection and rotating pinch equilibrium configurations. The former example, emphasizes the role played entropy, while the later demonstrates the utility of a relabeling transformation that we introduced in our earlier work. Comparisons to classical works, in particular on interchange instability, are made. DOE DE-FG02-04ER-54742.

  17. Temperature effects on failure and annealing behavior in dynamic random access memories

    Science.gov (United States)

    Wilkin, N. D.; Self, C. T.

    1982-12-01

    Total dose failure levels and long time anneal characteristics of dynamic random access memories are measured while the devices are exercised under actual use conditions. These measurements were performed over the temperature range of -60 C to +70 C. The total dose failure levels are shown to decrease with increasing temperature. The anneal characteristics are shown to result in both an increase and decrease in the measured number of errors as a function of time. Finally a description of the test instrumentation and irradiation procedures are given.

  18. First measurements of Dα spectrum produced by anisotropic fast ions in the gas dynamic trap

    Science.gov (United States)

    Lizunov, A.; Anikeev, A.

    2014-11-01

    Angled injection of eight deuterium beams in gas dynamic trap (GDT) plasmas builds up the population of fast ions with the distribution function, which conserves a high degree of initial anisotropy in space, energy, and pitch angle. Unlike the Maxwellian distribution case, the fast ion plasma component in GDT cannot be exhaustively characterized by the temperature and density. The instrumentation complex to study of fast ions is comprised of motional Stark effect diagnostic, analyzers of charge exchange atoms, and others. The set of numerical codes using for equilibrium modeling is also an important tool of analysis. In the recent campaign of summer 2014, we recorded first signals from the new fast ion D-alpha diagnostic on GDT. This paper presents the diagnostic description and results of pilot measurements. The diagnostic has four lines of sight, distributed across the radius of an axially symmetric plasma column in GDT. In the present setup, a line-integrated optical signal is measured in each channel. In the transverse direction, the spatial resolution is 18 mm. Collected light comes to the grating spectrometer with the low-noise detector based on a charge-coupled device matrix. In the regime of four spectra stacked vertically on the sensor, the effective spectral resolution of measurements is approximately 0.015 nm. Exposure timing is provided by the fast optical ferroelectric crystal shutter, allowing frames of duration down to 70 μs. This number represents the time resolution of measurements. A large dynamic range of the camera permits for a measurement of relatively small light signals produced by fast ions on top of the bright background emission from the bulk plasma. The fast ion emission has a non-Gaussian spectrum featuring the characteristic width of approximately 4 nm, which can be separated from relatively narrow Gaussian lines of D-alpha and H-alpha coming from the plasma periphery, and diagnostic beam emission. The signal to noise ratio varies

  19. Accessing Rydberg-dressed interactions using many-body Ramsey dynamics

    CERN Document Server

    Mukherjee, Rick; Hazzard, Kaden R A

    2015-01-01

    We demonstrate that Ramsey spectroscopy can be used to observe Rydberg-dressed interactions. In contrast to many prior proposals, our scheme operates comfortably within experimentally measured lifetimes, and accesses a regime where quantum superpositions are crucial. The key idea is to build a spin-1/2 from one level that is Rydberg-dressed and another that is not. These levels may be hyperfine or long-lived electronic states. An Ising spin model governs the Ramsey dynamics, for which we derive an exact solution. Due to the structure of Rydberg interactions, the dynamics differs significantly from that in other spin systems. As one example, spin echo can increase the rate at which coherence decays. The results also apply to bare (undressed) Rydberg states as a special case, for which we quantitatively reproduce recent ultrafast experiments without fitting.

  20. Accessing Rydberg-dressed interactions using many-body Ramsey dynamics

    Science.gov (United States)

    Mukherjee, Rick; Killian, Thomas; Hazzard, Kaden

    2016-05-01

    We demonstrate that Ramsey spectroscopy can be used to observe Rydberg-dressed interactions in a many-body system. Our scheme operates comfortably within experimentally measured lifetimes, and accesses a regime where quantum superpositions are crucial. We build a spin-1/2 from one level that is Rydberg-dressed and another that is not. These levels may be hyperfine or long-lived electronic states. An Ising spin model governs the Ramsey dynamics, for which we derive an exact solution. Due to the structure of Rydberg interactions, the dynamics differs significantly from that in other spin systems. As one example, spin echo can increase the rate at which coherence decays. The results are relevant for the current ongoing experiments, including those at Rice University.

  1. The Facilitators, Obstacles and Needs of Individuals with Autism Spectrum Conditions Accessing Further and Higher Education: A Systematic Review

    Science.gov (United States)

    Toor, Nicky; Hanley, Terry; Hebron, Judith

    2016-01-01

    Many young adults diagnosed with autism spectrum conditions (ASC) intend to go to college and/or university, yet research suggests that these individuals find aspects of college and university life challenging. To explore the views of individuals directly affected by these challenges, a systematic review of the existing qualitative literature in…

  2. Efficient traffic grooming with dynamic ONU grouping for multiple-OLT-based access network

    Science.gov (United States)

    Zhang, Shizong; Gu, Rentao; Ji, Yuefeng; Wang, Hongxiang

    2015-12-01

    Fast bandwidth growth urges large-scale high-density access scenarios, where the multiple Passive Optical Networking (PON) system clustered deployment can be adopted as an appropriate solution to fulfill the huge bandwidth demands, especially for a future 5G mobile network. However, the lack of interaction between different optical line terminals (OLTs) results in part of the bandwidth resources waste. To increase the bandwidth efficiency, as well as reduce bandwidth pressure at the edge of a network, we propose a centralized flexible PON architecture based on Time- and Wavelength-Division Multiplexing PON (TWDM PON). It can provide flexible affiliation for optical network units (ONUs) and different OLTs to support access network traffic localization. Specifically, a dynamic ONU grouping algorithm (DGA) is provided to obtain the minimal OLT outbound traffic. Simulation results show that DGA obtains an average 25.23% traffic gain increment under different OLT numbers within a small ONU number situation, and the traffic gain will increase dramatically with the increment of the ONU number. As the DGA can be deployed easily as an application running above the centralized control plane, the proposed architecture can be helpful to improve the network efficiency for future traffic-intensive access scenarios.

  3. Relating the bipolar spectrum to dysregulation of behavioural activation: a perspective from dynamical modelling.

    Directory of Open Access Journals (Sweden)

    Arno Steinacher

    Full Text Available Bipolar Disorders affect a substantial minority of the population and result in significant personal, social and economic costs. Understanding of the causes of, and consequently the most effective interventions for, this condition is an area requiring development. Drawing upon theories of Bipolar Disorder that propose the condition to be underpinned by dysregulation of systems governing behavioural activation or approach motivation, we present a mathematical model of the regulation of behavioural activation. The model is informed by non-linear, dynamical principles and as such proposes that the transition from "non-bipolar" to "bipolar" diagnostic status corresponds to a switch from mono- to multistability of behavioural activation level, rather than an increase in oscillation of mood. Consistent with descriptions of the behavioural activation or approach system in the literature, auto-activation and auto-inhibitory feedback is inherent within our model. Comparison between our model and empirical, observational data reveals that by increasing the non-linearity dimension in our model, important features of Bipolar Spectrum disorders are reproduced. Analysis from stochastic simulation of the system reveals the role of noise in behavioural activation regulation and indicates that an increase of nonlinearity promotes noise to jump scales from small fluctuations of activation levels to longer lasting, but less variable episodes. We conclude that further research is required to relate parameters of our model to key behavioural and biological variables observed in Bipolar Disorder.

  4. Mechanism of generation of the emission bands in the dynamic spectrum of the Crab pulsar

    CERN Document Server

    Ardavan, H; Singleton, J; Pérez, M

    2008-01-01

    We show that the proportionately spaced emission bands in the dynamic spectrum of the Crab pulsar (Hankins T. H. & Eilek J. A., 2007, ApJ, 670, 693) fit the oscillations of the square of a Bessel function whose argument exceeds its order. This function has already been encountered in the analysis of the emission from a polarization current with a superluminal distribution pattern: a current whose distribution pattern rotates (with an angular frequency $\\omega$) and oscillates (with a frequency $\\Omega>\\omega$ differing from an integral multiple of $\\omega$) at the same time (Ardavan H., Ardavan A. & Singleton J., 2003, J Opt Soc Am A, 20, 2137). Using the results of our earlier analysis, we find that the dependence on frequency of the spacing and width of the observed emission bands can be quantitatively accounted for by an appropriate choice of the value of the single free parameter $\\Omega/\\omega$. In addition, the value of this parameter, thus implied by Hankins & Eilek's data, places the last ...

  5. Relating the bipolar spectrum to dysregulation of behavioural activation: a perspective from dynamical modelling.

    Science.gov (United States)

    Steinacher, Arno; Wright, Kim A

    2013-01-01

    Bipolar Disorders affect a substantial minority of the population and result in significant personal, social and economic costs. Understanding of the causes of, and consequently the most effective interventions for, this condition is an area requiring development. Drawing upon theories of Bipolar Disorder that propose the condition to be underpinned by dysregulation of systems governing behavioural activation or approach motivation, we present a mathematical model of the regulation of behavioural activation. The model is informed by non-linear, dynamical principles and as such proposes that the transition from "non-bipolar" to "bipolar" diagnostic status corresponds to a switch from mono- to multistability of behavioural activation level, rather than an increase in oscillation of mood. Consistent with descriptions of the behavioural activation or approach system in the literature, auto-activation and auto-inhibitory feedback is inherent within our model. Comparison between our model and empirical, observational data reveals that by increasing the non-linearity dimension in our model, important features of Bipolar Spectrum disorders are reproduced. Analysis from stochastic simulation of the system reveals the role of noise in behavioural activation regulation and indicates that an increase of nonlinearity promotes noise to jump scales from small fluctuations of activation levels to longer lasting, but less variable episodes. We conclude that further research is required to relate parameters of our model to key behavioural and biological variables observed in Bipolar Disorder.

  6. Shamir secret sharing scheme with dynamic access structure (SSSDAS). Case study on nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Thiyagarajan, P.; Thandra, Prasanth Kumar; Rajan, J.; Satyamurthy, S.A.V. [Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam (India). Computer Div.; Aghila, G. [National Institute of Technology, Karaikal (India). Dept. of Computer Science and Engineering

    2015-05-15

    In recent years, due to the sophistication offered by the Internet, strategic organizations like nuclear power plants are linked to the outside world communication through the Internet. The entry of outside world communication into strategic organization (nuclear power plant) increases the hacker's attempts to crack its security and to trace any information which is being sent among the top level officials. Information security system in nuclear power plant is very crucial as even small loophole in the security system will lead to a major disaster. Recent cyber attacks in nuclear power plant provoked information security professionals to look deeply into the information security aspects of strategic organizations (nuclear power plant). In these lines, Shamir secret sharing scheme with dynamic access structure (SSSDAS) is proposed in the paper which provides enhanced security by providing dynamic access structure for each node in different hierarchies. The SSSDAS algorithm can be applied to any strategic organizations with hierarchical structures. In this paper the possible scenarios where SSSDAS algorithm can be applied to nuclear power plant is explained as a case study. The proposed SSSDAS scheme identifies the wrong shares, if any, used for reconstruction of the secret. The SSSDAS scheme also address the three major security parameters namely confidentiality, authentication and integrity.

  7. THE EUROPEANISATION PROCESS AND THE PRE-ACCESSION DYNAMICS IN ROMANIA

    Directory of Open Access Journals (Sweden)

    Teodor Lucian Moga

    2011-03-01

    Full Text Available In recent years a substantial part of literature that covers topics on European integration has turned its attention to how the membership of the European Union (EU has generated and contributed to domestic reform, a process commonly known as Europeanisation. This process represents the reform of institutions, structures and policies in compliance with the requirements, policies and dynamics of the European integration mechanisms. Following the national - European interaction, countries internalise European legislation and adapt institutionally. The purpose of this paper is to analyse the Europeanisation process and also to what extent it has influenced the political and economic reform in Romania throughout the pre-accession period. Despite its essential contributions, the Europeanisation effects were less significant in Romania (especially in the early years of negotiations with Brussels compared with other Eastern European countries. And this has not been caused by the Europeanisation lack of efficiency, but mainly because of the Romanian political class reluctant to change that largely undermined the dynamics of the accession process.

  8. Spatial-Temporal dynamics of surface water flooding and consequences for emergency services accessibility

    Science.gov (United States)

    Pattison, Ian; Green, Daniel; Yu, Dapeng; Bosher, Lee; Wilby, Rob; Yang, Lili; Ryley, Tim

    2016-04-01

    and contract through the event as the inundated area makes roads in different parts of the city inaccessible through the event. These maps also allow key access roads to be identified. Key stakeholders, within the City of Leicester, have highlighted the potential benefit of such dynamic accessibility maps for their multi-agency planning and response for surface water flooding.

  9. Collective excitations in liquid DMSO : FIR spectrum, Low frequency vibrational density of states and ultrafast dipolar solvation dynamics

    CERN Document Server

    Hazra, Milan

    2016-01-01

    Valuable dynamical and structural information about neat liquid DMSO at ambient conditions can be obtained through study of low frequency vibrations in the far infrared (FIR), that is, terahertz regime. For DMSO, collective excitations as well as single molecule stretches and bends have been measured by different kinds of experiments such as OHD-RIKES and terahertz spectroscopy. In the present work we investigate the intermolecular vibrational spectrum of DMSO through three different computational techniques namely (i) the far-infra red spectrum obtained through Fourier transform of total dipole moment auto time correlation function, (ii) from Fourier transform of the translational and angular velocity time autocorrelation functions and a (iii) quenched normal mode analysis of the parent liquid at 300K. The three spectrum, although exhibit differences among each other, reveal similar features which are in good, semi-quantitative, agreement with experimental results. Study of participation ratio of the density...

  10. Cardea: Providing Support for Dynamic Resource Access in a Distributed Computing Environment

    Science.gov (United States)

    Lepro, Rebekah

    2003-01-01

    The environment framing the modem authorization process span domains of administration, relies on many different authentication sources, and manages complex attributes as part of the authorization process. Cardea facilitates dynamic access control within this environment as a central function of an inter-operable authorization framework. The system departs from the traditional authorization model by separating the authentication and authorization processes, distributing the responsibility for authorization data and allowing collaborating domains to retain control over their implementation mechanisms. Critical features of the system architecture and its handling of the authorization process differentiate the system from existing authorization components by addressing common needs not adequately addressed by existing systems. Continuing system research seeks to enhance the implementation of the current authorization model employed in Cardea, increase the robustness of current features, further the framework for establishing trust and promote interoperability with existing security mechanisms.

  11. The Zebrafish Neurophenome Database (ZND): a dynamic open-access resource for zebrafish neurophenotypic data.

    Science.gov (United States)

    Kyzar, Evan; Zapolsky, Ivan; Green, Jeremy; Gaikwad, Siddharth; Pham, Mimi; Collins, Christopher; Roth, Andrew; Stewart, Adam Michael; St-Pierre, Paul; Hirons, Budd; Kalueff, Allan V

    2012-03-01

    Zebrafish (Danio rerio) are widely used in neuroscience research, where their utility as a model organism is rapidly expanding. Low cost, ease of experimental manipulations, and sufficient behavioral complexity make zebrafish a valuable tool for high-throughput studies in biomedicine. To complement the available repositories for zebrafish genetic information, there is a growing need for the collection of zebrafish neurobehavioral and neurological phenotypes. For this, we are establishing the Zebrafish Neurophenome Database (ZND; www.tulane.edu/∼znpindex/search ) as a new dynamic online open-access data repository for behavioral and related physiological data. ZND, currently focusing on adult zebrafish, combines zebrafish neurophenotypic data with a simple, easily searchable user interface, which allow scientists to view and compare results obtained by other laboratories using various treatments in different testing paradigms. As a developing community effort, ZND is expected to foster innovative research using zebrafish by federating the growing body of zebrafish neurophenotypic data.

  12. Conformational dynamics of ligand-dependent alternating access in LeuT.

    Science.gov (United States)

    Kazmier, Kelli; Sharma, Shruti; Quick, Matthias; Islam, Shahidul M; Roux, Benoît; Weinstein, Harel; Javitch, Jonathan A; McHaourab, Hassane S

    2014-05-01

    The leucine transporter (LeuT) from Aquifex aeolicus is a bacterial homolog of neurotransmitter/sodium symporters (NSSs) that catalyze reuptake of neurotransmitters at the synapse. Crystal structures of wild-type and mutants of LeuT have been interpreted as conformational states in the coupled transport cycle. However, the mechanistic identities inferred from these structures have not been validated, and the ligand-dependent conformational equilibrium of LeuT has not been defined. Here, we used distance measurements between spin-label pairs to elucidate Na(+)- and leucine-dependent conformational changes on the intracellular and extracellular sides of the transporter. The results identify structural motifs that underlie the isomerization of LeuT between outward-facing, inward-facing and occluded states. The conformational changes reported here present a dynamic picture of the alternating-access mechanism of LeuT and NSSs that is different from the inferences reached from currently available structural models.

  13. Hamiltonian magnetohydrodynamics: Lagrangian, Eulerian, and dynamically accessible stability—Examples with translation symmetry

    Science.gov (United States)

    Andreussi, T.; Morrison, P. J.; Pegoraro, F.

    2016-10-01

    Because different constraints are imposed, stability conditions for dissipationless fluids and magnetofluids may take different forms when derived within the Lagrangian, Eulerian (energy-Casimir), or dynamically accessible frameworks. This is in particular the case when flows are present. These differences are explored explicitly by working out in detail two magnetohydrodynamic examples: convection against gravity in a stratified fluid and translationally invariant perturbations of a rotating magnetized plasma pinch. In this second example, we show in explicit form how to perform the time-dependent relabeling introduced in Andreussi et al. [Phys. Plasmas 20, 092104 (2013)] that makes it possible to reformulate Eulerian equilibria with flows as Lagrangian equilibria in the relabeled variables. The procedures detailed in the present article provide a paradigm that can be applied to more general plasma configurations and in addition extended to more general plasma descriptions where dissipation is absent.

  14. Hamiltonian Magnetohydrodynamics: Lagrangian, Eulerian, and Dynamically Accessible Stability -- Examples with Translation Symmetry

    CERN Document Server

    Andreussi, T; Pegoraro, F

    2016-01-01

    Because different constraints are imposed, stability conditions for dissipationless fluids and magnetofluids may take different forms when derived within the Lagrangian, Eulerian (energy-Casimir), or dynamical accessible frameworks. This is in particular the case when flows are present. These differences are explored explicitly by working out in detail two magnetohydrodynamic examples: convection against gravity in a stratified fluid and translationally invariant perturbations of a rotating magnetized plasma pinch. In this second example we show in explicit form how to perform the time-dependent relabeling introduced in Andreussi {\\it et al.}\\ [Phys.\\ Plasmas {\\bf20}, 092104 (2013)] that makes it possible to reformulate Eulerian equilibria with flows as Lagrangian equilibria in the relabeled variables. The procedures detailed in the present article provide a paradigm that can be applied to more general plasma configurations and in addition extended to more general plasma descriptions where dissipation is abse...

  15. A Dynamic Web Page Prediction Model Based on Access Patterns to Offer Better User Latency

    CERN Document Server

    Mukhopadhyay, Debajyoti; Saha, Dwaipayan; Kim, Young-Chon

    2011-01-01

    The growth of the World Wide Web has emphasized the need for improvement in user latency. One of the techniques that are used for improving user latency is Caching and another is Web Prefetching. Approaches that bank solely on caching offer limited performance improvement because it is difficult for caching to handle the large number of increasingly diverse files. Studies have been conducted on prefetching models based on decision trees, Markov chains, and path analysis. However, the increased uses of dynamic pages, frequent changes in site structure and user access patterns have limited the efficacy of these static techniques. In this paper, we have proposed a methodology to cluster related pages into different categories based on the access patterns. Additionally we use page ranking to build up our prediction model at the initial stages when users haven't already started sending requests. This way we have tried to overcome the problems of maintaining huge databases which is needed in case of log based techn...

  16. Reconfigurable radio access unit to dynamically distribute W-band signals in 5G wireless access networks

    DEFF Research Database (Denmark)

    Rodríguez Páez, Juan Sebastián; Rommel, Simon; Vegas Olmos, Juan José

    2017-01-01

    In this paper a new type of radio access unit is proposed and demonstrated. This unit is composed only of the reduced amount of components (compared to conventional unit designs) to optically generate wireless signals on the W-band (75–110 GHz) in combination with a switching system. The proposed...... system not only achieves BER values below the FEC limit, but gives an extra level of flexibility to the network by easing the redirection of the signal to different antennas....

  17. 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.

  18. Work in television white spaces (TVWS) and dynamic spectrum and a bit on antennas (conference presentation)

    CSIR Research Space (South Africa)

    Lysko, A

    2016-07-01

    Full Text Available ., “First Large TV White Spaces Trial in South Africa: A Brief Overview,” ICUMT 2014, Russia • Masonta, M.T.; Kola, L.M. ; Lysko, A.A. ; Pieterse, L. ; Velempini, M., “Network performance analysis of the Limpopo TV white space (TVWS) trial network,” IEEE... space networks alive Spectrum DB White Space BS radio White Space CPE radio  No contact with Spectrum DB -> all WS connected to DB shut down  Political interference (Egypt, Syria)  Natural disaster  Network failures Move to reserved survival...

  19. Review and Perspective of Architecture Development for Dynamic Random Access Memory

    Institute of Scientific and Technical Information of China (English)

    WANG Yu-xing; WU Jin

    2008-01-01

    Discussed is a review and perspective of architecture, materials and process technology for dynamic random access memory(DRAM) applications. Key challenges of the transistor and capacitor scaling from DRAM will be reviewed. To continue scaling down, multi-gate devices with very thin silicon channels are most promising. Several architectures like Fin-field effect transistor(Fin-FET), Wafer bonded double gate and silicon on nothing(SON) gate-all-around have been demonstrated with good electrical characteristics. An overview of the evolution of capacitor technology is also presented from the early days of planar poly/insulator/silicon(PIS) capacitors to the metal/insulator/metal(MIM) capacitors used for today 50 nm technology node and below. In comparing Ta2O5, HfO2 and Al2O3 as high-k dielectric for use in DRAM technology, Al2O3 is found to give a good compromise between capacitor performance and manufacturability used in MIM architecture.

  20. The Dynamics of πN Scattering and the Baryon Spectrum

    Science.gov (United States)

    Afnan, I. R.

    1998-09-01

    In the present analysis I will detail a procedure for calculating the baryon spectrum as a solution of an eigenvalue problem that generates both the mass and width of the state. This is illustrated for the case of the Δ and Roper resonances.

  1. The dynamics of {pi}N scattering and the baryon spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Afnan, I.R. [Department of Physics, Flinders University of South Australia, Adelaide (Australia)

    1998-09-01

    In the present analysis I will detail a procedure for calculating the baryon spectrum as a solution of an eigenvalue problem that generates both the mass and width of the state. This is illustrated for the case of the {Delta} and Roper resonances. (author) 7 refs, 3 figs, 1 tab

  2. GASDRA: Galaxy Spectrum Dynamic Range Analysis for Photometric Redshift Filter Partition Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Vicente, J. de; Sanchez, E.; Sevilla, I.; Castilla, J.; Ponce, R.; Sanchez, F. J.

    2012-04-11

    The photometric redshift is an active area of research. It is becoming the preferred method for redshift measurement above spectroscopy one for large surveys. In these surveys, the requirement in redshift precision is relaxed in benefit of obtaining the measurements of large number of galaxies. One of the more relevant decisions to be taken in the design of a photometric redshift experiment is the number of filters since it affects deeply to the precision and survey time. Currently, there is not a clear method for evaluating the impact in both precision and exposure time of a determined filter partition set and usually it is determined by detailed simulations on the behavior of photo-z algorithms. In this note we describe GASDRA, a new method for extracting the minimal signal to noise requirement, depending on the number of filters needed for preserving the filtered spectrum shape, and hence to make feasible the spectrum identification. The application of this requirement guaranties a determined precision in the spectrum measurement. Although it cannot be translated directly to absolute photometric redshift error, it does provide a method for comparing the relative precision achieved in the spectrum representation by different sets of filters. We foresee that this relative precision is close related to photo-z error. In addition, we can evaluate the impact in the exposure time of any filter partition set with respect to other. (Author) 11 refs.

  3. Exploring Perceptual Skills in Children with Autism Spectrum Disorders: From Target Detection to Dynamic Perceptual Discrimination

    Science.gov (United States)

    Miller, Louisa; McGonigle-Chalmers, Maggie

    2014-01-01

    Perceptual processing in autism is associated with both "strengths" and "weaknesses" but within a literature that varies widely in terms of the assessments used. We report data from 12 children with autism spectrum disorders (ASD) and 12 age and IQ matched neurotypical controls tested on a set of tasks using the same stimuli…

  4. Impact of Energetically Accessible Proton Permutations in the Spectroscopy and Dynamics of H{_5^+}

    Science.gov (United States)

    Lin, Zhou; McCoy, Anne B.

    2016-06-01

    H{_5^+} has been proposed to be the intermediate of the astrochemically interesting proton transfer reaction H_3^+ + H_2 → H_2 + H_3^+. The scrambling of five protons in this floppy, ``structureless'' ion introduces complications to its high-resolution rovibrational spectroscopy and the proton transfer dynamics between H{_3^+} and H_2. Quantum chemical studies are performed to predict and interpret the spectroscopic and dynamical properties of H{_5^+}, with special consideration paid to the group theoretical aspects. If the full permutation of protons were allowed in H{_5^+}, just like in CH{_5^+}, the system should have been characterized by the G240 complete permutation-inversion group. However, our diffusion Monte Carlo calculations indicate that such a full permutation is not allowed for most of the molecular configurations sampled by the reaction path of the proton transfer process in question, and the energetically accessible permutations are functions of the distance between the H{_3^+} and H_2 fragments. In the present study, we investigate two extreme geometries of H{_5^+}, the [H_2-H-H_2]^+ shared-proton intermediate and the H_3^+\\cdots H_2 long-range complex, using two subgroups of G240, G16 and G24, respectively. In these two limiting circumstances, we derive the symmetry-adapted basis functions for the energy levels that describe the nuclear spins and the rovibrational motions of H{_5^+}. Based on the results of these derivations, we discuss the spectroscopic properties of H{_5^+}, including the coupling between different rovibrational degrees of freedom in the effective nuclear motion Hamiltonian, the electric-dipole selection rules for rovibrational spectroscopy, and correlations of energy levels between [H_2-H-H_2]^+ and H_3^+\\cdots H_2. Our study can be considered as the first step towards the implementation of future quantitative theoretical investigations for comparison with spectroscopic and dynamical experiments. X.-G. Wang and T

  5. Photosystem II function and dynamics in three widely used Arabidopsis thaliana accessions.

    Directory of Open Access Journals (Sweden)

    Lan Yin

    Full Text Available Columbia-0 (Col-0, Wassilewskija-4 (Ws-4, and Landsberg erecta-0 (Ler-0 are used as background lines for many public Arabidopsis mutant collections, and for investigation in laboratory conditions of plant processes, including photosynthesis and response to high-intensity light (HL. The photosystem II (PSII complex is sensitive to HL and requires repair to sustain its function. PSII repair is a multistep process controlled by numerous factors, including protein phosphorylation and thylakoid membrane stacking. Here we have characterized the function and dynamics of PSII complex under growth-light and HL conditions. Ws-4 displayed 30% more thylakoid lipids per chlorophyll and 40% less chlorophyll per carotenoid than Col-0 and Ler-0. There were no large differences in thylakoid stacking, photoprotection and relative levels of photosynthetic complexes among the three accessions. An increased efficiency of PSII closure was found in Ws-4 following illumination with saturation flashes or continuous light. Phosphorylation of the PSII D1/D2 proteins was reduced by 50% in Ws-4 as compared to Col-0 and Ler-0. An increase in abundance of the responsible STN8 kinase in response to HL treatment was found in all three accessions, but Ws-4 displayed 50% lower levels than Col-0 and Ler-0. Despite this, the HL treatment caused in Ws-4 the lagest extent of PSII inactivation, disassembly, D1 protein degradation, and the largest decrease in the size of stacked thylakoids. The dilution of chlorophyll-protein complexes with additional lipids and carotenoids in Ws-4 may represent a mechanism to facilitate lateral protein traffic in the membrane, thus compensating for the lack of a full complement of STN8 kinase. Nevertheless, additional PSII damage occurs in Ws-4, which exceeds the D1 protein synthesis capacity, thus leading to enhanced photoinhibition. Our findings are valuable for selection of appropriate background line for PSII characterization in Arabidopsis

  6. Modern Dynamical Coupled-Channels Calculations for Extracting and Understanding the Nucleon Spectrum

    CERN Document Server

    Kamano, Hiroyuki

    2016-01-01

    We give an overview of recent progress in the spectroscopic study of nucleon resonances within the dynamical coupled-channels analysis of meson-production reactions. The important role of multichannel reaction dynamics in understanding various properties of nucleon resonances is emphasized.

  7. Full dimensional (15-dimensional) quantum-dynamical simulation of the protonated water dimer. II. Infrared spectrum and vibrational dynamics

    DEFF Research Database (Denmark)

    Vendrell, Oriol; Gatti, Fabien; Meyer, Hans-Dieter

    2007-01-01

    the fundamentals and several overtones of the vibrational motion are computed. The spectrum of H5O2+ is shaped to a large extent by couplings of the proton-transfer motion to large amplitude fluxional motions of the water molecules, water bending and water-water stretch motions. These couplings are identified...... and discussed, and the corresponding spectral lines are assigned. The large couplings featured by H5O2+ do not hinder, however, to describe the coupled vibrational motion by well defined simple types of vibration (stretching, bending; etc.) based on well defined modes of vibration, in terms of which...

  8. A polarimetric approach for constraining the dynamic foreground spectrum for cosmological global 21-cm measurements

    CERN Document Server

    Nhan, Bang D; Burns, Jack O

    2016-01-01

    The cosmological global (sky-averaged) 21-cm signal is a powerful tool to probe the evolution of the intergalactic medium (IGM) in high-redshift Universe ($z \\leq 6$). One of the biggest observational challenges is to remove the foreground spectrum which is at least four orders of magnitude brighter than the cosmological 21-cm emission. Conventional global 21-cm experiments rely on the spectral smoothness of the foreground synchrotron emission to separate it from the unique 21-cm spectral structures in a single total-power spectrum. However, frequency-dependent instrumental and observational effects are known to corrupt such smoothness and complicates the foreground subtraction. We introduce a polarimetric approach to measure the projection-induced polarization of the anisotropic foreground onto a stationary dual-polarized antenna. Due to Earth rotation, when pointing the antenna at a celestial pole, the revolving foreground will modulate this polarization with a unique frequency-dependent sinusoidal signatur...

  9. Relaxation of the entanglement spectrum in quench dynamics of topological systems

    Science.gov (United States)

    Jhu, Yi-Hao; Chen, Pochung; Chung, Ming-Chiang

    2017-07-01

    In this paper, we investigate how the entanglement spectrum relaxes to its steady-state values in one-dimensional quadratic systems after a quantum quench. In particular, we apply saddle-point expansion to dimerized chains and 1D p-wave superconductors. We found the entanglement spectrum to always exhibit a power-law relaxation superimposed with oscillations at certain characteristic angular frequencies. For dimerized chains, we found the exponent ν of the power-law decay to always be 3/2 . For 1D p-wave superconductors, however, we found that, depending on the initial and final Hamiltonian, the exponent ν can take its value from a limited list of values, the smallest possible of which is ν=1/2 , which leads to a very slow convergence to its steady-state value.

  10. Index of Access: a new innovative and dynamic tool for rural health service and workforce planning.

    Science.gov (United States)

    McGrail, Matthew R; Russell, Deborah J; Humphreys, John S

    2016-08-19

    Objective Improving access to primary health care (PHC) remains a key issue for rural residents and health service planners. This study aims to show that how access to PHC services is measured has important implications for rural health service and workforce planning.Methods A more sophisticated tool to measure access to PHC services is proposed, which can help health service planners overcome the shortcomings of existing measures and long-standing access barriers to PHC. Critically, the proposed Index of Access captures key components of access and uses a floating catchment approach to better define service areas and population accessibility levels. Moreover, as demonstrated through a case study, the Index of Access enables modelling of the effects of workforce supply variations.Results Hypothetical increases in supply are modelled for a range of regional centres, medium and small rural towns, with resulting changes of access scores valuable to informing health service and workforce planning decisions.Conclusions The availability and application of a specific 'fit-for-purpose' access measure enables a more accurate empirical basis for service planning and allocation of health resources. This measure has great potential for improved identification of PHC access inequities and guiding redistribution of PHC services to correct such inequities.What is known about the topic? Resource allocation and health service planning decisions for rural and remote health settings are currently based on either simple measures of access (e.g. provider-to-population ratios) or proxy measures of access (e.g. standard geographical classifications). Both approaches have substantial limitations for informing rural health service planning and decision making.What does this paper add? The adoption of a new improved tool to measure access to PHC services, the Index of Access, is proposed to assist health service and workforce planning. Its usefulness for health service planning is

  11. [Passive SLF spectrum analysis for tracing the mining dynamic of CBM].

    Science.gov (United States)

    Jiang, Hong-bo; Qin, Qi-ming; Li, Bai-shou

    2011-07-01

    Exploration and development of the coal-bed methane (CBM) is very important to economics, environment and society. It is a key factor to trace and assess the process of the coal-bed gas mining dynamically for its efficient development. In the present article, based on the theory of natural resources super low frequency (SLF) electromagnetic detecting, the method that uses the SLF to trace the coal-bed gas mining dynamic is introduced. The field tests in 2007 and 2010 in the Qin-Shui basin, Shanxi province of China indicate that this method is efficient for the dynamic of the coal-bed gas mining.

  12. Dirac equation, hydrogen atom spectrum and the Lamb shift in dynamical non-commutative spaces

    Indian Academy of Sciences (India)

    S A ALAVI; N REZAEI

    2017-05-01

    We derive the relativistic Hamiltonian of hydrogen atom in dynamical non-commutative spaces (DNCS or $\\tau$ -space). Using this Hamiltonian we calculate the energy shift of the ground state as well the $2P_{1/2}$, $2S_{1/2}$levels. In all the cases, the energy shift depends on the dynamical non-commutative parameter $\\tau$. Using the accuracy of the energy measurement, we obtain an upper bound for $\\tau$. We also study the Lamb shift in DNCS. Both $2P_{1/2}$ and $2S_{1/2}$ levels receive corrections due to dynamical non-commutativity of space which is in contrast with the non-dynamical non-commutative spaces (NDNCS or $\\theta$-space) in which the $2S_{1/2}$ level receives no correction.

  13. Low lying baryon spectrum with N{sub f}=2+1+1 dynamical twisted quarks

    Energy Technology Data Exchange (ETDEWEB)

    Drach, Vincent; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Carbonell, Jaume; Papinutto, Mauro [UJF, CNRS/IN2P3, INPG (France). Lab. de Physique Subatomique et de Cosmologie; Alexandrou, Constantia [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics

    2010-12-15

    We present first results on the octet and decuplet strange baryon spectrum with N{sub f}=2+1+1 twisted mass quarks. We use an Osterwalder Seiler valence strange quark with a mass tuned to the kaon and compare the results with those obtained in the unitary setup. This comparison allows to perform a first study of the lattice artefacts introduced by the mixed action approach. We investigate the effect of the strange and charm quarks in the sea by using two lattice spacings and comparing with preceding N{sub f}=2 twisted mass fermion calculations. (orig.)

  14. Work in Television White Spaces (TVWS) and Dynamic Spectrum and a bit on Antennas

    CSIR Research Space (South Africa)

    Lysko, AA

    2016-07-01

    Full Text Available and trials of television white space (TVWS) technology. The TVWS refers to the reuse of ultra-high frequency (UHF) portion of TV broadcasting spectrum to provide wireless communications without causing interference to reception of TV. The reason... stream_source_info Lysko_2016.pdf.txt stream_content_type text/plain stream_size 3636 Content-Encoding UTF-8 stream_name Lysko_2016.pdf.txt Content-Type text/plain; charset=UTF-8 Work in Television White Spaces (TVWS...

  15. Low lying baryon spectrum with $N_f = 2+1+1$ dynamical twisted quarks

    CERN Document Server

    Drach, Vincent; Carbonell, Jaume; Papinutto, Mauro; Alexandrou, Constantia

    2010-01-01

    We present first results on the octet and decuplet strange baryon spectrum with $N_f=2+1+1$ twisted mass quarks. We use an Osterwalder Seiler valence strange quark with a mass tuned to the kaon and compare the results with those obtained in the unitary setup. This comparison allows to perform a first study of the lattice artefacts introduced by the mixed action approach. We investigate the effect of the strange and charm quarks in the sea by using two lattice spacings and comparing with preceding $N_f = 2$ twisted mass fermion calculations.

  16. 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...

  17. On Green Cognitive Radio Cellular Networks: Dynamic Spectrum and Operation Management

    KAUST Repository

    Sboui, Lokman

    2016-07-18

    We study a profit maximization problem related to cognitive radio cellular networks in an environmentally- friendly framework. The objective of the primary network (PN) and secondary network (SN) is to maximize their profits while respecting a certain carbon dioxide (CO2) emissions threshold. In this study, the PN can switch off some of its base stations (BSs) powered by mircogrids, and hence leases the spectrum in the corresponding cells, to reduce its footprint. The corresponding users are roamed to the SN infrastructure. In return, the SN receives a certain roaming cost and its users can freely exploit the spectrum. We study two scenarios in which the profits are either separately or jointly maximized. In the disjoint maximization problem, two low complexity algorithms for PN and SN BS on/off switching are proposed to maximize the profit per CO2 emissions utility and determine the amount of the shared bandwidth. In the joint maximization approach, the low complexity algorithm is based on maximizing the sum of weighted profits per CO2. Selected numerical results illustrate the collaboration performance versus various system parameters. We show that the proposed algorithms achieve performances close to those obtained with the exhaustive search method, and that the roaming price and the renewable energy availability are crucial parameters that control the collaboration of both networks.

  18. Dynamic localization and Bloch oscillations in the spectrum of a frequency mode-locked laser.

    Science.gov (United States)

    Longhi, Stefano

    2005-04-01

    It is shown that a frequency mode-locked laser with a sinusoidal sweep of modulation frequency around a mode-locking condition represents an ideal optical system for observing in the spectral domain the phenomena of dynamic localization and Bloch oscillations of electrons in an ideal solid placed in an external ac electric field.

  19. Proglacial hydrochemistry and sediment characteristics observed across a spectrum of glacier dynamic regimes

    Science.gov (United States)

    Crompton, J. W.; Flowers, G. E.

    2015-12-01

    The broad influence of bedrock geology on glacier dynamics has received comparatively little attention in the alpine glacier literature. Geological influences vary widely from subglacial hydrochemistry to deformable till rheology, which may be governed by the mineralogy and grain size distribution within the till. In an investigation of borehole and proglacial water at an unnamed glacier in the Donjek Range of the St. Elias Mountains, Yukon, Canada, we find that subglacial mineral precipitation exerts a significant control on the proglacial hydrochemistry and suspended sediment flux. To understand if this process is common to glaciers across the range, we collected proglacial water samples from 20 glaciers in and around the Donjek Range. From each sample, we analyzed the hydrochemistry, measured the grain size distribution (GSD) using a Mastersizer laser diffraction particle size analyzer, and analyzed the mineralogy of the suspended sediments using X-ray diffraction. We also analyzed thin sections from bedrock samples collected at the glacier margins to constrain the mineralogical input to the system. This suite of measurements permits us to investigate the discrepancies between the secondary minerals predicted by the proglacial hydrochemistry and the observed mineralogy. Given that glaciers in the sample set exhibit a range of dynamic behaviour (including surging), we investigate how the mineralogy, GSDs, and hydrochemistry vary as a function of glacier dynamics. Where we have identified correlations between surging glaciers and proglacial GSDs, we investigate the possible controls of hydrochemistry and/or mineralogy on the GSDs and thus on subglacial dynamics.

  20. On the modeling and nonlinear dynamics of autonomous Silva-Young type chaotic oscillators with flat power spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Kengne, Jacques [Laboratoire d' Automatique et Informatique Apliquée (LAIA), Department of Electrical Engineering, IUT-FV Bandjoun, University of Dschang, Bandjoun (Cameroon); Kenmogne, Fabien [Laboratory of Modeling and Simulation in Engineering, Biomimetics and Prototype, University of Yaoundé 1, Yaoundé (Cameroon)

    2014-12-15

    The nonlinear dynamics of fourth-order Silva-Young type chaotic oscillators with flat power spectrum recently introduced by Tamaseviciute and collaborators is considered. In this type of oscillators, a pair of semiconductor diodes in an anti-parallel connection acts as the nonlinear component necessary for generating chaotic oscillations. Based on the Shockley diode equation and an appropriate selection of the state variables, a smooth mathematical model (involving hyperbolic sine and cosine functions) is derived for a better description of both the regular and chaotic dynamics of the system. The complex behavior of the oscillator is characterized in terms of its parameters by using time series, bifurcation diagrams, Lyapunov exponents' plots, Poincaré sections, and frequency spectra. It is shown that the onset of chaos is achieved via the classical period-doubling and symmetry restoring crisis scenarios. Some PSPICE simulations of the nonlinear dynamics of the oscillator are presented in order to confirm the ability of the proposed mathematical model to accurately describe/predict both the regular and chaotic behaviors of the oscillator.

  1. Modelling of hydrogen thermal desorption spectrum in nonlinear dynamical boundary-value problem

    Science.gov (United States)

    Kostikova, E. K.; Zaika, Yu V.

    2016-11-01

    One of the technological challenges for hydrogen materials science (including the ITER project) is the currently active search for structural materials with various potential applications that will have predetermined limits of hydrogen permeability. One of the experimental methods is thermal desorption spectrometry (TDS). A hydrogen-saturated sample is degassed under vacuum and monotone heating. The desorption flux is measured by mass spectrometer to determine the character of interactions of hydrogen isotopes with the solid. We are interested in such transfer parameters as the coefficients of diffusion, dissolution, desorption. The paper presents a distributed boundary-value problem of thermal desorption and a numerical method for TDS spectrum simulation, where only integration of a nonlinear system of low order (compared with, e.g., the method of lines) ordinary differential equations (ODE) is required. This work is supported by the Russian Foundation for Basic Research (project 15-01-00744).

  2. Cognitive Access to TVWS in India

    DEFF Research Database (Denmark)

    Patil, Kishor P.; Skouby, Knud Erik; Prasad, Ramjee

    2013-01-01

    The digital transition of TV transmission will make available some TV frequencies which are to be geographically unused called as TV White Spaces. The important regulatory trend in the context of Dynamic Spectrum Access (DSA) is the Cognitive access of TV white Spaces. In this context, we have pe...... of India, we have proposed wireless broadband access to rural areas using TV White Spaces (TVWSs). This will help in bridging the digital divide by offering governance, banking, and health services online in the rural areas.......The digital transition of TV transmission will make available some TV frequencies which are to be geographically unused called as TV White Spaces. The important regulatory trend in the context of Dynamic Spectrum Access (DSA) is the Cognitive access of TV white Spaces. In this context, we have...... performed spectrum measurements of TV band in Pune, India. Our result shows poor spectrum utilization in TV band, and good potential for Cognitive radio operation. Digital switchover in India will generate golden opportunity for empowering rural India. As majority of India’s population lives in rural part...

  3. Wavelength selection based on two-dimensional correlation spectroscopy: application to noninvasive hemoglobin measurement by dynamic spectrum

    Science.gov (United States)

    Zhang, Shengzhao; Zhang, Linna; Li, Zhe; Li, Gang; Lin, Ling

    2016-10-01

    Dynamic spectrum (DS) method is one of the noninvasive approaches to measure the concentration of components in human blood based on the application of photoplethysmogram (PPG). One of the targets of the DS method is to predict the hemoglobin concentration in human blood noninvasively. In previous works, the usually used wavelength in the spectrum is 600-1100 nm which is regarded as the analysis "window" in human tissues. Optimum wavelengths for measurements of hemoglobin concentration have not been investigated yet. In order to improve the precision and reliability of hemoglobin measurements, a method for wavelength selection based on two-dimension (2D) correlation spectroscopy has been studied in this paper. By analyzing the 2D correlation spectroscopy which is generated by the DS data from subject with different blood hemoglobin concentrations, the wavelength bands which are sensible to hemoglobin concentrations in DS can be found. We developed calibration models between the DS data and hemoglobin concentration based on data from 57 subjects. The correlation coefficient is 0.68 in the test set of the model using the whole wavelength band (600-1100nm), while in the test set of the model using the selected wavelength band (850- 950nm) the correlation coefficient is 0.87. Results show the feasibility of wavelength selection utilizing 2Dcorrelation spectroscopy.

  4. Implementation of an Optical-Wireless Network with Spectrum Sensing and Dynamic Resource Allocation Using Optically Controlled Reconfigurable Antennas

    Directory of Open Access Journals (Sweden)

    E. Raimundo-Neto

    2014-01-01

    Full Text Available This work proposes the concept and reports the implementation of an adaptive and cognitive radio over fiber architecture. It is aimed at dealing with the new demands for convergent networks by means of simultaneously providing the functionalities of multiband radiofrequency spectrum sensing, dynamic resource allocation, and centralized processing capability, as well as the use of optically controlled reconfigurable antennas and radio over fiber technology. The performance of this novel and innovative architecture has been evaluated in a geographically distributed optical-wireless network under real conditions and for different fiber lengths. Experimental results demonstrate reach extension of more than 40 times and an enhancement of more than 30 dB in the carrier to interference plus noise ratio parameter.

  5. Elucidating the Ultrafast Dynamics of Photoinduced Charge Separation in Metalloporphyrin-Fullerene Dyads Across the Electromagnetic Spectrum

    DEFF Research Database (Denmark)

    Zhang, J.; Pápai, Mátyás Imre; Hirsch, A.

    2016-01-01

    Metalloporphyrins are prominent building blocks in the synthetic toolbox of advanced photodriven molecular devices. When the central ion is paramagnetic, the relaxation pathways within the manifold of excited states are highly intricate so that unravelling the intramolecular energy and electron...... transfer processes is usually a very complex task. This fact is critically hampering the development of applications based on the enhanced coupling offered by the electronic exchange interaction. In this work, the dynamics of charge separation in a copper porphyrin-fullerene are studied with several...... complementary spectroscopic tools across the electromagnetic spectrum (from near-infrared to X-ray wavelengths), each of them providing specific diagnostics. Correlating the various rates clearly demonstrates that the lifetime of the photoinduced charge-separated state exceeds by about 10-fold...

  6. A novel microwave absorption and dielectric spectrum detection technology in photoelectron dynamic study for solar cells

    Institute of Scientific and Technical Information of China (English)

    LI Xiaowei; SUN Shuxu; LAI Weidong; ZHANG Rongxiang; DAI Xiuhong; JIANG Xiaoli

    2006-01-01

    The photoelectron property is directly related to the light-energy conversion efficiency of solar cells. In this paper, the photoelectron dynamic of semiconductor was analyzed. The diffusion of electrons has influence on the dielectric function of the solar cell material. And the amplitude variance of the imaginary andreal part of the dielectric function is in direct proportion to the dynamic process of free and shallow-trapped electrons. Based on the untouched detection technique, the method is present to detect the amplitude change of the microwave signal which is passing through the material whose dielectric function changes after exposure. A35GHz oscillator was used as a microwave source. The absorptionand dispersion microwave signals, which contain the dynamic information of free and shallow-trapped electron signal, are split respectively with phase-sensitive instrument. The photoelectron character of n-type Si(100) thin film was investigated by the novel equipment, and the lifetime of different kinds of electronswith the resolution of 1 ns was obtained. The equipment can be directly used inthe study of the optoelectronic conversion mechanism of solar cells.

  7. Assessing blood brain barrier dynamics or identifying or measuring selected substances or toxins in a subject by analyzing Raman spectrum signals of selected regions in the eye

    Science.gov (United States)

    Lambert, James L. (Inventor); Borchert, Mark S. (Inventor)

    2003-01-01

    A non-invasive method for analyzing the blood-brain barrier includes obtaining a Raman spectrum of a selected portion of the eye and monitoring the Raman spectrum to ascertain a change to the dynamics of the blood brain barrier. Also, non-invasive methods for determining the brain or blood level of an analyte of interest, such as glucose, drugs, alcohol, poisons, and the like, comprises: generating an excitation laser beam (e.g., at a wavelength of 600 to 900 nanometers); focusing the excitation laser beam into the anterior chamber of an eye of the subject so that aqueous humor, vitreous humor, or one or more conjunctiva vessels in the eye is illuminated; detecting (preferably confocally detecting) a Raman spectrum from the illuminated portion of the eye; and then determining the blood level or brain level (intracranial or cerebral spinal fluid level) of an analyte of interest for the subject from the Raman spectrum. In certain embodiments, the detecting step may be followed by the step of subtracting a confounding fluorescence spectrum from the Raman spectrum to produce a difference spectrum; and determining the blood level and/or brain level of the analyte of interest for the subject from that difference spectrum, preferably using linear or nonlinear multivariate analysis such as partial least squares analysis. Apparatus for carrying out the foregoing methods are also disclosed.

  8. Assessing blood brain barrier dynamics or identifying or measuring selected substances, including ethanol or toxins, in a subject by analyzing Raman spectrum signals

    Science.gov (United States)

    Lambert, James L. (Inventor); Borchert, Mark S. (Inventor)

    2008-01-01

    A non-invasive method for analyzing the blood-brain barrier includes obtaining a Raman spectrum of a selected portion of the eye and monitoring the Raman spectrum to ascertain a change to the dynamics of the blood brain barrier.Also, non-invasive methods for determining the brain or blood level of an analyte of interest, such as glucose, drugs, alcohol, poisons, and the like, comprises: generating an excitation laser beam at a selected wavelength (e.g., at a wavelength of about 400 to 900 nanometers); focusing the excitation laser beam into the anterior chamber of an eye of the subject so that aqueous humor, vitreous humor, or one or more conjunctiva vessels in the eye is illuminated; detecting (preferably confocally detecting) a Raman spectrum from the illuminated portion of the eye; and then determining the blood level or brain level (intracranial or cerebral spinal fluid level) of an analyte of interest for the subject from the Raman spectrum. In certain embodiments, the detecting step may be followed by the step of subtracting a confounding fluorescence spectrum from the Raman spectrum to produce a difference spectrum; and determining the blood level and/or brain level of the analyte of interest for the subject from that difference spectrum, preferably using linear or nonlinear multivariate analysis such as partial least squares analysis. Apparatus for carrying out the foregoing methods are also disclosed.

  9. Altered Onset Response Dynamics in Somatosensory Processing in Autism Spectrum Disorder.

    Science.gov (United States)

    Khan, Sheraz; Hashmi, Javeria A; Mamashli, Fahimeh; Bharadwaj, Hari M; Ganesan, Santosh; Michmizos, Konstantinos P; Kitzbichler, Manfred G; Zetino, Manuel; Garel, Keri-Lee A; Hämäläinen, Matti S; Kenet, Tal

    2016-01-01

    Abnormalities in cortical connectivity and evoked responses have been extensively documented in autism spectrum disorder (ASD). However, specific signatures of these cortical abnormalities remain elusive, with data pointing toward abnormal patterns of both increased and reduced response amplitudes and functional connectivity. We have previously proposed, using magnetoencephalography (MEG) data, that apparent inconsistencies in prior studies could be reconciled if functional connectivity in ASD was reduced in the feedback (top-down) direction, but increased in the feedforward (bottom-up) direction. Here, we continue this line of investigation by assessing abnormalities restricted to the onset, feedforward inputs driven, component of the response to vibrotactile stimuli in somatosensory cortex in ASD. Using a novel method that measures the spatio-temporal divergence of cortical activation, we found that relative to typically developing participants, the ASD group was characterized by an increase in the initial onset component of the cortical response, and a faster spread of local activity. Given the early time window, the results could be interpreted as increased thalamocortical feedforward connectivity in ASD, and offer a plausible mechanism for the previously observed increased response variability in ASD, as well as for the commonly observed behaviorally measured tactile processing abnormalities associated with the disorder.

  10. Dynamic Akt/mTOR Signaling in Children with Autism Spectrum Disorder

    Science.gov (United States)

    Onore, Charity; Yang, Houa; Van de Water, Judy; Ashwood, Paul

    2017-01-01

    Autism spectrum disorder (ASD) is a behaviorally defined disorder affecting 1 in 68 children. Currently, there is no known cause for the majority of ASD cases nor are there physiological diagnostic tools or biomarkers to aid behavioral diagnosis. Whole-genome linkage studies, genome-wide association studies, copy number variation screening, and SNP analyses have identified several ASD candidate genes, but which vary greatly among individuals and family clusters, suggesting that a variety of genetic mutations may result in a common pathology or alter a common mechanistic pathway. The Akt/mammalian target of rapamycin (mTOR) pathway is involved in many cellular processes including synaptic plasticity and immune function that can alter neurodevelopment. In this study, we examined the activity of the Akt/mTOR pathway in cells isolated from children with ASD and typically developing controls. We observed higher activity of mTOR, extracellular receptor kinase, and p70S6 kinase and lower activity of glycogen synthase kinase 3 (GSK3)α and tuberin (TSC2) in cells from children with ASD. These data suggest a phosphorylation pattern indicative of higher activity in the Akt/mTOR pathway in children with general/idiopathic ASD and may suggest a common pathological pathway of interest for ASD.

  11. Computing the Lyapunov spectrum of a dynamical system from an observed time series

    Science.gov (United States)

    Brown, Reggie; Bryant, Paul; Abarbanel, Henry D. I.

    1991-01-01

    The paper examines the problem of accurately determining, from an observed time series, the Liapunov exponents for the dynamical system generating the data. It is shown that, even with very large data sets, it is clearly advantageous to utilize local neighborhood-to-neighborhood mappings with higher-order Taylor series rather than just local linear maps. This procedure is demonstrated on the Henon and Ikeda maps of the plane itself, the Lorenz system of three ordinary differential equations, and the Mackey-Glass delay differential equation.

  12. Computing the Lyapunov spectrum of a dynamical system from an observed time series

    Science.gov (United States)

    Brown, Reggie; Bryant, Paul; Abarbanel, Henry D. I.

    1991-01-01

    The paper examines the problem of accurately determining, from an observed time series, the Liapunov exponents for the dynamical system generating the data. It is shown that, even with very large data sets, it is clearly advantageous to utilize local neighborhood-to-neighborhood mappings with higher-order Taylor series rather than just local linear maps. This procedure is demonstrated on the Henon and Ikeda maps of the plane itself, the Lorenz system of three ordinary differential equations, and the Mackey-Glass delay differential equation.

  13. Multiantenna spectrum sensing for cognitive radio: overcoming noise uncertainty

    OpenAIRE

    López Valcarce, Roberto; Vázquez Vilar, Gonzalo; Sala Álvarez, José

    2010-01-01

    Spectrum sensing is a key ingredient of the dynamic spectrum access paradigm, but it needs powerful detectors operating at SNRs well below the decodability levels of primary signals. Noise uncertainty poses a significant challenge to the development of such schemes, requiring some degree of diversity (spatial, temporal, or in distribution) for identifiability of the noise level. Multiantenna detectors exploit spatial independence of receiver thermal noise. We review this ...

  14. Design of Intelligent Cross-Layer Routing Protocols for Airborne Wireless Networks Under Dynamic Spectrum Access Paradigm

    Science.gov (United States)

    2011-05-01

    routing protocols require link layer detection and hello message to maintain multiple routes . Various single and multipath protocols , like AODV ... protocols (e.g., AODV , DSR, Optimized Link State Routing (OLSR) etc.) with and without link layer detection. The protocols with link layer detection...Reactive protocols like AODV tend to reduce the control traffic messages overhead at the cost of increased latency in finding new routes . AODV has a

  15. Spectrum Sharing between Cooperative Relay and Ad-hoc Networks: Dynamic Transmissions under Computation and Signaling Limitations

    CERN Document Server

    Sun, Yin; Li, Yunzhou; Zhou, Shidong; Xu, Xibin

    2010-01-01

    This paper studies a spectrum sharing scenario between an uplink cognitive relay network (CRN) and some nearby low power ad-hoc networks. In particular, the dynamic resource allocation of the CRN is analyzed, which aims to minimize the average interfering time with the ad-hoc networks subject to a minimal average uplink throughput constraint. A long term average rate formula is considered, which is achieved by a half-duplex decode-and-forward (DF) relay strategy with multi-channel transmissions. Both the source and relay are allowed to queue their data, by which they can adjust the transmission rates flexibly based on sensing and predicting the channel state and ad-hoc traffic. The dynamic resource allocation of the CRN is formulated as a non-convex stochastic optimization problem. By carefully analyzing the optimal transmission time scheduling, it is reduced to a stochastic convex optimization problem and solved by the dual optimization method. The signaling and computation processes are designed carefully t...

  16. Experimental grid access for dynamic discovery and data transfer in distributed interactive simulation systems

    NARCIS (Netherlands)

    A. Tirado-Ramos; K. Zajac; Z. Zhao; P.M.A. Sloot; G.D. van Albada; M. Bubak

    2003-01-01

    Interactive Problem Solving Environments (PSEs) offer an integrated approach for constructing and running complex systems, such as distributed simulation systems. New distributed infrastructures, like the Grid, support the access to a large variety of core services and resources that can be used by

  17. Policy Based Access Control in Dynamic Grid-based Collaborative Environment

    NARCIS (Netherlands)

    Y. Demchenko; L. Gommans; A. Tokmakoff; R. van Buuren

    2006-01-01

    This paper describes the design and development of a flexible, customer-driven, security infrastructure for Gridbased Collaborative Environments. The paper proposes further development of the access control model built around a service or resource provisioning agreement (e.g., an experiment or proje

  18. Dynamic micromagnetic simulation of the magnetic spectrum of permalloy nanodot array with vortex state

    Science.gov (United States)

    Peng, Y.; Zhao, G. P.; Morvan, F. J.; Wu, S. Q.; Yue, M.

    2017-01-01

    Due to its potential applications in high-density magnetic storage and spin electronic devices, the ferromagnetic resonance absorption phenomenon has recently drawn much attention. By studying the influence of different materials with various shapes on this phenomenon, the new understandings gained could lead to other applications in the future. In this paper, dynamic magnetic susceptibilities of the vortex state in permalloy nanodot arrays have been investigated using a three-dimensional object oriented micromagnetic framework (OOMMF) code with a two-dimensional periodic boundary condition (2D-PBC) extension and compared with those of a single dot carefully. The resonance mode is excited in the vortex state of nanodot arrays by the microwave magnetic field perpendicular to the dot plane. In this case only radially symmetric spin wave modes can be excited. The influence of the geometric parameters on the resonance frequency has been studied systemically, including the dot radius, the number of repeating elements, and the dot distance. One can see that the resonance peak of the dot array is higher than that of a single dot because of the induced stronger magnetostatic coupling. A critical dot distance exists at which the dot array may be treated as a single dot. There is only one resonance peak for both the dot array and the single dot, as the radius changes.

  19. Finite volume spectrum of 2D field theories from Hirota dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Gromov, Nikolay [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik]|[St. Petersburg INP, Gatchina (Russian Federation); Kazakov, Vladimir [Univ. Paris-IV, Paris (France). Ecole Normale Superieure, Lab. de Physique Theorique; Vieira, Pedro [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Potsdam (Germany)]|[Univ. do Porto (Portugal). Dept. de Fisica e Centro de Fisica do Porto Faculdade de Ciencias

    2008-12-15

    We propose, using the example of the O(4) sigma model, a general method for solving integrable two dimensional relativistic sigma models in a finite size periodic box. Our starting point is the so-called Y-system, which is equivalent to the thermodynamic Bethe ansatz equations of Yang and Yang. It is derived from the Zamolodchikov scattering theory in the cross channel, for virtual particles along the non-compact direction of the space-time cylinder. The method is based on the integrable Hirota dynamics that follows from the Y-system. The outcome is a nonlinear integral equation for a single complex function, valid for an arbitrary quantum state and accompanied by the finite size analogue of Bethe equations. It is close in spirit to the Destri-deVega (DdV) equation. We present the numerical data for the energy of various states as a function of the size, and derive the general Luescher-type formulas for the finite size corrections. We also re-derive by our method the DdV equation for the SU(2) chiral Gross-Neveu model. (orig.)

  20. Stem cell research funding policies and dynamic innovation: a survey of open access and commercialization requirements.

    Science.gov (United States)

    Lévesque, Maroussia; Kim, Jihyun Rosel; Isasi, Rosario; Knoppers, Bartha Maria; Plomer, Aurora; Joly, Yann

    2014-08-01

    This article compares and contrasts the pressures of both open access data sharing and commercialization policies in the context of publicly funded embryonic stem cell research (SCR). First, normative guidelines of international SCR organizations were examined. We then examined SCR funding guidelines and the project evaluation criteria of major funding organizations in the EU, the United Kingdom (UK), Spain, Canada and the United States. Our survey of policies revealed subtle pressures to commercialize research that include: increased funding availability for commercialization opportunities, assistance for obtaining intellectual property rights (IPRs) and legislation mandating commercialization. In lieu of open access models, funders are increasingly opting for limited sharing models or "protected commons" models that make the research available to researchers within the same region or those receiving the same funding. Meanwhile, there still is need for funding agencies to clarify and standardize terms such as "non-profit organizations" and "for-profit research," as more universities are pursuing for-profit or commercial opportunities.

  1. First measurements of D(α) spectrum produced by anisotropic fast ions in the gas dynamic trap.

    Science.gov (United States)

    Lizunov, A; Anikeev, A

    2014-11-01

    Angled injection of eight deuterium beams in gas dynamic trap (GDT) plasmas builds up the population of fast ions with the distribution function, which conserves a high degree of initial anisotropy in space, energy, and pitch angle. Unlike the Maxwellian distribution case, the fast ion plasma component in GDT cannot be exhaustively characterized by the temperature and density. The instrumentation complex to study of fast ions is comprised of motional Stark effect diagnostic, analyzers of charge exchange atoms, and others. The set of numerical codes using for equilibrium modeling is also an important tool of analysis. In the recent campaign of summer 2014, we recorded first signals from the new fast ion D-alpha diagnostic on GDT. This paper presents the diagnostic description and results of pilot measurements. The diagnostic has four lines of sight, distributed across the radius of an axially symmetric plasma column in GDT. In the present setup, a line-integrated optical signal is measured in each channel. In the transverse direction, the spatial resolution is 18 mm. Collected light comes to the grating spectrometer with the low-noise detector based on a charge-coupled device matrix. In the regime of four spectra stacked vertically on the sensor, the effective spectral resolution of measurements is approximately 0.015 nm. Exposure timing is provided by the fast optical ferroelectric crystal shutter, allowing frames of duration down to 70 μs. This number represents the time resolution of measurements. A large dynamic range of the camera permits for a measurement of relatively small light signals produced by fast ions on top of the bright background emission from the bulk plasma. The fast ion emission has a non-Gaussian spectrum featuring the characteristic width of approximately 4 nm, which can be separated from relatively narrow Gaussian lines of D-alpha and H-alpha coming from the plasma periphery, and diagnostic beam emission. The signal to noise ratio varies

  2. First measurements of D{sub α} spectrum produced by anisotropic fast ions in the gas dynamic trap

    Energy Technology Data Exchange (ETDEWEB)

    Lizunov, A.; Anikeev, A. [Budker Institute of Nuclear Physics, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation)

    2014-11-15

    Angled injection of eight deuterium beams in gas dynamic trap (GDT) plasmas builds up the population of fast ions with the distribution function, which conserves a high degree of initial anisotropy in space, energy, and pitch angle. Unlike the Maxwellian distribution case, the fast ion plasma component in GDT cannot be exhaustively characterized by the temperature and density. The instrumentation complex to study of fast ions is comprised of motional Stark effect diagnostic, analyzers of charge exchange atoms, and others. The set of numerical codes using for equilibrium modeling is also an important tool of analysis. In the recent campaign of summer 2014, we recorded first signals from the new fast ion D-alpha diagnostic on GDT. This paper presents the diagnostic description and results of pilot measurements. The diagnostic has four lines of sight, distributed across the radius of an axially symmetric plasma column in GDT. In the present setup, a line-integrated optical signal is measured in each channel. In the transverse direction, the spatial resolution is 18 mm. Collected light comes to the grating spectrometer with the low-noise detector based on a charge-coupled device matrix. In the regime of four spectra stacked vertically on the sensor, the effective spectral resolution of measurements is approximately 0.015 nm. Exposure timing is provided by the fast optical ferroelectric crystal shutter, allowing frames of duration down to 70 μs. This number represents the time resolution of measurements. A large dynamic range of the camera permits for a measurement of relatively small light signals produced by fast ions on top of the bright background emission from the bulk plasma. The fast ion emission has a non-Gaussian spectrum featuring the characteristic width of approximately 4 nm, which can be separated from relatively narrow Gaussian lines of D-alpha and H-alpha coming from the plasma periphery, and diagnostic beam emission. The signal to noise ratio varies

  3. Seeing with the nano-eye: accessing structure, function, and dynamics of matter on its natural length and time scales

    Science.gov (United States)

    Raschke, Markus

    2015-03-01

    To understand and ultimately control the properties of most functional materials, from molecular soft-matter to quantum materials, requires access to the structure, coupling, and dynamics on the elementary time and length scales that define the microscopic interactions in these materials. To gain the desired nanometer spatial resolution with simultaneous spectroscopic specificity we combine scanning probe microscopy with different optical, including coherent, nonlinear, and ultrafast spectroscopies. The underlying near-field interaction mediated by the atomic-force or scanning tunneling microscope tip provides the desired deep-sub wavelength nano-focusing enabling few-nm spatial resolution. I will introduce our generalization of the approach in terms of the near-field impedance matching to a quantum system based on special optical antenna-tip designs. The resulting enhanced and qualitatively new forms of light-matter interaction enable measurements of quantum dynamics in an interacting environment or to image the electromagnetic local density of states of thermal radiation. Other applications include the inter-molecular coupling and dynamics in soft-matter hetero-structures, surface plasmon interferometry as a probe of electronic structure and dynamics in graphene, and quantum phase transitions in correlated electron materials. These examples highlight the general applicability of the new near-field microscopy approach, complementing emergent X-ray and electron imaging tools, aiming towards the ultimate goal of probing matter on its most elementary spatio-temporal level.

  4. Snow cover detection algorithm using dynamic time warping method and reflectances of MODIS solar spectrum channels

    Science.gov (United States)

    Lee, Kyeong-sang; Choi, Sungwon; Seo, Minji; Lee, Chang suk; Seong, Noh-hun; Han, Kyung-Soo

    2016-10-01

    Snow cover is biggest single component of cryosphere. The Snow is covering the ground in the Northern Hemisphere approximately 50% in winter season and is one of climate factors that affects Earth's energy budget because it has higher reflectance than other land types. Also, snow cover has an important role about hydrological modeling and water resource management. For this reason, accurate detection of snow cover acts as an essential element for regional water resource management. Snow cover detection using satellite-based data have some advantages such as obtaining wide spatial range data and time-series observations periodically. In the case of snow cover detection using satellite data, the discrimination of snow and cloud is very important. Typically, Misclassified cloud and snow pixel can lead directly to error factor for retrieval of satellite-based surface products. However, classification of snow and cloud is difficult because cloud and snow have similar optical characteristics and are composed of water or ice. But cloud and snow has different reflectance in 1.5 1.7 μm wavelength because cloud has lower grain size and moisture content than snow. So, cloud and snow shows difference reflectance patterns change according to wavelength. Therefore, in this study, we perform algorithm for classifying snow cover and cloud with satellite-based data using Dynamic Time Warping (DTW) method which is one of commonly used pattern analysis such as speech and fingerprint recognitions and reflectance spectral library of snow and cloud. Reflectance spectral library is constructed in advance using MOD21km (MODIS Level1 swath 1km) data that their reflectance is six channels including 3 (0.466μm), 4 (0.554μm), 1 (0.647μm), 2 (0.857μm), 26 (1.382μm) and 6 (1.629μm). We validate our result using MODIS RGB image and MOD10 L2 swath (MODIS swath snow cover product). And we use PA (Producer's Accuracy), UA (User's Accuracy) and CI (Comparison Index) as validation criteria

  5. Evaluation of flow velocities after carotid artery stenting through split spectrum Doppler optical coherence tomography and computational fluid dynamics modeling.

    Science.gov (United States)

    Vuong, Barry; Genis, Helen; Wong, Ronnie; Ramjist, Joel; Jivraj, Jamil; Farooq, Hamza; Sun, Cuiru; Yang, Victor X D

    2014-12-01

    Hemodynamics plays a critical role in the development of atherosclerosis, specifically in regions of curved vasculature such as bifurcations exhibiting irregular blood flow profiles. Carotid atherosclerotic disease can be intervened by stent implantation, but this may result in greater alterations to local blood flow and consequently further complications. This study demonstrates the use of a variant of Doppler optical coherence tomography (DOCT) known as split spectrum DOCT (ssDOCT) to evaluate hemodynamic patterns both before and after stent implantation in the bifurcation junction in the internal carotid artery (ICA). Computational fluid dynamics (CFD) models were constructed to simulate blood velocity profiles and compared to the findings achieved through ssDOCT images. Both methods demonstrated noticeable alterations in hemodynamic patterns following stent implantation, with features such as slow velocity regions at the neck of the bifurcation and recirculation zones at the stent struts. Strong correlation between CFD models and ssDOCT images demonstrate the potential of ssDOCT imaging in the optimization of stent implantation in the clinical setting.

  6. Effects of spatial size, lattice doubling and source operator on the hadron spectrum with dynamical staggered quarks

    CERN Document Server

    Bitar, K M; Gottlieb, S; Heller, U M; Kennedy, A D; Kogut, J B; Krasnitz, A; Liu, W; Ogilvie, M C; Renken, R L; Sinclair, D K; Sugar, R L; Toussaint, D; Wang, K C; Bitar, Khalil M.; Gottlieb, Steven; Ogilvie, Michael C.

    1994-01-01

    We have extended our previous study of the lattice QCD spectrum with 2 flavors of staggered dynamical quarks at $6/g^2=5.6$ and $am_q=0.025$ and 0.01 to larger lattices, with better statistics and with additional sources for the propagators. The additional sources allowed us to estimate the $\\Delta$ mass and to measure the masses of all mesons whose operators are local in time. These mesons show good evidence for flavor symmetry restoration, except for the masses of the Goldstone and non-Goldstone pions. PCAC is observed in that $m_\\pi^2 \\propto m_q$, and $f_\\pi$ is estimated. Use of undoubled lattices removes problems with the pion propagator found in our earlier work. Previously we found a large change in the nucleon mass at a quark mass of $am_q=0.01$ when we increased the spatial size from 12 to 16. No such effect is observed at the larger quark mass, $am_q=0.025$. Two kinds of wall source were used, and we have found difficulties in getting consistent results for the nucleon mass between the two sources.

  7. Dynamics of air avalanches in the access pit of an underground quarry.

    Science.gov (United States)

    Perrier, F; Morat, P; Le Mouël, J-L

    2002-09-23

    Temperature measurements have been performed in the vertical access pit of an underground quarry. During autumn, air avalanches induce an initial thermal feedback and a stationary mixing state characterized by spatially coherent broad-band fluctuations with a standard deviation of about 0.2 degrees C, linearly increasing with the inside-minus-outside temperature difference. Phase changes of water are shown to contribute to the onset condition, the feedback, and the stationary mixing state. This experiment may give insight on turbulent thermal and compositional convection with nonadiabatic boundaries.

  8. Population Dynamics and Emission Spectrum of a Cascade Three-Level Jaynes-Cummings Model with Intensity-Dependent Coupling in a Kerr-like Medium

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    By using the method of eigenvectors, the atomic populations and emission spectrum are investigated in a system that consists of a cascade three-level atom resonantly interacting with a single-mode field in a Kerr-like medium.The atom and the field are assumed to be initially in the upper atomic state and the Fock state, respectively. Results for models with intensity-dependent coupling and with intensity-independent coupling are compared. It is found that both population dynamics and emission spectrum show no indications of atom-field decoupling in the strong field limit if the intensity-dependent coupling is taken into account.

  9. A game algorithm of dynamic spectrum allocation based on spectrum difference%基于频谱差异的动态频谱分配博弈算法

    Institute of Scientific and Technical Information of China (English)

    张新春; 何世彪; 葛利嘉; 孙江

    2012-01-01

    Came theory-based dynamic spectrum allocation of cognitive radio is one of the hot research of cognitive radio. Taking into account differences of the spectrum, using a Cournot game model, and adding the spectral similarity matrix to the original pricing function, a new utility function that makes the spectrum allocation more close to the actual network environment is proposed. Performance analysis shows that, the allocation algorithm considering the differences in the spectrum is more diverse than the original algorithm, and is suitable for the actual network.%基于博弈论的认知无线电动态频谱分配,是目前认知无线电领域研究的热点之一.考虑到频谱差异性,采用古诺博弈( Cournot game)模型,在原有的定价函数中加入频谱相似度矩阵,提出了新的效用函数,使得更接近于实际网络环境.性能分析表明,考虑了频谱差异性的分配算法较原来算法更具多样性,适合实际网络分配.

  10. Enabling dynamic access to dynamic petascale Earth Systems and Environmental data collections is easy: citing and reproducing the actual data extracts used in research publications is NOT

    Science.gov (United States)

    Wyborn, L. A.; Wang, J.; Si, W.; Druken, K. A.; Evans, B. J. K.; Klump, J. F.; Car, N. J.; Trenham, C.

    2015-12-01

    The National Computational Infrastructure (NCI) at the Australian National University (ANU) has collocated over 10 PB of national and international Earth Systems and Environmental data assets within a HPC facility to create the National Environmental Research Data Interoperability Platform (NERDIP). Data are replicated to, or are produced at, NCI: in many cases they are processed to higher-level data products. Individual data sets within these collections can range from multi-petabyte climate models and large volume raster arrays, down to gigabyte size, ultra-high resolution data sets. All data are quality assured to being 'published' and made accessible as services. Persistent identifiers are assigned during publishing at both the collection and data set level: the granularity and version control on persistent identifiers depend on the dataset. However, most NERDIP collections are dynamic: either new data is being appended, or else models/derivative products are being revised with new data, or changed as processing methods are improved. Further, because the data are accessible as services, researchers can log in and dynamically create user-defined subsets for specific research projects: inevitably such extracts underpin traditional 'publications'. Being able to reproduce these exact data extracts can be difficult and for the very larger data sets preserving a copy of large data extracts is out of the question. A solution is for the researcher to use provenance workflows that at a minimum capture the version of the data set used, the query and the time of extraction. In parallel, the data provider needs to implement version controls on the data and deploy tracking systems that time stamp when new data are appended, or when modifications are made to existing data and record what these changes are. Where, when and how persistent identifiers are minted on these large and dynamically changing data sets is still open to debate.

  11. Dynamic access clustering selecting mechanism based on Markov decision process for MANET

    Institute of Scientific and Technical Information of China (English)

    WANG Dao-yuan; TIAN Hui

    2007-01-01

    Clustering is an important method in the mobile Ad-hoc network (MANET). As a result of their mobility, the cluster selection is inevitable for the mobile nodes during their roaming between the different clusters. In this study, based on the analysis of the cluster-selecting problem in the environment containing multiple clusters, which are overlaying and intercrossing, a novel dynamic selecting mechanism is proposed to resolve the dynamic selection optimization of roaming between the different clusters in MANET. This selecting mechanism is also based on the consideration of the stability of communication system, the communicating bandwidth, and the effect of cluster selecting on the communication and also in accordance with the Markov decision-making model.

  12. Accessing Rydberg-dressed interactions using many-body Ramsey dynamics

    Science.gov (United States)

    Mukherjee, Rick; Killian, Thomas C.; Hazzard, Kaden R. A.

    2016-11-01

    We demonstrate that Ramsey spectroscopy can be used to observe Rydberg-dressed interactions in a many-body system well within experimentally measured lifetimes, in contrast to previous research, which either focused on interactions near Förster resonances or on few-atom systems. We build a spin-1/2 from one level that is Rydberg-dressed and another that is not. These levels may be hyperfine or long-lived electronic states. An Ising spin model governs the Ramsey dynamics, which we demonstrate can be used to characterize the Rydberg-dressed interactions. Furthermore, the dynamics can differ significantly from that observed in other spin systems. As one example, spin echo can increase the rate at which coherence decays. The results also apply to bare (undressed) Rydberg states as a special case, for which we quantitatively reproduce recent ultrafast experiments without fitting.

  13. Political settlement dynamics in a limited-access order: The case of Bangladesh

    OpenAIRE

    Mirza Hassan

    2013-01-01

    This study explores the dynamics of the elite political settlement in Bangladesh during the last two decades (1991-2012), as well as its impact on economic development and political development, understood here as the process of maintaining a stable balance between state building, rule of law consolidation, and democratisation (Fukuyama, 2011). The concept of political settlement is crucial for understanding the dominant social order in Bangladesh: the disaggregation of the country's limited-...

  14. DYNAMIC COMPLEMENTARITY IN EXPORT PROMOTION: THE MARKET ACCESS PROGRAM IN FRUITS AND VEGETABLES

    OpenAIRE

    Richards, Timothy J.; Patterson, Paul M.

    1998-01-01

    Government-supported promotion in foreign markets may justified when market failures exist, such as spillover externalities, where promotion of one commodity positively influences exports of another, or when market uncertainties cause planning horizons to be shorter than the persistent effects of promotion. A dynamic model of U.S. apple, almond, grape, and wine export supply is developed to test for these market failures. Promotion is viewed as an investment in establishing and maintaining a ...

  15. PMMA/PMMA core-shell particles with ellipsoidal, fluorescent cores: accessing rotational dynamics.

    Science.gov (United States)

    Klein, Matthias K; Klinkenberg, Nele; Schuetter, Stefan; Saenger, Nicolai; Pfleiderer, Patrick; Zumbusch, Andreas

    2015-03-10

    For several decades, nonaqueous dispersions of PMMA particles have played an important role in colloid research. They have found application as colloidal model systems, which are used to probe glassy dynamics or to explore crystal nucleation. To date, most research has focused on spherical particles, in which only translational motion can be investigated. Recently, however, there has been a surge of interest in analyzing also rotational dynamics. In this contribution, we introduce a new class of core-shell particles, which can be used as rotational probes. The colloids described herein are composed of shape anisotropic, fluorescent cores covered with nonfluorescent PMMA shells. The core-shell particles are built up in four steps. In a first step, we produce fluorescent and photo-cross-linkable PMMA colloids. In the second step, these particles are thermomechanically elongated and fixed in defined ellipsoidal shapes by photo-cross-linking. Subsequently, we cover the cross-linked, fluorescent core with a nonfluorescent PMMA shell. The shape of the resulting core-shell colloids is tunable between the initial anisotropic and perfect spherical shape. For shaping, we apply a simple solvent swelling procedure. As one option, this method yields perfect PMMA spheres with ellipsoidal, fluorescent centers. We also report morphological particle characterization using various fluorescence microscopy techniques. Finally, we demonstrate that the rotational dynamics of individual colloids can be tracked and analyzed.

  16. A nomadic access mechanism for enabling dynamic video surveillance over IEEE 802.15.4 networks

    Science.gov (United States)

    Garcia-Sanchez, Felipe; Garcia-Sanchez, Antonio-Javier; Losilla, Fernando; Garcia-Haro, Joan

    2010-12-01

    IEEE 802.15.4 networking technology is designed to be the common standard for integrating WSN applications in heterogeneous environments. However, applications considering mobile nodes along with strict temporal requirements, such as those required for video transmission, are an unexplored field for this technology. These applications involve different challenges and issues that the direct employment of the IEEE 802.15.4 standard does not resolve. Therefore, in this paper a cross-layer mechanism consisting of application and medium access arbitration is presented, enabling the efficient connection and operation of mobile nodes together with the transmission of video flows. The proposed mechanism is evaluated via simulation and its feasibility checked by means of a first prototype. The study of power consumption is also taken into account and so are the quality of service parameters and the human quality perception of the received video stream. The results obtained are presented and further discussed.

  17. Virtual fabrication using directed self-assembly for process optimization in a 14-nm dynamic random access memory

    Science.gov (United States)

    Kamon, Mattan; Akbulut, Mustafa; Yan, Yiguang; Faken, Daniel; Pap, Andras; Allampalli, Vasanth; Greiner, Ken; Fried, David

    2016-07-01

    For directed self-assembly (DSA) to be deployed in advanced semiconductor technologies, it must reliably integrate into a full process flow. We present a methodology for using virtual fabrication software, including predictive DSA process models, to develop and analyze the replacement of self-aligned quadruple patterning with Liu-Nealey chemoepitaxy on a 14-nm dynamic random access memory (DRAM) process. To quantify the impact of this module replacement, we investigated a key process yield metric for DRAM, interface area between the capacitor contacts and transistor source/drain. Additionally, we demonstrate virtual fabrication of the DRAM cell's hexagonally packed capacitors patterned with an array of diblock copolymer cylinders in place of fourfold litho-etch (LE4) patterning.

  18. An Agent-Based Fuzzy Collaborative Intelligence Approach for Predicting the Price of a Dynamic Random Access Memory (DRAM Product

    Directory of Open Access Journals (Sweden)

    Toly Chen

    2012-05-01

    Full Text Available Predicting the price of a dynamic random access memory (DRAM product is a critical task to the manufacturer. However, it is not easy to contend with the uncertainty of the price. In order to effectively predict the price of a DRAM product, an agent-based fuzzy collaborative intelligence approach is proposed in this study. In the agent-based fuzzy collaborative intelligence approach, each agent uses a fuzzy neural network to predict the DRAM price based on its view. The agent then communicates its view and forecasting results to other agents with the aid of an automatic collaboration mechanism. According to the experimental results, the overall performance was improved through the agents’ collaboration.

  19. Variable weight Khazani-Syed code using hybrid fixed-dynamic technique for optical code division multiple access system

    Science.gov (United States)

    Anas, Siti Barirah Ahmad; Seyedzadeh, Saleh; Mokhtar, Makhfudzah; Sahbudin, Ratna Kalos Zakiah

    2016-10-01

    Future Internet consists of a wide spectrum of applications with different bit rates and quality of service (QoS) requirements. Prioritizing the services is essential to ensure that the delivery of information is at its best. Existing technologies have demonstrated how service differentiation techniques can be implemented in optical networks using data link and network layer operations. However, a physical layer approach can further improve system performance at a prescribed received signal quality by applying control at the bit level. This paper proposes a coding algorithm to support optical domain service differentiation using spectral amplitude coding techniques within an optical code division multiple access (OCDMA) scenario. A particular user or service has a varying weight applied to obtain the desired signal quality. The properties of the new code are compared with other OCDMA codes proposed for service differentiation. In addition, a mathematical model is developed for performance evaluation of the proposed code using two different detection techniques, namely direct decoding and complementary subtraction.

  20. [Application of wavelet transform on improving detecting precision of the non-invasive blood components measurement based on dynamic spectrum method].

    Science.gov (United States)

    Li, Gang; Men, Jian-Long; Sun, Zhao-Min; Wang, Hui-Quan; Lin, Ling; Tong, Ying; Zhang, Bao-Ju

    2011-02-01

    Time-varying noises in spectra collection process have influence on the prediction accuracy of quantitative calibration in the non-invasive blood components measurement which is based on dynamic spectrum (DS) method. By wavelet transform, we focused on the absorbance wave of fingertip transmission spectrum in pulse frequency band. Then we increased the signal to noise ratio of DS data, and improved the detecting precision of quantitative calibration. After carrying out spectrum data continuous acquisition of the same subject for 10 times, we used wavelet transform de-noising to increase the average correlation coefficient of DS data from 0.979 6 to 0.990 3. BP neural network was used to establish the calibration model of subjects' blood components concentration values against dynamic spectrum data of 110 volunteers. After wavelet transform de-noising, the correlation coefficient of prediction set increased from 0.677 4 to 0.846 8, and the average relative error was decreased from 15.8% to 5.3%. Experimental results showed that the introduction of wavelet transform can effectively remove the noise in DS data, improve the detecting precision, and accelerate the development of non-invasive blood components measurement based on DS method.

  1. X-Ray Emitting GHz-Peaked Spectrum Galaxies: Testing a Dynamical-Radiative Model with Broad-Band Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Ostorero, L.; /Turin U. /INFN, Turin; Moderski, R.; /Warsaw, Copernicus Astron. Ctr. /KIPAC, Menlo Park; Stawarz, L.; /KIPAC, Menlo Park /Jagiellonian U., Astron. Observ.; Diaferio, A.; /Turin U. /INFN, Turin; Kowalska, I.; /Warsaw U. Observ.; Cheung, C.C.; /NASA, Goddard /Naval Research Lab, Wash., D.C.; Kataoka, J.; /Waseda U., RISE; Begelman, M.C.; /JILA, Boulder; Wagner, S.J.; /Heidelberg Observ.

    2010-06-07

    In a dynamical-radiative model we recently developed to describe the physics of compact, GHz-Peaked-Spectrum (GPS) sources, the relativistic jets propagate across the inner, kpc-sized region of the host galaxy, while the electron population of the expanding lobes evolves and emits synchrotron and inverse-Compton (IC) radiation. Interstellar-medium gas clouds engulfed by the expanding lobes, and photoionized by the active nucleus, are responsible for the radio spectral turnover through free-free absorption (FFA) of the synchrotron photons. The model provides a description of the evolution of the GPS spectral energy distribution (SED) with the source expansion, predicting significant and complex high-energy emission, from the X-ray to the {gamma}-ray frequency domain. Here, we test this model with the broad-band SEDs of a sample of eleven X-ray emitting GPS galaxies with Compact-Symmetric-Object (CSO) morphology, and show that: (i) the shape of the radio continuum at frequencies lower than the spectral turnover is indeed well accounted for by the FFA mechanism; (ii) the observed X-ray spectra can be interpreted as non-thermal radiation produced via IC scattering of the local radiation fields off the lobe particles, providing a viable alternative to the thermal, accretion-disk dominated scenario. We also show that the relation between the hydrogen column densities derived from the X-ray (N{sub H}) and radio (N{sub HI}) data of the sources is suggestive of a positive correlation, which, if confirmed by future observations, would provide further support to our scenario of high-energy emitting lobes.

  2. Infrared Chemical Nano-Imaging: Accessing Structure, Coupling, and Dynamics on Molecular Length Scales

    Energy Technology Data Exchange (ETDEWEB)

    Muller, Eric A.; Pollard, Benjamin; Raschke, Markus Bernd

    2015-04-02

    This Perspective highlights recent advances in infrared vibrational chemical nano-imaging. In its implementations of scattering scanning near-field optical microscopy (s-SNOM) and photothermal-induced resonance (PTIR), IR nanospectroscopy provides few-nanometer spatial resolution for the investigation of polymer, biomaterial, and related soft-matter surfaces and nanostructures. Broad-band IR s-SNOM with coherent laser and synchrotron sources allows for chemical recognition with small-ensemble sensitivity and the potential for sensitivity reaching the single-molecule limit. Probing selected vibrational marker resonances, it gives access to nanoscale chemical imaging of composition, domain morphologies, order/disorder, molecular orientation, or crystallographic phases. Local intra- and intermolecular coupling can be measured through frequency shifts of a vibrational marker in heterogeneous environments and associated inhomogeneities in vibrational dephasing. In combination with ultrafast spectroscopy, the vibrational coherent evolution of homogeneous sub-ensembles coupled to their environment can be observed. Outstanding challenges are discussed in terms of extensions to coherent and multidimensional spectroscopies, implementation in liquid and in situ environments, general sample limitations, and engineering s-SNOM scanning probes to better control the nano-localized optical excitation and to increase sensitivity.

  3. Lossless compression of very large volume data with fast dynamic access

    Science.gov (United States)

    Zhao, Rongkai; Tao, Tao; Gabriel, Michael; Belford, Geneva

    2002-09-01

    The volumetric data set is important in many scientific and biomedical fields. Since such sets may be extremely large, a compression method is critical to store and transmit them. To achieve a high compression rate, most of the existing volume compression methods are lossy, which is usually unacceptable in biomedical applications. We developed a new context-based non-linear prediction method to preprocess the volume data set in order to effectively lower the prediction entropy. The prediction error is further encoded using Huffman code. Unlike the conventional methods, the volume is divided into cubical blocks to take advantage of the data's spatial locality. Instead of building one Huffman tree for each block, we developed a novel binning algorithm that build a Huffman tree for each group (bin) of blocks. Combining all the effects above, we achieved an excellent compression rate compared to other lossless volume compression methods. In addition, an auxiliary data structure, Scalable Hyperspace File (SHSF) is used to index the huge volume so that we can obtain many other benefits including parallel construction, on-the-fly accessing of compressed data without global decompression, fast previewing, efficient background compressing, and scalability etc.

  4. THE DYNAMICS OF FOREIGN DIRECT INVESTMENT IN ROMANIA AFTER EU ACCESSION

    Directory of Open Access Journals (Sweden)

    Nicoleta Rusu

    2010-12-01

    Full Text Available Identification of potential investment of the countries in the current context is one of the main important problem of the world economy because the investments, particularly foreign ones, is considered the key factor for economic growth and development. Foreign direct investments are an alternative source for financing the national economy, with a tendency in recent years of a positive effect on the Romanian economy. This paperwork highlights the role of foreign direct investment in Romania's economical growth potential, with major impact on employment, on the economic modernization, technology transfer and on the living standards. At the same time the article analyzed and highlights the contains of the current trend of foreign direct investments, structure and dynamics after Romania joined the European Union and their geographical distribution on the main development regions.

  5. Advancing Access to New Technology for Sustained High Resolution Observations of Plankton: From Bloom Dynamics to Climate Change

    Science.gov (United States)

    Sosik, H. M.; Olson, R. J.

    2012-12-01

    The combination of ocean observatory infrastructure and automated submersible flow cytometry can provide unprecedented capability for sustained high resolution time series of plankton, including taxa that are harmful or early indicators of ecosystem response to environmental change. Over the past decade, we have developed the FlowCytobot series of instruments that exemplify this capability. FlowCytobot and Imaging FlowCytobot use a combination of laser-based scattering and fluorescence measurements and video imaging of individual particles to enumerate and characterize cells ranging from picocyanobacteria to large chaining-forming diatoms. The process of developing these complex instruments was streamlined by access to the Martha's Vineyard Coastal Observatory (MVCO), a cabled facility on the New England Shelf, where real time two-way communications and access to shore power expedited cycles of instrument evaluation and design refinement. Repeated deployments at MVCO, typically 6 months in duration, have produced multi-year high resolution (hourly to daily) time series that are providing new insights into dynamics of community structure such as blooms, seasonality, and possibly even trends linked to regional climate change. The high temporal resolution observations of single cell properties make it possible not only to characterize taxonomic composition and size structure, but also to quantify taxon-specific growth rates. To meet the challenge of broadening access to this enabling technology, we have taken a two-step approach. First, we are partnering with a few scientific collaborators interested in using the instruments in different environments and to address different applications, notably the detection and characterization of harmful algal bloom events. Collaboration at this stage ensured that these first users outside the developers' lab had access to technical know-how required for successful outcomes; it also provided additional feedback that could be

  6. Spectrum Sharing Security and Attacks in CRNs: a Review

    Directory of Open Access Journals (Sweden)

    Wajdi Alhakami

    2014-01-01

    Full Text Available Cognitive Radio plays a major part in communication technology by resolving the shortage of the spectrum through usage of dynamic spectrum access and artificial intelligence characteristics. The element of spectrum sharing in cognitive radio is a fundamental approach in utilising free channels. Cooperatively communicating cognitive radio devices use the common control channel of the cognitive radio medium access control to achieve spectrum sharing. Thus, the common control channel and consequently spectrum sharing security are vital to ensuring security in the subsequent data communication among cognitive radio nodes. In addition to well known security problems in wireless networks, cognitive radio networks introduce new classes of security threats and challenges, such as licensed user emulation attacks in spectrum sensing and misbehaviours in the common control channel transactions, which degrade the overall network operation and performance. This review paper briefly presents the known threats and attacks in wireless networks before it looks into the concept of cognitive radio and its main functionality. The paper then mainly focuses on spectrum sharing security and its related challenges. Since spectrum sharing is enabled through usage of the common control channel, more attention is paid to the security of the common control channel by looking into its security threats as well as protection and detection mechanisms. Finally, the pros and cons as well as the comparisons of different CR-specific security mechanisms are presented with some open research issues and challenges.

  7. New binding site conformations of the dengue virus NS3 protease accessed by molecular dynamics simulation.

    Directory of Open Access Journals (Sweden)

    Hugo de Almeida

    Full Text Available Dengue fever is caused by four distinct serotypes of the dengue virus (DENV1-4, and is estimated to affect over 500 million people every year. Presently, there are no vaccines or antiviral treatments for this disease. Among the possible targets to fight dengue fever is the viral NS3 protease (NS3PRO, which is in part responsible for viral processing and replication. It is now widely recognized that virtual screening campaigns should consider the flexibility of target protein by using multiple active conformational states. The flexibility of the DENV NS3PRO could explain the relatively low success of previous virtual screening studies. In this first work, we explore the DENV NS3PRO conformational states obtained from molecular dynamics (MD simulations to take into account protease flexibility during the virtual screening/docking process. To do so, we built a full NS3PRO model by multiple template homology modeling. The model comprised the NS2B cofactor (essential to the NS3PRO activation, a glycine flexible link and the proteolytic domain. MD simulations had the purpose to sample, as closely as possible, the ligand binding site conformational landscape prior to inhibitor binding. The obtained conformational MD sample was clustered into four families that, together with principal component analysis of the trajectory, demonstrated protein flexibility. These results allowed the description of multiple binding modes for the Bz-Nle-Lys-Arg-Arg-H inhibitor, as verified by binding plots and pair interaction analysis. This study allowed us to tackle protein flexibility in our virtual screening campaign against the dengue virus NS3 protease.

  8. Dynamical properties of total intensity fluctuation spectrum in two-mode Nd:YVO4 microchip laser

    Science.gov (United States)

    Zhang, Shao-Hui; Shu-Lian, Zhang; Tan, Yi-Dong; Sun, Li-Qun

    2015-12-01

    We investigate the total intensity fluctuation spectrum of the two-longitudinal- mode Nd:YVO4 microchip laser (ML). We find that low-frequency relaxation oscillation (RO) peaks still appear in the total intensity fluctuation spectrum, which is different from a previous research result that the low-frequency RO peaks exist in the spectrum of the individual mode but compensate for each other totally in the total intensity fluctuation spectrum. Taking the spatial hole-burning effect into account, one and two-mode rate equations for Nd:YVO4 ML laser are established and studied. Based on the theoretical model, we find that when the gains and losses for two longitudinal models are different, a low-frequency RO peak will appear in the total intensity fluctuation spectrum, while when they share the same gain and loss, the total spectrum will behave like that of a single mode laser. Theoretical simulation results coincide with experimental results very well. Project supported by the Beijing Higher Education Young Elite Teacher Project, China (Grant No. YETP0086), the Tsinghua University Initiative Scientific Research Programme, China (Grant No. 2012Z02166), and the Special-funded Programme on National Key Scientific Instruments and Equipment Development of China (Grant No. 2011YQ04013603).

  9. Neutron dynamics of fast-spectrum dedicated cores for waste transmutation; Etude et amelioration du comportement cinetique de coeurs rapides a la transmutation de dechets a vie longue

    Energy Technology Data Exchange (ETDEWEB)

    Massara, S

    2002-04-01

    Among different scenarios achieving minor actinide transmutation, the possibility of double strata scenarios with critical, fast spectrum, dedicated cores must be checked and quantified. In these cores, the waste fraction has to be at the highest level compatible with safety requirements during normal operation and transient conditions. As reactivity coefficients are poor in such critical cores (low delayed neutron fraction and Doppler feed-back, high coolant void coefficient), their dynamic behaviour during transient conditions must be carefully analysed. Three nitride-fuel configurations have been analysed: two liquid metal-cooled (sodium and lead) and a particle-fuel helium-cooled one. A dynamic code, MAT4 DYN, has been developed during the PhD thesis, allowing the study of loss of flow, reactivity insertion and loss of coolant accidents, and taking into account two fuel geometries (cylindrical and spherical) and two thermal-hydraulics models for the coolant (incompressible for liquid metals and compressible for helium). Dynamics calculations have shown that if the fuel nature is appropriately chosen (letting a sufficient margin during transients), this can counterbalance the bad state of reactivity coefficients for liquid metal-cooled cores, thus proving the interest of this kind of concept. On the other side, the gas-cooled core dynamics is very badly affected by the high value of the helium void coefficient (which is a consequence of the choice of a hard spectrum), this effect being amplified by the very low thermal inertia of particle-fuel design. So, a new kind of concept should be considered for a helium-cooled fast-spectrum dedicated core. (authors)

  10. Report to the President: Realizing the Full Potential of Government-Held Spectrum to Spur Economic Growth

    Science.gov (United States)

    2012-07-01

    lists the major wireless network equipment vendors as Ericcson, Nokia , Huawei, Alcatel­Lucent, and ZTE. Box 1.1: Unlicensed Spectrum Explained...Europe including a proposal from Nokia and Qualcomm called the Authorized Shared Access (ASA)/Licensed Shared Access (LSA) system, the Wireless Access... Nokia ,116 enabled the dynamic use of spec- trum whenever it was unused by an incumbent user. It deployed cognitive radio techniques, geo-location

  11. 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.

  12. Impaired Overt Facial Mimicry in Response to Dynamic Facial Expressions in High-Functioning Autism Spectrum Disorders

    Science.gov (United States)

    Yoshimura, Sayaka; Sato, Wataru; Uono, Shota; Toichi, Motomi

    2015-01-01

    Previous electromyographic studies have reported that individuals with autism spectrum disorders (ASD) exhibited atypical patterns of facial muscle activity in response to facial expression stimuli. However, whether such activity is expressed in visible facial mimicry remains unknown. To investigate this issue, we videotaped facial responses in…

  13. Evaluation of Kolmogorov - Smirnov Test and Energy Detector Techniques for Cooperative Spectrum Sensing in Real Channel Conditions

    Directory of Open Access Journals (Sweden)

    D. Lekomtcev

    2015-06-01

    Full Text Available The cognitive radio technology allows solving one of the main issues of current wireless communication technologies, namely a deficit of vacant spectrum. A dynamic spectrum access used in the cognitive radio networks (CRN gives an ability to access an unused spectrum in real time. Cooperative spectrum sensing is the most effective method for spectrum holes detecting. It combines sensing information of multiple cognitive radio users. In this paper, an experimental evaluation of spectrum sensing methods based on the Kolmogorov - Smirnov statistical test and Energy Detector using the Universal Software Radio Peripheral (USRP devices synchronized through a MIMO cable and with further processing in the GNU Radio and Matlab software are presented. Three hard decision fusion schemes are analyzed. Simulation comparison between these rules is presented via Receiver Operating Characteristic (ROC curves. The influence of real channel with interferences is compared in contrast to commonly assumed AWGN channel model of vacant channel noise.

  14. Different visual preference patterns in response to simple and complex dynamic social stimuli in preschool-aged children with autism spectrum disorders.

    Directory of Open Access Journals (Sweden)

    Lijuan Shi

    Full Text Available Eye-tracking studies in young children with autism spectrum disorder (ASD have shown a visual attention preference for geometric patterns when viewing paired dynamic social images (DSIs and dynamic geometric images (DGIs. In the present study, eye-tracking of two different paired presentations of DSIs and DGIs was monitored in a group of 13 children aged 4 to 6 years with ASD and 20 chronologically age-matched typically developing children (TDC. The results indicated that compared with the control group, children with ASD attended significantly less to DSIs showing two or more children playing than to similar DSIs showing a single child. Visual attention preference in 4- to 6-year-old children with ASDs, therefore, appears to be modulated by the type of visual stimuli.

  15. On Two-Way Cooperative Spectrum Access Based on Power Allocation%基于功率分配的双向协作频谱接入方法

    Institute of Scientific and Technical Information of China (English)

    王凯; 卢为党; 郭淑琴; 何娣; 沈凌晓

    2015-01-01

    In this paper ,a two‐way cooperative spectrum access strategy based on power allocation has been proposed ,in w hich a secondary user can have access to the licensed spectrum of a primary system and use a fraction of the power to forward primary signals help the primary user achieve the target rate .Then it can use the remaining power to send its own signal .The optimal power allocation of the secondary user has been studied ,such that the transmission rate of the secondary system is maximized ,w hile guaranteeing the two primary users to achieve their target transmission rates .Numerical results verify the efficiency of the proposed strategy and show that both of the secondary user and the two primary users can gain benefit from the proposed strategy .%提出了一种基于功率分配的双向协作频谱接入方法。在该方法中,认知用户通过双向协作的方式接入授权用户频谱,使用一部分功率转发授权用户信息,帮助授权用户达到目标速率,然后使用剩余的功率发送自己的信息。该方法研究了认知用户如何对功率进行分配,在保证授权用户达到目标速率的条件下,最大化认知用户的速率。仿真结果验证了所提频谱接入方法的有效性,同时说明授权用户和认知用户都能够从所提频谱接入方法中获得好处。

  16. 一种基于动态博弈模型的频谱分配策略%A Spectrum Allocation Strategy Based on Dynamic Game Model

    Institute of Scientific and Technical Information of China (English)

    何庆; 徐同伟; 吴意乐; 魏伦炳

    2015-01-01

    为了更好地解决认知用户的频谱分配问题,保证不同认知用户的收益和分配的公平性,提出了一种基于动态博弈模型的频谱分配策略.首先建立博弈模型,然后为使提供频谱的主用户的效用最大化,对认知用户的效用函数进行了改进,并分析了认知用户动态博弈系统的稳定性.实验结果表明:为保证系统的稳定性,认知用户经过多次博弈,最终达到了纳什均衡,并且在纳什均衡点处,使用户收益达到最大化.%In order to better solve the problem of spectrum allocation and ensure the fairness of different cognitive users' revenue and distribution,a spectrum allocation strategy based on dynamic game model was proposed. First,the game model was established. Then,the utility function was improved according to the utility maximiza-tion of the main users who provide spectrum and the stability of dynamic game system of cognitive users was ana-lyzed. The experimental results show that cognitive users make use of multiple games to ensure the stability of the system,and ultimately achieve the Nash equilibrium,the users achieve the maximum of revenues in the Nash e-quilibrium point.

  17. IR Spectrum Data Bank System

    Institute of Scientific and Technical Information of China (English)

    Xie Dilin

    2004-01-01

    The infrared spectra of pure compounds of ninety thousands, poly compounds of twelve thousand, drugs of one thousand were included in the data bank. All of them can be searched out according to their serial number, chemical name, commercial name, amount of each atoms, or molecular formula, as well as their spectrum peak appearances. Program for spectrum information inputting, program for spectrum information search and program for spectrum peak appearance search were included in the system; in addition, spectrum information data bank, spectrum peak code data bank and spectrum figure data bank were attached to the system. System program was written by Visial Basic, and run under Windows system. The spectrum information data bank and spectrum figure data bank were administrated by Microsoft Access.The program for spectrum message inputting can be used to add message data and spectrum figure of some new compounds into the data banks by users themselves. The program for spectrum message search was designed to find out all the message data and spectrum figure of interested compound according to someone of the message data. The program for spectrum peak search was designed to find out some spectra most similar in peak shape with unknown spectrum by peak to peak comparison. When the wavenumbers and transmittances of main peaks in the spectrum of unknown sample were entered, the spectrum peak search was performed and several hits with higher similarity were reported including their similarity scores, spectrum serial numbers, sample's states,melt points, molecular formulas as well as spectrum images. If the search result was not satisfactory,some methods to modify spectrum parameters were reminded and search was performed again.

  18. Transmission Dynamics of Extended-Spectrum β-lactamase–Producing Enterobacteriaceae in the Tertiary Care Hospital and the Household Setting

    OpenAIRE

    2012-01-01

    Background . Studies about transmission rates of extended-spectrum β-lactamase (ESBL)–producing Enterobacteriaceae in hospitals and households are scarce. Methods . Eighty-two index patients with new carriage of ESBL-producing Escherichia coli (ESBL-Ec; n = 72) or ESBL-producing Klebsiella pneumoniae (ESBL-Kp; n = 10) and their hospital (n = 112) and household (n = 96) contacts were studied prospectively from May 2008 through September 2010. Isolates were phenotypically and molecularly charac...

  19. Separation of coexisting dynamical regimes in multistate intermittency based on wavelet spectrum energies in an erbium-doped fiber laser.

    Science.gov (United States)

    Hramov, Alexander E; Koronovskii, Alexey A; Moskalenko, Olga I; Zhuravlev, Maksim O; Jaimes-Reategui, Rider; Pisarchik, Alexander N

    2016-05-01

    We propose a method for the detection and localization of different types of coexisting oscillatory regimes that alternate with each other leading to multistate intermittency. Our approach is based on consideration of wavelet spectrum energies. The proposed technique is tested in an erbium-doped fiber laser with four coexisting periodic orbits, where external noise induces intermittent switches between the coexisting states. Statistical characteristics of multistate intermittency, such as the mean duration of the phases for every oscillation type, are examined with the help of the developed method. We demonstrate strong advantages of the proposed technique over previously used amplitude methods.

  20. 适用于异构QoS环境的伺机频谱接入策略设计%Opportunistic Spectrum Access Strategy Design in Heterogeneous QoS Environment

    Institute of Scientific and Technical Information of China (English)

    王凡; 姚富强; 赵杭生; 冯少栋; 张建照

    2013-01-01

    Considering the scenario of cognitive radio Networks (CRN) single channel opportunistic spectrum access, a single channel opportunistic spectrum access model was established which provided CR QoS guarantee and also promised interference-free to primary radios (PR). The model aimed at maximizing the useful cognitive radio network (CRN) throughput which was a new metric defined. The minimum rate gap-based access strategy was proposed and the corresponding minimum rate gap based channel and power allocation (MRG-CPA) algorithm and MAC protocol was demonstrated. Simulation results show that MRG-CPA provides more useful CRN network throughput as well as improves the CR QoS guarantee rate than existing solutions such as the first Fit Deceasing algorithm, best fit deceasing algorithm and least rate requirement based channel and power allocation algorithm.%针对认知无线电网络(Cognitive Radio Network,CRN)中认知无线电(Cognitive Radio,CR)用户单信道伺机频谱接入问题,从既满足CR用户各异的QoS需求又不对主用户(Primary Radio,PR)产生干扰的角度,定义新的度量指标CRN有效吞吐量,并以CRN有效吞吐量最大为目标建立单信道伺机频谱接入模型.提出基于最小速率差额的接入策略,给出相应的信道和功率分配算法(Minimum Rate Gap-based Channel and Power Allocation,MRG-CPA),并设计MAC协议以实现分布式接入.仿真结果表明,与现有的降序最佳适应算法、降序首次适应算法和基于最小速率需求的功率分配算法相比,MRG-CPA不仅提供较大的CRN有效吞吐量,并且提高CR用户QoS保证率.

  1. 基于动态控制机制的工作流安全访问模型%Workflow Security Access Model Based on Dynamic Control Mechanism

    Institute of Scientific and Technical Information of China (English)

    巫茜; 周庆

    2012-01-01

    为确保工作流系统安全可靠地工作,在传统基于角色的访问控制模型中引入目标案例、用户管理和目标3个关系元素,设计动态授权机制,构建一种基于动态控制机制的工作流安全访问模型,通过基本约束关系与动态约束条件,保证模型的安全运行,并将其与工作流引擎组件进行集成,为独立安全领域应用提供安全授权服务.应用结果表明,该模型可将动态职责与互惠职责较好地分离,对动态职责进行绑定,为系统工作流安全访问提供技术支持.%In order to ensure the workflow system secure and reliable, this paper introduces three relation elements of Target Case(TC), User Management(UM) and Target(T) in the conventional access control model based on role, designs the dynamic authorization mechanism, and builds a sort of security access model in workflow based on dynamic control mechanism, which ensures the secure running of the model by means of basic constraint relation and dynamic constraint conditions. The model is integrated with workflow engine component to provide the security authorization service for the application of independent security field. Application results show that the model can better separate the dynamic responsibility and reciprocal responsibility, make the binding of dynamic responsibility, and provide technical support for security access of system workflow.

  2. Subthreshold K+ Channel Dynamics Interact With Stimulus Spectrum to Influence Temporal Coding in an Auditory Brain Stem Model

    Science.gov (United States)

    Day, Mitchell L.; Doiron, Brent; Rinzel, John

    2013-01-01

    Neurons in the auditory brain stem encode signals with exceptional temporal precision. A low-threshold potassium current, IKLT, present in many auditory brain stem structures and thought to enhance temporal encoding, facilitates spike selection of rapid input current transients through an associated dynamic gate. Whether the dynamic nature of IKLT interacts with the timescales in spectrally rich input to influence spike encoding remains unclear. We examine the general influence of IKLT on spike encoding of stochastic stimuli using a pattern classification analysis between spike responses from a ventral cochlear nucleus (VCN) model containing IKLT, and the same model with the dynamics removed. The influence of IKLT on spike encoding depended on the spectral content of the current stimulus such that maximal IKLT influence occurred for stimuli with power concentrated at frequencies low enough (<500 Hz) to allow IKLT activation. Further, broadband stimuli significantly decreased the influence of IKLT on spike encoding, suggesting that broadband stimuli are not well suited for investigating the influence of some dynamic membrane nonlinearities. Finally, pattern classification on spike responses was performed for physiologically realistic conductance stimuli created from various sounds filtered through an auditory nerve (AN) model. Regardless of the sound, the synaptic input arriving at VCN had similar low-pass power spectra, which led to a large influence of IKLT on spike encoding, suggesting that the subthreshold dynamics of IKLT plays a significant role in shaping the response of real auditory brain stem neurons. PMID:18057115

  3. Hadron Spectrum in QCD with Valence Wilson Fermions and Dynamical Staggered Fermions at $6/g^2=5.6$

    CERN Document Server

    Bitar, K M; Edwards, R G; Gottlieb, S; Heller, U M; Kennedy, A D; Kogut, J B; Krasnitz, A; Liu, W; Ogilvie, M C; Renken, R L; Rossi, P; Sinclair, D K; Sugar, R L; Toussaint, D; Wang, K C

    1992-01-01

    We present an analysis of hadronic spectroscopy for Wilson valence quarks with dynamical staggered fermions at lattice coupling $6/g^2 = \\beta=5.6$ at sea quark mass $am_q=0.01$ and 0.025, and of Wilson valence quarks in quenched approximation at $\\beta=5.85$ and 5.95, both on $16^3 \\times 32$ lattices. We make comparisons with our previous results with dynamical staggered fermions at the same parameter values but on $16^4$ lattices doubled in the temporal direction.

  4. Distributed Algorithms for Learning and Cognitive Medium Access with Logarithmic Regret

    Science.gov (United States)

    2010-06-08

    Sadler, “A Survey of Dynamic Spectrum Access,” IEEE Signal Proc. Mag., vol. 24, no. 3, pp. 79–89, 2007. [3] N. Cesa -Bianchi and G. Lugosi, Prediction...1995. [11] P. Auer, N. Cesa -Bianchi, and P. Fischer, “Finite-time Analysis of the Multiarmed Bandit Problem,” Machine Learning, vol. 47, no. 2, pp

  5. U_A(1) breaking at finite temperature from the Dirac spectrum with the dynamical HISQ action

    CERN Document Server

    Ohno, H; Karsch, F; Mukherjee, S

    2012-01-01

    We investigate $U_A(1)$ breaking above $T_c$ in terms of the Dirac spectrum on configurations with (2+1)-flavors, using the HISQ action. The strange quark mass is at its physical value. We use several light quark masses corresponding to the Goldstone pion masses in the range of about 115 -- 230 MeV on lattices of size 32$^3 \\times$8 and 48$^3 \\times$8. We calculate the 100 lowest-lying Dirac eigenvalues at temperatures below and above $T_c$. We investigate the volume dependence of the Dirac eigenvalue density to determine whether there is a gap around zero, which can appear if $U_A(1)$ symmetry is restored in the chiral symmetric phase. We also investigate the quark mass dependence of the Dirac eigenvalue density at zero and check whether there is a linear behavior that would signal the $U_A(1)$ breaking above $T_c$.

  6. Composite (Goldstone) Higgs Dynamics on the Lattice: Spectrum of SU(2) Gauge Theory with two Fundamental Fermions

    CERN Document Server

    Arthur, Rudy; Hansen, Martin; Hietanen, Ari; Lewis, Randy; Pica, Claudio; Sannino, Francesco

    2014-01-01

    We study the meson spectrum of the SU(2) gauge theory with two Wilson fermions in the fundamental representation. The theory unifies both Technicolor and composite Goldstone Boson Higgs models of electroweak symmetry breaking. We have calculated the masses of the lightest spin one vector and axial vector mesons. In addition, we have also obtained preliminary results for the mass of the lightest scalar (singlet) meson state. The simulations have been done with multiple masses and two different lattice spacings for chiral and continuum extrapolations. The spin one meson masses set lower limits for accelerator experiments, whereas the scalar meson will mix with a pGB of the theory and produce two scalar states. The lighter of the states is the 125 GeV Higgs boson, and the heavier would be a new yet unobserved scalar state.

  7. 一种基于用户评价值的动态访问控制模型%Dynamic access control model based on user evaluation value

    Institute of Scientific and Technical Information of China (English)

    高燕; 陈小辉; 张永恒

    2015-01-01

    In consideration of the problem that a lot of different users of the shopping websites have the same permissions though they have different credit rating,a dynamic access control model based on the user evaluation value is proposed. Assess permission authorization in RBAC and user evaluation value are combined in this model. By comprehensive evaluation of user evaluation value for shopping website,the permission scope of user is adjusted dynamically to achieve dynamic access control. The result of analyzing an example by this model shows that this access control model can improve the accuracy of user evalua⁃tion value. By the model,the dynamic permission assignment for the same roles with different permission was realized,and safe⁃ty and reliability of resources in shopping website were enhanced.%针对购物网站中大量信誉等级不同的用户却拥有相同权限的问题,提出一种依据用户评价值进行动态访问控制的模型。该模型将RBAC中权限的授权与用户的评价值相结合,通过综合评估购物网站用户评价值,对角色的权限范围进行动态调整,从而达到动态访问控制的目的。通过应用该模型对一个实例进行分析的结果表明,该访问控制模型能够提高用户评价值的准确性,实现了相同角色不同权限的动态分配,增强了购物网站中资源的安全性和可靠性。

  8. Novel modeling of task versus rest brain state predictability using a dynamic time warping spectrum: comparisons and contrasts with other standard measures of brain dynamics

    Directory of Open Access Journals (Sweden)

    Martin eDinov

    2016-05-01

    Full Text Available Dynamic time warping, or DTW, is a powerful and domain-general sequence alignment method for computing a similarity measure. Such dynamic programming-based techniques like DTW are now the backbone and driver of most bioinformatics methods and discoveries. In neuroscience it has had far less use, though this has begun to change. We wanted to explore new ways of applying DTW, not simply as a measure with which to cluster or compare similarity between features but in a conceptually different way. We have used DTW to provide a more interpretable spectral description of the data, compared to standard approaches such as the Fourier and related transforms. The DTW approach and standard discrete Fourier transform (DFT are assessed against benchmark measures of neural dynamics. These include EEG microstates, EEG avalanches and the sum squared error (SSE from a multilayer perceptron (MLP prediction of the EEG timeseries, and simultaneously acquired FMRI BOLD signal. We explored the relationships between these variables of interest in an EEG-FMRI dataset acquired during a standard cognitive task, which allowed us to explore how DTW differentially performs in different task settings. We found that despite strong correlations between DTW and DFT-spectra, DTW was a better predictor for almost every measure of brain dynamics. Using these DTW measures, we show that predictability is almost always higher in task than in rest states, which is consistent to other theoretical and empirical findings, providing additional evidence for the utility of the DTW approach.

  9. Dynamics of extended-spectrum cephalosporin resistance in pathogenic Escherichia coli isolated from diseased pigs in Quebec, Canada.

    Science.gov (United States)

    Jahanbakhsh, Seyedehameneh; Smith, Matthew G; Kohan-Ghadr, Hamid-Reza; Letellier, Ann; Abraham, Sam; Trott, Darren J; Fairbrother, John Morris

    2016-08-01

    The aim of this study was to investigate the evolution with time of ceftiofur-resistant Escherichia coli clinical isolates from pigs in Québec, Canada, between 1997 and 2012 with respect to pathotypes, clones and antimicrobial resistance. Eighty-five ceftiofur-resistant E. coli isolates were obtained from the OIE (World Organisation for Animal Health) Reference Laboratory for Escherichia coli. The most prevalent pathovirotypes were enterotoxigenic E. coli (ETEC):F4 (40%), extraintestinal pathogenic E. coli (ExPEC) (16.5%) and Shiga toxin-producing E. coli (STEC):F18 (8.2%). Susceptibility testing to 15 antimicrobial agents revealed a high prevalence of resistance to 13 antimicrobials, with all isolates being multidrug-resistant. blaCMY-2 (96.5%) was the most frequently detected β-lactamase gene, followed by blaTEM (49.4%) and blaCTX-M (3.5%). Pulsed-field gel electrophoresis (PFGE) applied to 45 representative E. coli isolates revealed that resistance to ceftiofur is spread both horizontally and clonally. In addition, the emergence of extended-spectrum β-lactamase-producing E. coli isolates carrying blaCTX-M was observed in 2011 and 2012 in distinct clones. The most predominant plasmid incompatibility (Inc) groups were IncFIB, IncI1, IncA/C and IncFIC. Resistance to gentamicin, kanamycin and chloramphenicol as well as the frequency of blaTEM and IncA/C significantly decreased over the study period, whereas the frequency of IncI1 and multidrug resistance to seven antimicrobial categories significantly increased. These findings reveal that extended-spectrum cephalosporin-resistant porcine E. coli isolates in Québec belong to several different clones with diverse antimicrobial resistance patterns and plasmids. Furthermore, blaCMY-2 was the major β-lactamase gene in these isolates. From 2011, we report the emergence of blaCTX-M in distinct clones.

  10. A Preliminary, Full Spectrum, Magnetic Anomaly Grid of the United States with Improved Long Wavelengths for Studying Continental Dynamics

    Science.gov (United States)

    Ravat, Dhananjay; Korhonen, Juha

    2010-05-01

    Under an initiative started by Thomas G. Hildenbrand of the U.S. Geological Survey, we have improved the long-wavelength (50-2,500 km) content of the regional magnetic anomaly compilation for the conterminous United States by utilizing a nearly homogeneous set of National Uranium Resource Evaluation (NURE) magnetic surveys flown from 1975 to 1981. The surveys were flown in quadrangles of 2° of longitude by 1° of latitude with east-west flight lines spaced 4.8 to 9.6 km apart, north-south tie lines variably spaced, and a nominal terrain clearance of 122 m. The NURE surveys were processed using the Comprehensive Magnetic Field Model (Sabaka et al. 2004) to remove the core field for the epochs of the surveys. Many of the surveys used base-station magnetometers to remove external field variations. This NURE magnetic anomaly field is merged with the short-wavelengths from the North American Magnetic Anomaly Map (ca. 2002) to create a full spectrum database called NURE_NAMAM2008. http://pubs.usgs.gov/of/2009/1258/

  11. The temporal dynamics of coherent motion processing in autism spectrum disorder: evidence for a deficit in the dorsal pathway.

    Science.gov (United States)

    Greimel, E; Bartling, J; Dunkel, J; Brückl, M; Deimel, W; Remschmidt, H; Kamp-Becker, I; Schulte-Körne, G

    2013-08-15

    Individuals with autism spectrum disorder (ASD) show impairments in processing coherent motion which have been proposed to be linked to a general deficit in the dorsal visual pathway. However, few studies have investigated the neural mechanisms underlying coherent motion processing in ASD. Thus, the aim of this study was to further test the hypothesis of a dorsal pathway deficit in ASD using visual evoked potentials (VEPs). 16 children and adolescents with ASD and 12 typically developing controls were examined with VEPs elicited by a random dot kinematogram. After an initial experimental sequence, where subjects were presented randomly moving dots, a fraction of the dots moved coherently (dependent on the level of coherence, 20%, 40%, or 60% of the dots) to the left or right side. Subjects were asked to detect the direction of coherent motion via button press. On the behavioural level, no significant group differences emerged. On the neural level, coherently moving dots elicited a N200 followed by a late positive potential (P400). ASD subjects exhibited a reduced N200 amplitude compared to controls. Moreover, in the ASD group, a trend for a negative relationship between N200 amplitude and a measure of autistic pathology was revealed. The present study provides strong support of a dorsal stream deficiency in the disorder and renders alternative explanations for impaired coherent motion processing in ASD less likely. Together with findings from related research fields, our data indicate that deviances in the N200 during coherent motion perception might be fundamental to ASD.

  12. Dissociation Dynamics of Nitrous Oxide from Jet-cooling Absorption Spectrum in 142.5-147.5 nm

    Institute of Scientific and Technical Information of China (English)

    Cheng Zhen; Ya-hua Hu; Xiao-guo Zhou; Shi-lin Liua

    2011-01-01

    The absorption spectrum of the C1Ⅱ state of N2O molecule in the wavelength range of 142.5-147.5 nm has been measured under the jet-cooled condition, and the clear spectral features are displayed. A vibrational progression is observed with a frequency interval of about 500 cm-1. With the aid of potential energy surfaces (PES) of the low-lying electronic states of N2O, the vibrational progression is assigned as the bending mode of the repulsive C1Ⅱ state. From the Fourier transfornation analysis, the recurrence period of the periodic orbit near the transition state region is derived to be 65 fs. Through the least-square Lorentzian fitting, the lifetimes of the resonance levels are estimated from their profile widths to be about 20 fs, which is shorter than the recurrence period. Therefore, a new explanation is suggested for the observed diffuse spectral structure, based on the behavior of dissociating N2O on PES of the C1Ⅱ state in the present excitation energy range.

  13. HIERARCHICAL ACCESS CONTROL IN DYNAMIC PEER GROUPS USING SYMMETRIC POLYNOMIAL AND TREE BASED GROUP ELLIPTIC CURVE DIFFIE HELLMAN SCHEME

    Directory of Open Access Journals (Sweden)

    Nafeesa Begum Jeddy

    2014-01-01

    Full Text Available Hierarchical Access Control in group communication is an active area of research which is difficult to achieve it. Its primary objective is to allow users of a higher authority group to access information or resource held by lower group users and preventing the lower group users to access information held by higher class users. Large collection of collaborative applications in organizations inherently has hierarchical structures for functioning, where providing security by efficient group key management is a big challenging issue. While preserving centralized methods for hierarchical access control, it is difficult to achieve efficiency as a single membership change will result in lot of changes which are difficult to maintain. So, using distributed key agreement techniques is more appropriate for this scenario. This study explore on novel group key agreement approach, which combines both the symmetric polynomial scheme and Tree Based Group elliptic Curve key exchange. Also, it yields a secure protocol suite that is good in fault-tolerant and simple. The efficiency of SP-TGECDH is better than many other schemes. Using TGECDH makes the scheme suitable small Low powered devices.

  14. Probing Lewis Acid-Base Interactions with Born-Oppenheimer Molecular Dynamics: The Electronic Absorption Spectrum of p-Nitroaniline in Supercritical CO2.

    Science.gov (United States)

    Cabral, Benedito J Costa; Rivelino, Roberto; Coutinho, Kaline; Canuto, Sylvio

    2015-07-02

    The structure and dynamics of p-nitroaniline (PNA) in supercritical CO2 (scCO2) at T = 315 K and ρ = 0.81 g cm(-3) are investigated by carrying out Born-Oppenheimer molecular dynamics, and the electronic absorption spectrum in scCO2 is determined by time dependent density functional theory. The structure of the PNA-scCO2 solution illustrates the role played by Lewis acid-base (LA-LB) interactions. In comparison with isolated PNA, the ν(N-O) symmetric and asymmetric stretching modes of PNA in scCO2 are red-shifted by -17 and -29 cm(-1), respectively. The maximum of the charge transfer (CT) absorption band of PNA in scSCO2 is at 3.9 eV, and the predicted red-shift of the π → π* electronic transition relative to the isolated gas-phase PNA molecule reproduces the experimental value of -0.35 eV. An analysis of the relationship between geometry distortions and excitation energies of PNA in scCO2 shows that the π → π* CT transition is very sensitive to changes of the N-O bond distance, strongly indicating a correlation between vibrational and electronic solvatochromism driven by LA-LB interactions. Despite the importance of LA-LB interactions to explain the solvation of PNA in scCO2, the red-shift of the CT band is mainly determined by electrostatic interactions.

  15. A Preliminary Full Spectrum Magnetic Anomaly Database of the United States With Improved Long Wavelengths for Studying Continental Dynamics

    Science.gov (United States)

    Ravat, D.; Sabaka, T.; Elshayat, A.; Aref, A.; Elawadi, E.; Kucks, R.; Hill, P.; Phillips, J.; Finn, C.; Bouligand, C.; Blakely, R. J.

    2008-12-01

    Under an initiative started by Thomas G. Hildenbrand of the U. S. Geological Survey, we have improved the long-wavelength (50-2500 km) content of the regional magnetic anomaly compilation for the conterminous United States by utilizing a nearly homogeneous set of National Uranium Resource Evaluation (NURE) magnetic surveys flown from 1975 to 1981. The surveys were flown in quadrangles of 2° of longitude by 1° of latitude with E-W flight-lines spaced 4.8 to 9.6 km, N-S tie-lines variably spaced, and a nominal terrain clearance of 122 m. Many of the surveys used base-station magnetometers to remove external field variations. NURE surveys were originally processed with IGRF core-field models, which left behind non- uniform residual trends in the data and discontinuities at survey boundaries. In this study, in place of the IGRF/DGRF, we used a spatially and temporally continuous model of the magnetic field known as the Comprehensive Model (CM), which allowed us to avoid discontinuities at survey boundaries. The CM simultaneously models the core magnetic field and long-wavelength ionospheric and magnetospheric fields, along with their induced components in the earth. Because of the availability of base-stations for removing external fields, we removed only the core-derived geomagnetic field based on CM4 (spherical harmonic degree 13) for our compilation. The NURE data have short-wavelength (less than 30 km) noise due to cultural sources, base-station offsets, and residual external field effects. It is possible to reduce and even remove these defects by identifying and editing them and by applying leveling and micro-leveling. There are also many high resolution individual surveys over the U.S. which could be incorporated into the improved NURE database; however, this could take a few years. Therefore, we have created a preliminary full spectrum magnetic anomaly database by combining short-wavelength magnetic anomalies from the North American Magnetic Anomaly Map (NAMAM

  16. Study on the applicability of frequency spectrum of micro-tremor and dynamic characteristics of surface ground in Asia area

    Institute of Scientific and Technical Information of China (English)

    CHE Ai-lan; IWATATE Takahiro; ODA Yoshiya; GE Xiu-run

    2006-01-01

    The dynamic characteristics of ground soil using micro-tremor observation in Asia (Zushi and Ogasawara (Japan),Xi'an (China), Manila (Philippines), and Gujarat (India)) are studied. Ground micro-tremor signals were observed and analyzed by fast Fourier transform method (FFT). The response of ground soil to frequency of ground micro-tremor is revealed, and functions with frequency-dependence and frequency-selection of micro-tremor for different foundation soil strata are also researched.The horizontal to vertical spectral ratio (H/V, Nakamura technique) of micro-tremor observed at the surface ground was used to evaluate the site's predominant period. This paper also discusses the application of micro-tremor on site safety evaluation, and gives the observed calculation results obtained at multiple points. The experimental foundation and the deduction process of the method are described in detail. Some problems of the method are pointed out. Potential use of the technique's good expandable nature makes it a useable means for preventing and reducing disaster's harmful effects.

  17. Establishing mass spectrum of $S=-1$ hyperon resonances via a dynamical coupled-channels analysis of $K^-p$ reactions

    CERN Document Server

    Kamano, Hiroyuki

    2016-01-01

    We report our recent effort for the extraction of resonance parameters (complex pole mass and residues etc.) associated with Lambda* and Sigma* hyperons. This was accomplished via a comprehensive partial-wave analysis of the data for K^- p --> barK N, pi Sigma, pi Lambda, eta Lambda, K Xi reactions from the thresholds up to W=2.1 GeV within a dynamical coupled-channels approach. The results suggest a possible existence of new narrow J^P=3/2^+ \\Lambda resonance with pole mass 1671^{+2}_{-8} -i(5^{+11}_{-2}) MeV, located close to the eta Lambda threshold. This resonance is found to be responsible for reproducing the data for K^-p --> eta Lambda differential cross sections near the threshold, and thus the data seem favor its existence. The extracted poles for J^P=1/2^- Lambda resonances below the barK N threshold, including Lambda(1405), are also presented.

  18. Carbon dioxide photolysis from 150 to 210 nm: Singlet and triplet channel dynamics, UV-spectrum, and isotope effects

    Science.gov (United States)

    Schmidt, Johan A.; Johnson, Matthew S.; Schinke, Reinhard

    2013-10-01

    We present a first principles study of the carbon dioxide (CO2) photodissociation process in the 150- to 210-nm wavelength range, with emphasis on photolysis below the carbon monoxide + singlet channel threshold at ∼167 nm. The calculations reproduce experimental absorption cross-sections at a resolution of ∼0.5 nm without scaling the intensity. The observed structure in the 150- to 210-nm range is caused by excitation of bending motion supported by the deep wells at bent geometries in the and potential energy surfaces. Predissociation below the singlet channel threshold occurs via spin-orbit coupling to nearby repulsive triplet states. Carbon monoxide vibrational and rotational state distributions in the singlet channel as well as the triplet channel for excitation at 157 nm satisfactorily reproduce experimental data. The cross-sections of individual CO2 isotopologues (12C16O2, 12C17O16O, 12C18O16O, 13C16O2, and 13C18O16O) are calculated, demonstrating that strong isotopic fractionation will occur as a function of wavelength. The calculations provide accurate, detailed insight into CO2 photoabsorption and dissociation dynamics, and greatly extend knowledge of the temperature dependence of the cross-section to cover the range from 0 to 400 K that is useful for calculations of propagation of stellar light in planetary atmospheres. The model is also relevant for the interpretation of laboratory experiments on mass-independent isotopic fractionation. Finally, the model shows that the mass-independent fractionation observed in a series of Hg lamp experiments is not a result of hyperfine interactions making predissociation of 17O containing CO2 more efficient.

  19. A 13µW 87dB dynamic range implantable ΔΣ modulator for full-spectrum neural recording.

    Science.gov (United States)

    Xu, Jian; Islam, Md Kafiul; Wang, Shuo; Yang, Zhi

    2013-01-01

    Experiment analysis on in-vivo data sequences suggests a wide system dynamic range (DR) is required to simultaneously record local field potentials (LFPs), extra-cellular spikes, and artifacts/interferences. In this paper, we present a 13 µW 87 dB DR ΔΣ modulator for full-spectrum neural recording. To achieve a wide DR and low power consumption, a fully-differential topology is used with multi-bit (MB) quantization scheme and switched-opamp (SO) technique. By adopting a novel fully-clocked scheme, a power-efficient current-mirror SO is developed with 50% power saving, which doubles the figure-of-merit (FOM) over its counterpart. A new static power-less multi-bit quantizer with 96% power and 69% area reduction is also introduced. Besides, instead of metal-insulator-metal (MIM) capacitor, three high-density MOS capacitor (MOSCAP) structures are employed to reduce circuit area. Measurement results show a peak signal-to-noise and distortion ratio (SNDR) of 85 dB with 10 kHz bandwidth at 1.0 V supply, corresponding to an FOM of 45 fJ/conv.-step. which is implemented in a 0.18 µm CMOS.

  20. Quantum dynamics on a three-sheeted six-dimensional ab initio potential-energy surface of the phosphine cation: Simulation of the photoelectron spectrum and the ultrafast radiationless decay dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, Swarnendu, E-mail: swarnendu.bhattacharyya@ch.tum.de; Domcke, Wolfgang, E-mail: wolfgang.domcke@ch.tum.de [Department of Chemistry, Technische Universität München, D-85748, Garching (Germany); Dai, Zuyang [Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China)

    2015-11-21

    A diabatic three-sheeted six-dimensional potential-energy surface has been constructed for the ground state and the lowest excited state of the PH{sub 3}{sup +} cation. Coupling terms of Jahn-Teller and pseudo-Jahn-Teller origin up to eighth order had to be included to describe the pronounced anharmonicity of the surface due to multiple conical intersections. The parameters of the diabatic Hamiltonian have been optimized by fitting the eigenvalues of the potential-energy matrix to ab initio data calculated at the CASSCF/MRCI level employing the correlation-consistent triple-ζ basis. The theoretical photoelectron spectrum of phosphine and the non-adiabatic nuclear dynamics of the phosphine cation have been computed by propagating nuclear wave packets with the multiconfiguration time-dependent Hartree method. The theoretical photoelectron bands obtained by Fourier transformation of the autocorrelation function agree well with the experimental results. It is shown that the ultrafast non-radiative decay dynamics of the first excited state of PH{sub 3}{sup +} is dominated by the exceptionally strong Jahn-Teller coupling of the asymmetric bending vibrational mode together with a hyperline of conical intersections with the electronic ground state induced by the umbrella mode. Time-dependent population probabilities have been computed for the three adiabatic electronic states. The non-adiabatic Jahn-Teller dynamics within the excited state takes place within ≈5 fs. Almost 80% of the excited-state population decay to the ground state within about 10 fs. The wave packets become highly complex and delocalized after 20 fs and no further significant transfer of electronic population seems to occur up to 100 fs propagation time.

  1. Low leakage Ru-strontium titanate-Ru metal-insulator-metal capacitors for sub-20 nm technology node in dynamic random access memory

    Energy Technology Data Exchange (ETDEWEB)

    Popovici, M., E-mail: Mihaela.Ioana.Popovici@imec.be; Swerts, J.; Redolfi, A.; Kaczer, B.; Aoulaiche, M.; Radu, I.; Clima, S.; Everaert, J.-L.; Van Elshocht, S.; Jurczak, M. [Imec, Leuven 3001 (Belgium)

    2014-02-24

    Improved metal-insulator-metal capacitor (MIMCAP) stacks with strontium titanate (STO) as dielectric sandwiched between Ru as top and bottom electrode are shown. The Ru/STO/Ru stack demonstrates clearly its potential to reach sub-20 nm technology nodes for dynamic random access memory. Downscaling of the equivalent oxide thickness, leakage current density (J{sub g}) of the MIMCAPs, and physical thickness of the STO have been realized by control of the Sr/Ti ratio and grain size using a heterogeneous TiO{sub 2}/STO based nanolaminate stack deposition and a two-step crystallization anneal. Replacement of TiN with Ru as both top and bottom electrodes reduces the amount of electrically active defects and is essential to achieve a low leakage current in the MIM capacitor.

  2. Mobility Management of VHF Dynamic Access in Low-altitude Airspace%低空空域VHF动态接入移动性管理

    Institute of Scientific and Technical Information of China (English)

    严雯

    2014-01-01

    The mobility management of Very High Frequency(VHF) dynamic access in low-altitude air-space is the key to realize uninterrupted and cross regional communication for low attitude flight. According to the low-altitude airspace communication network architecture,a hierarchical mobility management model is designed by Home Location Register/Visitor Location Register ( HLR/VLR ) mechanism with the suc-cessful experiences of Global System for Mobile( GSM) ,which dresses the issue of aircrafts location man-agement effectively. Registration,logging in/out,inter and intra station mobility management are described in detail. Finally,the delay of mobility management is analyzed and simulation is demonstrated,which lays foundation for further research on mobility management of VHF dynamic access.%低空空域超短波( VHF)动态接入移动性管理技术是保障低空飞行不间断、跨区域通信的关键。根据低空空管通信网络框架,设计了低空空管二级移动性管理模型;借鉴GSM经典移动性管理模型,引入访问/归属位置寄存器机制,解决了地面通信网有效管理低空飞行器位置信息的问题。详细阐述了登记注册、入网/退网、站内移动性管理和站间移动性管理等流程。最后,分析了移动性管理时延,并给出了系统演示和仿真,为进一步研究打下了基础。

  3. Target Channel Visiting Order Design Using Particle Swarm Optimization for Spectrum Handoff in Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Shilian Zheng

    2014-08-01

    Full Text Available In a dynamic spectrum access network, when a primary user (licensed user reappears on the current channel, cognitive radios (CRs need to vacate the channel and reestablish a communications link on some other channel to avoid interference to primary users, resulting in spectrum handoff. This paper studies the problem of designing target channel visiting order for spectrum handoff to minimize expected spectrum handoff delay. A particle swarm optimization (PSO based algorithm is proposed to solve the problem. Simulation results show that the proposed algorithm performs far better than random target channel visiting scheme. The solutions obtained by PSO are very close to the optimal solution which further validates the effectiveness of the proposed method.

  4. Dynamic Resource Allocation with Integrated Reinforcement Learning for a D2D-Enabled LTE-A Network with Access to Unlicensed Band

    Directory of Open Access Journals (Sweden)

    Alia Asheralieva

    2016-01-01

    Full Text Available We propose a dynamic resource allocation algorithm for device-to-device (D2D communication underlying a Long Term Evolution Advanced (LTE-A network with reinforcement learning (RL applied for unlicensed channel allocation. In a considered system, the inband and outband resources are assigned by the LTE evolved NodeB (eNB to different device pairs to maximize the network utility subject to the target signal-to-interference-and-noise ratio (SINR constraints. Because of the absence of an established control link between the unlicensed and cellular radio interfaces, the eNB cannot acquire any information about the quality and availability of unlicensed channels. As a result, a considered problem becomes a stochastic optimization problem that can be dealt with by deploying a learning theory (to estimate the random unlicensed channel environment. Consequently, we formulate the outband D2D access as a dynamic single-player game in which the player (eNB estimates its possible strategy and expected utility for all of its actions based only on its own local observations using a joint utility and strategy estimation based reinforcement learning (JUSTE-RL with regret algorithm. A proposed approach for resource allocation demonstrates near-optimal performance after a small number of RL iterations and surpasses the other comparable methods in terms of energy efficiency and throughput maximization.

  5. Unified equation for access to rate constants of first-order reactions in dynamic and on-column reaction chromatography.

    Science.gov (United States)

    Trapp, O

    2006-01-01

    A unified equation to evaluate elution profiles of reversible as well as irreversible (pseudo-) first-order reactions in dynamic chromatography and on-column reaction chromatography has been derived. Rate constants k1 and k(-1) and Gibbs activation energies are directly obtained from the chromatographic parameters (retention times tR(A) and tR(B) of the interconverting or reacting species A and B, the peak widths at half-height wA and wB, and the relative plateau height h(p)), the initial amounts A0 and B0 of the reacting species, and the equilibrium constant K(A/B). The calculation of rate constants requires only a few iterative steps without the need of performing a computationally extensive simulation of elution profiles. The unified equation was validated by comparison with a data set of 125,000 simulated elution profiles to confirm the quality of this equation by statistical means and to predict the minimal experimental requirements. Surprisingly, the recovery rate from a defined data set is on average 35% higher using the unified equation compared to the evaluation by iterative computer simulation.

  6. Zellweger Spectrum

    Science.gov (United States)

    ... severe defect, resulting in essentially nonfunctional peroxisomes. This phenomenon produces the range of severity of the disorders. How is the Zellweger Spectrum Diagnosed? The distinctive shape of the head and face of a child born with one of the diseases of the ...

  7. 认知网络中基于快速多赢家多频段拍卖的动态频谱分配%Dynamic spectrum assignment based on FADM algorithm in cognitive networks

    Institute of Scientific and Technical Information of China (English)

    吴广恩; 任品毅; 战明浩

    2009-01-01

    In order to improve auction effectiveness in dynamic spectrum assignment (DSA), a new assignment scheme based on FADM(fast auction with multiple goods and multiple winners) algorithm was given. The FADM algorithm transforms the traditional multiple goods auction into an integer 0/1 knapsack problem, whereby the optimal clearing vector can be found with dynamic programming. Our scheme restrains collusion with reservation price and discriminated price. Furthermore, the reservation price and bid price can be adjusted dynamically to spectrum supply and demand,which can balance revenue and social efficiency of spectrum auction. The results of performance analysis and simulation indicate that the FADM algorithm can make spectrum utilization close to demand and improve allocation revenue as high as possible.%针对传统拍卖方法在动态频谱分配中的低效问题,本文提出了一种基于FADM(fast auction with multiple bands and multiple winners)算法的动态频谱分配方法.FADM算法将传统的多物品拍卖问题转化为整数型0/1背包问题,从而可用动态规划寻求最佳的出清向量;新算法采用了保留价格和差异定价抑制共谋,且根据供求关系动态调整保留价格和竞标价格,兼顾了频谱分配的经济效益和社会效益.性能分析和计算机仿真结果表明,FADM算法可以使频谱有效利用率逼近实际需求率,同时尽可能提高分配收益.

  8. Automated Image Intelligence Adaptive Sensor Management System for High Altitude Long Endurance UAVs in a Dynamic and Anti-Access Area Denial Environment

    Science.gov (United States)

    Kim, Gi Young

    The problem we investigate deals with an Image Intelligence (IMINT) sensor allocation schedule for High Altitude Long Endurance UAVs in a dynamic and Anti-Access Area Denial (A2AD) environment. The objective is to maximize the Situational Awareness (SA) of decision makers. The value of SA can be improved in two different ways. First, if a sensor allocated to an Areas of Interest (AOI) detects target activity, then the SA value will be increased. Second, the SA value increases if an AOI is monitored for a certain period of time, regardless of target detections. These values are functions of the sensor allocation time, sensor type and mode. Relatively few studies in the archival literature have been devoted to an analytic, detailed explanation of the target detection process, and AOI monitoring value dynamics. These two values are the fundamental criteria used to choose the most judicious sensor allocation schedule. This research presents mathematical expressions for target detection processes, and shows the monitoring value dynamics. Furthermore, the dynamics of target detection is the result of combined processes between belligerent behavior (target activity) and friendly behavior (sensor allocation). We investigate these combined processes and derive mathematical expressions for simplified cases. These closed form mathematical models can be used for Measures of Effectiveness (MOEs), i.e., target activity detection to evaluate sensor allocation schedules. We also verify these models with discrete event simulations which can also be used to describe more complex systems. We introduce several methodologies to achieve a judicious sensor allocation schedule focusing on the AOI monitoring value. The first methodology is a discrete time integer programming model which provides an optimal solution but is impractical for real world scenarios due to its computation time. Thus, it is necessary to trade off the quality of solution with computation time. The Myopic Greedy

  9. Cognitive Self-Scheduled Mechanism for Access Control in Noisy Vehicular Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Mario Manzano

    2015-01-01

    Full Text Available Within the challenging environment of intelligent transportation systems (ITS, networked control systems such as platooning guidance of autonomous vehicles require innovative mechanisms to provide real-time communications. Although several proposals are currently under discussion, the design of a rapid, efficient, flexible, and reliable medium access control mechanism which meets the specific constraints of such real-time communications applications remains unsolved in this highly dynamic environment. However, cognitive radio (CR combines the capacity to sense the radio spectrum with the flexibility to adapt to transmission parameters in order to maximize system performance and has thus become an effective approach for the design of dynamic spectrum access (DSA mechanisms. This paper presents the enhanced noncooperative cognitive division multiple access (ENCCMA proposal combining time division multiple access (TDMA and frequency division multiple access (FDMA schemes with CR techniques to obtain a mechanism fulfilling the requirements of real-time communications. The analysis presented here considers the IEEE WAVE and 802.11p as reference standards; however, the proposed medium access control (MAC mechanism can be adapted to operate on the physical layer of different standards. The mechanism also offers the advantage of avoiding signaling, thus enhancing system autonomy as well as behavior in adverse scenarios.

  10. Open access

    NARCIS (Netherlands)

    Valkenburg, P.M.

    2015-01-01

    Open access week Van 19 tot en met 25 oktober 2015 vond wereldwijd de Open Access Week plaats. Tijdens deze week werden er over de hele wereld evenementen georganiseerd waar open access een rol speelt. Ook in Nederland zijn er diverse symposia, workshops en debatten georganiseerd zoals het debat in

  11. 基于TRBAC混合模型的协同设计过程动态访问控制%Dynamic access control of collaborative design process based on TRBAC hybrid model

    Institute of Scientific and Technical Information of China (English)

    郭银章; 曾建潮

    2012-01-01

    Aiming at the access control problem of collaborative design process which included access control lifecycle constraint, access control number constraint and dynamic changes features, the Role-Based Access Control (RBAC) model and Task- Based Access Control (TBAC) model were extended and incorporated. At the same time, a CDACM model for dynamic access control in collaborative design was proposed. To realized context-sensitive subject and object dynamic authorization management, authorization state migration and access control constraint were controlled by introducing the state migration and constraint relation of design unit authorization structure. The problems of access time constraint and transaction integrity constraint were solved by setting the constraints of permission ac- tivating cycle time and permission access times. Moreover, access control policy and activation mechanism for collaborative design were given. The theoretical research was applied in the collaborative design access control system of chain-transportation, which tested the validity of the proposed model.%针对具有周期时间约束、访问次数限制和设计过程动态变化特点的协同设计过程访问控制问题,将基于角色的访问控制模型和基于任务的访问控制模型进行扩展与融合,提出一种适应于协同设计全过程的动态访问控制模型CDACM。通过引入设计单元结构体的状态迁移和约束依赖关系,控制访问授权状态的变化和权限的约束,以实现与上下文相关的主客体动态授权管理;同时通过设定权限激活周期时间约束和权限访问次数限制约束,来解决权限访问时间限制和事务完整性约束问题。给出协同设计的访问控制策略和激活机制。将理论研究应用于链式输送机协同设计访问控制系统中,验证了所提模型的有效性。

  12. 船舶动力定位海浪环境的实时仿真与海浪谱分析%Real-time Simulation and Spectrum-Analisis of a Dynamic Positioning System Ship in Waves

    Institute of Scientific and Technical Information of China (English)

    王立军; 陈锋; 丁福光; 施小成

    2001-01-01

    提出一种根据随机海浪频谱来实时模拟随机海浪的方法,它可以用于研究动力定位船舶及其 控制系统在不同海况时的性能。该方法可以采用多种海浪谱来进行随机海浪的仿真。仿真结果利用了 快速傅立叶变换FFT(Fast Fourier Transform)进行频谱分析。仿真程序可用于实际的动力定位船舶系 统。%Provides a way to simulate waves in real-time according to random-wave-spectrum. It can be used to study the performances of dynamic positioning ship and control system under different waves. This method adapts several kinds of wave-spectrum to simulate waves. The results of simulation apply FFT(Fast Fourier Transform) to analyse the spectrum. The program has been applied to DPS (Dynamic Positioning System) ships.

  13. True CMB Power Spectrum Estimation

    CERN Document Server

    Paykari, P; Fadili, M J

    2012-01-01

    The cosmic microwave background (CMB) power spectrum is a powerful cosmological probe as it entails almost all the statistical information of the CMB perturbations. Having access to only one sky, the CMB power spectrum measured by our experiments is only a realization of the true underlying angular power spectrum. In this paper we aim to recover the true underlying CMB power spectrum from the one realization that we have without a need to know the cosmological parameters. The sparsity of the CMB power spectrum is first investigated in two dictionaries; Discrete Cosine Transform (DCT) and Wavelet Transform (WT). The CMB power spectrum can be recovered with only a few percentage of the coefficients in both of these dictionaries and hence is very compressible in these dictionaries. We study the performance of these dictionaries in smoothing a set of simulated power spectra. Based on this, we develop a technique that estimates the true underlying CMB power spectrum from data, i.e. without a need to know the cosmo...

  14. Spread spectrum image steganography.

    Science.gov (United States)

    Marvel, L M; Boncelet, C R; Retter, C T

    1999-01-01

    In this paper, we present a new method of digital steganography, entitled spread spectrum image steganography (SSIS). Steganography, which means "covered writing" in Greek, is the science of communicating in a hidden manner. Following a discussion of steganographic communication theory and review of existing techniques, the new method, SSIS, is introduced. This system hides and recovers a message of substantial length within digital imagery while maintaining the original image size and dynamic range. The hidden message can be recovered using appropriate keys without any knowledge of the original image. Image restoration, error-control coding, and techniques similar to spread spectrum are described, and the performance of the system is illustrated. A message embedded by this method can be in the form of text, imagery, or any other digital signal. Applications for such a data-hiding scheme include in-band captioning, covert communication, image tamperproofing, authentication, embedded control, and revision tracking.

  15. Dynamic spectrum allocation based on one-band multi-winner auction%基于单频段多赢家拍卖的动态频谱分配

    Institute of Scientific and Technical Information of China (English)

    张文柱; 王凌云

    2012-01-01

    针对传统拍卖方法在认知无线网络动态频谱分配中的低效问题,提出了一种基于单频段多赢家拍卖的动态频谱分配算法.该算法在原始贪婪算法的基础上增加了多重贪婪策略,以较低的计算复杂度获得了较优的解;改进了VCG(vickery-clarke-groves)机制,在保留占优策略激励兼容特性的基础上,提高了卖家的收益,有效抑制共谋的发生.仿真结果表明,该算法的频谱分配效率接近最优分配效率,同时提高了拍卖的经济收益.%In order to improve the effectiveness of traditional auction in DSA (dynamic spectrum allocation) issue in cognitive radio networks, a new dynamic spectrum allocation algorithm based on one-band multi-winner auction was proposed. Compared with the original greedy algorithm, the new algorithm can achieve better spectrum allocation solutions with lower computational complexity by introducing the multiple greedy strategy. It increases the seller's revenue by improving the VCG (vickery-clarke-groves) mechanism, while retaining the dominant strategy incentive compatible property. In addition, it suppresses the occurrence of collusion effectively. Simulation results show that the algorithm proposed can get spectrum allocation efficiency close to the optimal solution and increase the auction revenue significantly.

  16. Relationship between the Integrated Intensity of the Power Spectrum of Scattered Light and Tissue Blood Volume by the Dynamic Light Scattering Method

    Science.gov (United States)

    Kashima, Susumu; Nishihara, Minoru; Takemoto, Yoshihiro; Osawa, Toshihiko

    1990-09-01

    The laser scattering characteristics from tissue microvasculature have been made clear by means of theoretical and experimental approaches. Our results show that the integrated intensity of the power spectrum correlates linearly with the volume of red blood cells in a given tissue provided the average collision number (\\bar{m}) between photons and moving red blood cells is less than unity. Also, the integrated intensity of the power spectrum is proportional to tissue blood volume if the density of red blood cells in blood (hematocrit) is constant.

  17. Fission Spectrum

    Science.gov (United States)

    Bloch, F.; Staub, H.

    1943-08-18

    Measurements of the spectrum of the fission neutrons of 25 are described, in which the energy of the neutrons is determined from the ionization produced by individual hydrogen recoils. The slow neutrons producing fission are obtained by slowing down the fast neutrons from the Be-D reaction of the Stanford cyclotron. In order to distinguish between fission neutrons and the remaining fast cyclotron neutrons both the cyclotron current and the pusle amplifier are modulated. A hollow neutron container, in which slow neutrons have a lifetime of about 2 milliseconds, avoids the use of large distances. This method results in much higher intensities than the usual modulation arrangement. The results show a continuous distribution of neutrons with a rather wide maximum at about 0.8 MV falling off to half of its maximum value at 2.0 MV. The total number of netrons is determined by comparison with the number of fission fragments. The result seems to indicate that only about 30% of the neutrons have energies below .8 MV. Various tests are described which were performed in order to rule out modification of the spectrum by inelastic scattering. Decl. May 4, 1951

  18. 基于预售机制的动态频谱分配算法研究%Research on game-based dynamic spectrum management in preselling mechanism

    Institute of Scientific and Technical Information of China (English)

    刘觉夫; 陈晓

    2013-01-01

    在认知无线网络环境下,为高效合理地进行频谱资源的管理与分配,引入经济活动中的预售机制,提出了基于预售机制的动态频谱管理(PS-DSM)方案.针对方案频谱市场分级架构及运作流程进行详细阐述,对方案中基础市场(BM)频谱分配细节进行了基于超模博弈方法的分析与仿真,实验结果表明,该方案能有效的减少时延,加快收敛速度,提高频谱利用效率.%With the rapid development of wireless communication technologies, the contradiction between spectrum supply and demand has become increasingly serious, In the cognitive radio network environment, to manage and allocate the efficient spectrum, the preselling mechanism in economic activity is introduced and game-based dynamic spectrum management in preselling mechanism (PS-DSM) are proposed Then the framework of the PS-DSM and its work flow are elaborated in details, then basic market (BM) spectrum allocation details is illustrated in supermodel game-theory analysis and simulatioa Simulations show that the PS-DSM program can not only reduce the delay, accelerate the convergence rate, but also improve the spectrum utilization efficiency.

  19. Expanding the phenotypic spectrum of ARID1B-mediated disorders and identification of altered cell-cycle dynamics due to ARID1B haploinsufficiency

    DEFF Research Database (Denmark)

    Sim, J. C. H.; White, S. M.; Fitzpatrick, E.

    2014-01-01

    or nonsense mutations in all of them. Conclusions: This study broadens the spectrum of ARID1B associated phenotypes by describing a distinctive phenotype including plantar fat pads but lacking the hypertrichosis or fifth nail hypoplasia associated with Coffin-Siris syndrome. We present the first direct...

  20. Intervening in global markets to improve access to HIV/AIDS treatment: an analysis of international policies and the dynamics of global antiretroviral medicines markets

    Directory of Open Access Journals (Sweden)

    Hochstadt Jenny

    2010-05-01

    Full Text Available Abstract Background Universal access to antiretroviral therapy (ART in low- and middle-income countries faces numerous challenges: increasing numbers of people needing ART, new guidelines recommending more expensive antiretroviral (ARV medicines, limited financing, and few fixed-dose combination (FDC products. Global initiatives aim to promote efficient global ARV markets, yet little is known about market dynamics and the impact of global policy interventions. Methods We utilize several data sources, including 12,958 donor-funded, adult first-line ARV purchase transactions, to describe the market from 2002-2008. We examine relationships between market trends and: World Health Organization (WHO HIV/AIDS treatment guidelines; WHO Prequalification Programme (WHO Prequal and United States (US Food and Drug Administration (FDA approvals; and procurement policies of the Global Fund to Fight AIDS, Tuberculosis, and Malaria (GFATM, US President's Emergency Plan for AIDS Relief (PEPFAR and UNITAID. Results WHO recommended 7, 4, 24, and 6 first-line regimens in 2002, 2003, 2006 and 2009 guidelines, respectively. 2009 guidelines replaced a stavudine-based regimen ($88/person/year with more expensive zidovudine- ($154-260/person/year or tenofovir-based ($244-465/person/year regimens. Purchase volumes for ARVs newly-recommended in 2006 (emtricitabine, tenofovir increased >15-fold from 2006 to 2008. Twenty-four generic FDCs were quality-approved for older regimens but only four for newer regimens. Generic FDCs were available to GFATM recipients in 2004 but to PEPFAR recipients only after FDA approval in 2006. Price trends for single-component generic medicines mirrored generic FDC prices. Two large-scale purchasers, PEPFAR and UNITAID, together accounted for 53%, 84%, and 77% of market volume for abacavir, emtricitabine, and tenofovir, respectively, in 2008. PEPFAR and UNITAID purchases were often split across two manufacturers. Conclusions Global initiatives

  1. Dynamic event Tress applied to sequences Full Spectrum LOCA. Calculating the frequency of exceedance of damage by integrated Safety Analysis Methodology; Arboles de sucesos dinamicos aplicados a secuencias Full Spectrum LOCA. Calculo de la frequencia de excedencia del dano mediante la metodologia Analisis Integrados de Seguridad (ISA)

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Magan, J. J.; Fernandez, I.; Gil, J.; Marrao, H.; Queral, C.; Gonzalez-Cadelo, J.; Montero-Mayorga, J.; Rivas, J.; Ibane-Llano, C.; Izquierdo, J. M.; Sanchez-Perea, M.; Melendez, E.; Hortal, J.

    2013-09-01

    The Integrated Safety Analysis (ISA) methodology, developed by the Spanish Nuclear Safety council (CSN), has been applied to obtain the dynamic Event Trees (DETs) for full spectrum Loss of Coolant Accidents (LOCAs) of a Westinghouse 3-loop PWR plant. The purpose of this ISA application is to obtain the Damage Exceedance Frequency (DEF) for the LOCA Event Tree by taking into account the uncertainties in the break area and the operator actuation time needed to cool down and de pressurize reactor coolant system by means of steam generator. Simulations are performed with SCAIS, a software tool which includes a dynamic coupling with MAAP thermal hydraulic code. The results show the capability of the ISA methodology to obtain the DEF taking into account the time uncertainty in human actions. (Author)

  2. Access Denied

    Science.gov (United States)

    Villano, Matt

    2008-01-01

    Building access control (BAC)--a catchall phrase to describe the systems that control access to facilities across campus--has traditionally been handled with remarkably low-tech solutions: (1) manual locks; (2) electronic locks; and (3) ID cards with magnetic strips. Recent improvements have included smart cards and keyless solutions that make use…

  3. Open Access

    Science.gov (United States)

    Suber, Peter

    2012-01-01

    The Internet lets us share perfect copies of our work with a worldwide audience at virtually no cost. We take advantage of this revolutionary opportunity when we make our work "open access": digital, online, free of charge, and free of most copyright and licensing restrictions. Open access is made possible by the Internet and copyright-holder…

  4. Open Access

    Science.gov (United States)

    Suber, Peter

    2012-01-01

    The Internet lets us share perfect copies of our work with a worldwide audience at virtually no cost. We take advantage of this revolutionary opportunity when we make our work "open access": digital, online, free of charge, and free of most copyright and licensing restrictions. Open access is made possible by the Internet and copyright-holder…

  5. Manycast routing, modulation level and spectrum assignment over elastic optical networks

    Science.gov (United States)

    Luo, Xiao; Zhao, Yang; Chen, Xue; Wang, Lei; Zhang, Min; Zhang, Jie; Ji, Yuefeng; Wang, Huitao; Wang, Taili

    2017-07-01

    Manycast is a point to multi-point transmission framework that requires a subset of destination nodes successfully reached. It is particularly applicable for dealing with large amounts of data simultaneously in bandwidth-hungry, dynamic and cloud-based applications. As rapid increasing of traffics in these applications, the elastic optical networks (EONs) may be relied on to achieve high throughput manycast. In terms of finer spectrum granularity, the EONs could reach flexible accessing to network spectrum and efficient providing exact spectrum resource to demands. In this paper, we focus on the manycast routing, modulation level and spectrum assignment (MA-RMLSA) problem in EONs. Both EONs planning with static manycast traffic and EONs provisioning with dynamic manycast traffic are investigated. An integer linear programming (ILP) model is formulated to derive MA-RMLSA problem in static manycast scenario. Then corresponding heuristic algorithm called manycast routing, modulation level and spectrum assignment genetic algorithm (MA-RMLSA-GA) is proposed to adapt for both static and dynamic manycast scenarios. The MA-RMLSA-GA optimizes MA-RMLSA problem in destination nodes selection, routing light-tree constitution, modulation level allocation and spectrum resource assignment jointly, to achieve an effective improvement in network performance. Simulation results reveal that MA-RMLSA strategies offered by MA-RMLSA-GA have slightly disparity from the optimal solutions provided by ILP model in static scenario. Moreover, the results demonstrate that MA-RMLSA-GA realizes a highly efficient MA-RMLSA strategy with the lowest blocking probability in dynamic scenario compared with benchmark algorithms.

  6. 粘弹性阻尼材料动态力学性能温度谱模型%Temperature Spectrum Model of Dynamic Mechanical Properties for Viscoelastic Damping Materials

    Institute of Scientific and Technical Information of China (English)

    张针粒; 李世其; 朱文革

    2011-01-01

    粘弹性阻尼材料的动态力学性能通常以时温叠加得到的频率谱主曲线表征,而时温叠加过程需要测量多个温度下的频率谱,难以保证试验条件的一致性.为此,由时温叠加原理,提出频率谱—温度谱镜像关系的数学形式.基于频率谱五参数分数微分模型,提出粘弹性阻尼材料的动态力学性能温度谱六参数分数微分模型,简称温度谱模型.所提模型能直接利用动态机械分析的试验结果,对于损耗模量和损因子具有对称性或非对称性的情形均适用.温度谱模型的参数具有明确的物理含义,推导温度谱模型参数的初值公式,并给出参数辨识步骤.不同材料在不同测试条件下的动态机械分析试验表明,所提模型可较好地表征粘弹性阻尼材料动态力学性能随温度的变化.%The dynamic mechanical properties of viscoelastic damping materials are usually represented by the master curve (MC) in the frequency domain. In order to construct a MC, multiple frequency spectrums must be tested, in which case it's difficult to maintain the same test conditions. A mathematical form of the mirror relationship between the temperature spectrum and frequency spectrum is suggested according to the time-temperature superposition principle. Based on the five-parameter fractional derivative frequency spectrum model, a six-parameter fractional derivative temperature spectrum model of dynamic mechanical properties, temperature spectrum model for short, is established for viscoelastic damping materials. The proposed model can directly use the results of dynamic mechanical analysis (DMA), and is applicable whether the loss modulus and loss factor are symmetrical or asymmetrical. The six parameters in the model all have clear physical meanings, and some formulas are derived to obtain their initial values, which can be refined by the suggested parameter identification procedure. DMA tests using different materials under

  7. A Research on UCON Enhanced Dynamic Access Control Model for the Business Process of Composite Web Services%UCON支持的组合Web服务业务流程访问控制模型

    Institute of Scientific and Technical Information of China (English)

    上超望; 刘清堂; 赵呈领; 王艳凤; 杨琳

    2011-01-01

    Business process access control mechanism is a difficult problem in Web services composition application.The dynamic Interactivity and Coordination of business process activities have been ignored in the existing research,which can not meet the demands for the dynamic business process access control.An UCON enhanced business process dynamic access control model(WS-BPUCON) is proposed,which unbinds the coupling relationship of organization model and the process model,and provides sufficient flexibility to implement the dynamic and fine-gained access control based on the authorization,obligation and condition for business process.The paper also describes the implementation architecture of WS-BPUCON in the end.%业务流程访问控制机制是组合Web服务应用中的难点,现有的访问控制模型忽视了流程活动之间动态交互性和协同性的特点,不能适应业务流程权限的动态管理.本文提出一种使用控制支持的组合Web服务业务流程动态访问控制模型WS-BPUCON,模型通过角色和权限的分离解除了组织模型和业务流程模型的耦合关系,能够根据分布式开放网络环境中的属性信息,基于授权、职责和条件三种约束决定策略来检查访问控制决策,具有上下文感知、细粒度访问管理等特性,给出了WS-BPUCON的实施框架.

  8. Full dimensional (15-dimensional) quantum-dynamical simulation of the protonated water-dimer III: Mixed Jacobi-valence parametrization and benchmark results for the zero point energy, vibrationally excited states, and infrared spectrum.

    Science.gov (United States)

    Vendrell, Oriol; Brill, Michael; Gatti, Fabien; Lauvergnat, David; Meyer, Hans-Dieter

    2009-06-21

    Quantum dynamical calculations are reported for the zero point energy, several low-lying vibrational states, and the infrared spectrum of the H(5)O(2)(+) cation. The calculations are performed by the multiconfiguration time-dependent Hartree (MCTDH) method. A new vector parametrization based on a mixed Jacobi-valence description of the system is presented. With this parametrization the potential energy surface coupling is reduced with respect to a full Jacobi description, providing a better convergence of the n-mode representation of the potential. However, new coupling terms appear in the kinetic energy operator. These terms are derived and discussed. A mode-combination scheme based on six combined coordinates is used, and the representation of the 15-dimensional potential in terms of a six-combined mode cluster expansion including up to some 7-dimensional grids is discussed. A statistical analysis of the accuracy of the n-mode representation of the potential at all orders is performed. Benchmark, fully converged results are reported for the zero point energy, which lie within the statistical uncertainty of the reference diffusion Monte Carlo result for this system. Some low-lying vibrationally excited eigenstates are computed by block improved relaxation, illustrating the applicability of the approach to large systems. Benchmark calculations of the linear infrared spectrum are provided, and convergence with increasing size of the time-dependent basis and as a function of the order of the n-mode representation is studied. The calculations presented here make use of recent developments in the parallel version of the MCTDH code, which are briefly discussed. We also show that the infrared spectrum can be computed, to a very good approximation, within D(2d) symmetry, instead of the G(16) symmetry used before, in which the complete rotation of one water molecule with respect to the other is allowed, thus simplifying the dynamical problem.

  9. 基于集合竞价置换的双向动态频谱分配算法%Double Dynamic Spectrum Allocation Algorithm Based on Set Bid Permutation

    Institute of Scientific and Technical Information of China (English)

    刘觉夫; 胡静; 杨将; 朱丙虎

    2015-01-01

    Aiming at the problems of dynamic spectrum allocation in cognitive radio networks, by establishing bi-lateral market model, a double dynamic spectrum allocation algorithm based on set bid permutation is proposed. Taking the individual rationality of the participants into account, this algorithm abstracts the game between two parties of the auction as the game between cognitive users. In the process of the auction, each cognitive user bids independently, and the auctioneer then divides the cognitive users set and distributes the spectrum according to cognitive users set bids, the real payments and the winners of two parties. Simulation illustrates great improvement of transaction rate, revenue and preferable β-competitiveness.%针对认知无线网络中的动态频谱分配问题,引入双边市场模型,提出了基于集合竞价置换的双向动态频谱分配算法(SBPA,set bid permutation algorithm).该算法考虑认知用户的个体理性,将拍卖参与双方之间的博弈抽象为认知用户之间的博弈.在频谱拍卖过程中,每个认知用户独立竞价,代理商划分认知用户集合并根据认知用户的集合竞价、拍卖双方的真实出价以及拍卖双方的赢家对频谱进行分配.仿真结果表明,该算法能够显著地提高拍卖成交率和拍卖收益,并具有较优的β-竞争性.

  10. Spectrum Services 2007

    Science.gov (United States)

    Dobos, L.; Budavári, T.; Csabai, I.; Szalay, A. S.

    2008-10-01

    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-the-fly; galactic extinction correction, fitting of the continuum using different set of templates (Bruzual-Charlot '03 templates, SDSS eigenspectra), line fitting. All scientific functionalities are 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 functionalities 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

  11. A Bank Card Access Authentication System based on Mobile Dynamic Password%基于手机动态密码的银行卡接入认证系统

    Institute of Scientific and Technical Information of China (English)

    古明涛; 陈昌

    2011-01-01

    传统的银行卡接入认证采取"卡号+静态密码"的方式,由于密码固定,给不法分子提供了窃取用户个人存款的机会。文中提出了一种基于AES算法的动态密码生成机制,并根据此机制设计与实现了一个基于手机动态密码的银行卡接入认证系统。通过实验分析表明,提出的机制生成的动态密码重复率很低,实现了一次一密的动态登录,提高了银行卡接入的安全性。%Traditional bank card access authentication still adopts the way of "Card Number+Static Password". As the password is fixed,some lawbreakers would have the opportunities to steal personal savings. In this paper,a mechanism for generating dynamic password based on AES is proposed. According to this mechanism,a bank card access authentication system based on mobile dynamic password is designed and implemented. The experiment and analysis indicate that the repetition rate of dynamic password based on this mechanism is very low. One-time password is realized and the security of bank card access improved.

  12. 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...

  13. The Spectrum and Laplacian Spectrum of the Dice Lattice

    Science.gov (United States)

    Li, Shuli; Yan, Weigen; Tian, Tao

    2016-07-01

    The dice lattice is the dual lattice of kagomé lattice. Many physical properties on the dice lattice have been studied by physicists, such as Ising model, Glassy dynamics of Josephson arrays, and Lattice Green's function. In this paper, we derive the spectrum and Laplacian spectrum of the dice lattice with toroidal boundary condition. In addition, we apply our results to obtain the formulae of the number of spanning trees, the Kirchhoff index, and the energy of the dice lattice with toroidal boundary condition.

  14. Accessible Knowledge - Knowledge on Accessibility

    DEFF Research Database (Denmark)

    Kirkeby, Inge Mette

    2015-01-01

    Although serious efforts are made internationally and nationally, it is a slow process to make our physical environment accessible. In the actual design process, architects play a major role. But what kinds of knowledge, including research-based knowledge, do practicing architects make use of when...... designing accessible environments? The answer to the question is crucially important since it affects how knowledge is distributed and how accessibility can be ensured. In order to get first-hand knowledge about the design process and the sources from which they gain knowledge, 11 qualitative interviews...... were conducted with architects with experience of designing for accessibility. The analysis draws on two theoretical distinctions. The first is research-based knowledge versus knowledge used by architects. The second is context-independent knowledge versus context-dependent knowledge. The practitioners...

  15. Open access

    CERN Document Server

    Suber, Peter

    2012-01-01

    The Internet lets us share perfect copies of our work with a worldwide audience at virtually no cost. We take advantage of this revolutionary opportunity when we make our work "open access": digital, online, free of charge, and free of most copyright and licensing restrictions. Open access is made possible by the Internet and copyright-holder consent, and many authors, musicians, filmmakers, and other creators who depend on royalties are understandably unwilling to give their consent. But for 350 years, scholars have written peer-reviewed journal articles for impact, not for money, and are free to consent to open access without losing revenue. In this concise introduction, Peter Suber tells us what open access is and isn't, how it benefits authors and readers of research, how we pay for it, how it avoids copyright problems, how it has moved from the periphery to the mainstream, and what its future may hold. Distilling a decade of Suber's influential writing and thinking about open access, this is the indispe...

  16. Ultra-fast charge carrier dynamics across the spectrum of an optical gain media based on InAs/AlGaInAs/InP quantum dots

    Directory of Open Access Journals (Sweden)

    I. Khanonkin

    2017-03-01

    Full Text Available The charge carrier dynamics of improved InP-based InAs/AlGaInAs quantum dot (QD semiconductor optical amplifiers are examined employing the multi-wavelength ultrafast pump-probe measurement technique. The transient transmission response of the continuous wave probe shows interesting dynamical processes during the initial 2-3 ps after the pump pulse, when carriers originating from two photon absorption contribute the least to the recovery. The effects of optical excitations and electrical bias levels on the recovery dynamics of the gain in energetically different QDs are quantified and discussed. The experimental observations are validated qualitatively using a comprehensive finite-difference time-domain model by recording the time evolution of the charge carriers in the QDs ensemble following the pulse.

  17. Dynamics

    CERN Document Server

    Goodman, Lawrence E

    2001-01-01

    Beginning text presents complete theoretical treatment of mechanical model systems and deals with technological applications. Topics include introduction to calculus of vectors, particle motion, dynamics of particle systems and plane rigid bodies, technical applications in plane motions, theory of mechanical vibrations, and more. Exercises and answers appear in each chapter.

  18. Access French

    CERN Document Server

    Grosz, Bernard

    2014-01-01

    Access is the major new language series designed with the needs of today's generation of students firmly in mind. Whether learning for leisure or business purposes or working towards a curriculum qualification, Access French is specially designed for adults of all ages and gives students a thorough grounding in all the skills required to understand, speak, read and write contemporary French from scratch. The coursebook consists of 10 units covering different topic areas, each of which includes Language Focus panels explaining the structures covered and a comprehensive glossary. Learning tips

  19. Fault diagnosis approach of dynamic system based on data driven of nonlinear spectrum%基于非线性频谱数据驱动的动态系统故障诊断方法

    Institute of Scientific and Technical Information of China (English)

    张家良; 曹建福; 高峰; 韩海涛

    2014-01-01

    基于非线性频谱数据驱动方法,研究了动态系统的故障诊断问题。利用一维非线性输出频率响应函数提出一种非线性频谱特征提取方法,为了提高实时性,采用变步长自适应辨识算法进行求解;根据估计偏差实时地改变步长,兼顾了收敛速度与稳态误差;获取了非线性频谱特征之后,利用最小二乘支持向量机分类器进行故障识别。通过对提升设备的故障诊断问题进行实验研究,所得结果表明,所提出的算法识别率高,能满足在线诊断要求。%The problem of fault diagnosis for the dynamic system is studied based on the data driven method of nonlinear spectrum. An extraction method of nonlinear frequency spectrum feature is proposed by using one dimensional nonlinear output frequency response function. In order to improve timeliness, the variable step size adaptive identification algorithm is used to solve the nonlinear output frequency response function. The step size is changed according to estimating error so that convergence rate and steady state error are both considered. After obtained nonlinear frequency spectrum feature, the least square support vector machine classifier is used to fault identification. The fault diagnosis of hoisting equipment is researched, and experiments show that the proposed algorithm has the good high recognition rate that can fulfill the demand of online diagnosis.

  20. Hemodialysis access - self care

    Science.gov (United States)

    Kidney failure - chronic-hemodialysis access; Renal failure - chronic-hemodialysis access; Chronic renal insufficiency - hemodialysis access; Chronic kidney failure - hemodialysis access; Chronic renal failure - ...

  1. Agent-based dynamic spectrum trading algorithm in cognitive radio network%认知无线网络中基于代理的动态频谱交易算法

    Institute of Scientific and Technical Information of China (English)

    张士兵; 张国栋; 包志华

    2013-01-01

      为了提高认知无线网络中频谱共享所产生的效益,研究了认知网络的频谱管理技术,提出了一种基于代理的频谱交易算法。该方法以代理商作为频谱交易和分配的中介,减轻了多主用户、多次用户频谱交易过程中的系统开销;在各主用户服务提供商之间采取相互竞争或相互合作的模式以最大化自身利益或总体利益为目标与代理商达成最终的频谱交易价格和频谱出售量,代理商把交易得来的频谱在次用户之间进行拍卖,各次用户向代理商投标,代理商根据其投标分配相应的频谱,次用户自适应地调整投标以使自身利益最大化。主用户服务提供商之间的竞争或合作和次用户之间的竞拍均采用纳什均衡作为最终的结果。基于 MATLAB 对所提算法的性能进行了仿真,仿真结果验证了该算法的有效性。%In order to improve the benefits generated by spectrum sharing, the spectrum management was studied and the agent-based dynamic spectrum trading algorithm was proposed. In the algorithm, the agent was used as a medium for spectrum trading, which reduced the huge system overhead among multi-primary service providers (PSP) and mul-ti-secondary users (SU). All PSP competed or cooperated with each other to achieve the maximum self-profit or total profit respectively, and come to terms with the agents on the final transaction price and quantity of spectrum. And then, the agent auctioned the spectrum among all SU. Each SU submitted a bid to the agent, then the agent allocated corre-sponding spectrum quantity to the SU. All SU adaptively adjusted the bids to achieve the maximum self-profit. Nash equilibrium was considered as the solution to both the game among PSP and the auction among SU. Simulation results show that the proposed algorithm performs well.

  2. Spectrum and service pricing for 802.22 networks

    DEFF Research Database (Denmark)

    Stefan, Andrei Lucian; Rota, Cyril; Pratas, Nuno

    2011-01-01

    IEEE 802.22 standard is the first cognitive radio standard that targets the spectrum used by TV broadcasters. This has created a number of conflicts between mobile operators and TV operators, as the latter expects financial compensations from the entities accessing their spectrum. Thus, in the fi......IEEE 802.22 standard is the first cognitive radio standard that targets the spectrum used by TV broadcasters. This has created a number of conflicts between mobile operators and TV operators, as the latter expects financial compensations from the entities accessing their spectrum. Thus...

  3. Atomic positional disorder, phonon spectrum, and molecular-dynamics simulation of Tl2CaBa2Cu2O8 and Tl2Ca2Ba2Cu3O10

    Science.gov (United States)

    Chaplot, S. L.

    1992-03-01

    The nature of the atomic positional disorder in the high-temperature superconducting ceramic oxides Tl2CaBa2Cu2O8 (Tl 2:1:2:2) and Tl2Ca2Ba2Cu3O10 (Tl 2:2:2:3) is studied with the help of an ionic-type interatomic potential and molecular-dynamics computer simulations. The pair distribution function and the phonon spectrum are calculated using this model and compared with results of neutron-scattering experiments on Tl 2:1:2:2. Calculated results on the partial pair distribution function, partial phonon density of states, mean square atomic vibrational amplitudes, and lattice specific heat are also presented.

  4. A dynamic spectrum allocation algorithm based on repeated games in cognitive radio%基于多次博弈的认知无线电频谱动态分配算法

    Institute of Scientific and Technical Information of China (English)

    滕志军; 杨旭; 韩雪

    2012-01-01

    As cognitive radio network complexity and dynamic, by a single game is hard to find the best balance. This article proposed a dynamic spectrum allocation algorithm based on repeated games in cognitive radio networks. The uniqueness and existence of the Nash equilibrium was proved for the scheme. Simulation results show that the novel spectrum allocation algorithm based on game theory will be obtained better convergence compared with traditional algorithm, after about 4~6 iterations algorithm will converge to an NE and can satisfy the real-time requirement, the novel algorithm can regulate their transmitter powers to meet the different signal to interference ratio (SIR) requirements and the performance of CR system is thereby improved obviously.%针对认知无线电网络的复杂性以及动态性,通过单次博弈很难找到最佳平衡点的问题,提出了一种基于多次博弈的动态频谱分配算法,并通过博弈论的相关原理对该算法中纳什均衡的存在性和唯一性进行了验证.仿真结果表明,该算法收敛性优于传统算法,经过4~6次迭代即可收敛于稳定状态,不仅提高了收敛速度,满足了通信系统对实时性的要求,同时也能够在系统中所有认知用户都满足信于比阈值要求的基础上进一步降低发射功率,达到了降低系统总干扰水平的目标,系统性能明显提高.

  5. The Sun's Photospheric Convection Spectrum

    CERN Document Server

    Hathaway, David H; Norton, Aimee A; Kitiashvili, Irina

    2015-01-01

    Spectra of the cellular photospheric flows are determined from full-disk Doppler velocity observations acquired by the Helioseismic and Magnetic Imager (HMI) instrument on the Solar Dynamics Observatory (SDO) spacecraft. Three different analysis methods are used to separately determine spectral coefficients representing the poloidal flows, the toroidal flows, and the radial flows. The amplitudes of these spectral coefficients are constrained by simulated data analyzed with the same procedures as the HMI data. We find that the total velocity spectrum rises smoothly to a peak at a wavenumber of about 120 (wavelength of about 35 Mm), which is typical of supergranules. The spectrum levels off out to wavenumbers of about 400, and then rises again to a peak at a wavenumber of about 3500 (wavelength of about 1200 km), which is typical of granules. The velocity spectrum is dominated by the poloidal flow component (horizontal flows with divergence but no curl) at wavenumbers above 30. The toroidal flow component (hori...

  6. On algebraic structure of matter spectrum

    CERN Document Server

    Varlamov, V V

    2016-01-01

    An algebraic structure of matter spectrum is studied. It is shown that a base mathematical construction, lying in the ground of matter spectrum (introduced by Heisenberg) , is a two-level Hilbert space. Two-level structure of the Hilbert space is defined by the following pair: 1) a separable Hilbert space with operator algebras and fundamental symmetries; 2) a nonseparable (physical) Hilbert space with dynamical and gauge symmetries, that is, a space of states (energy levels) of the matter spectrum. The each state of matter spectrum is defined by a cyclic representation within Gel'fand-Naimark-Segal construction. A decomposition of the physical Hilbert space onto coherent subspaces is given. This decomposition allows one to describe the all observed spectrum of states on an equal footing, including lepton, meson and baryon sectors of the matter spectrum. Following to Heisenberg, we assume that there exist no fundamental particles, there exist fundamental symmetries. It is shown also that all the symmetries of...

  7. 一种动态带宽资源预留分配链路接入控制算法%A link access control algorithm based on dynamic bandwidth resource reservation allocation

    Institute of Scientific and Technical Information of China (English)

    郭小雪; 秦勇

    2012-01-01

    传统的基于带宽请求的固定资源预留链路接入控制算法(BRLAC)不能适应网络状态和业务需求的变化,针对该类算法接入成功率和系统带宽利用率不高的问题,基于概率分析了系统预留带宽的大小,并提出一种动态带宽资源预留分配链路接入控制算法(DBRRA),该算法通过判断业务流优先级允许动态地从其他业务流调整预留带宽。仿真实验证明,DBRRA算法有较高的接入成功率、系统带宽利用率和较好的时延特性。%The traditional static resource reservation link access control algorithm based on bandwidth request can not adapt to the network state and business requirements, aiming at problems of low access success rate and low utilization ratio of bandwidth resource, the paper analyses the probability of bandwidth reservation, and proposes a link access control algorithm based on dynamic bandwidth resource reservation allocation. The algorithm allows adjusting bandwidth from other low level business traffic dynamically by judging the priority of business traffic. The experimental results demonstrate that the algorithm can improve the link access success proportion, system bandwidth utilization and have better delay character.

  8. 在动态认知逻辑中融合观察与内省%Merging Observation and Access in Dynamic Epistemic Logic

    Institute of Scientific and Technical Information of China (English)

    约翰·范本特姆

    2008-01-01

    Logical systems have long been used to describe mathematical proof, structured computation, and linguistic meanings. In recent years, they are also coming to be used increas-ingly to study rational agency in its many aspects, from picking up single pieces of information to multi-agent actions of communication and goal-driven interaction generally. In particular, information flow through events of observation and communication has been studied using so-called dynamic epistemic logics of knowledge update, belief revision, and preference change. These logics use the 'semantic sense' of information as ranges of possible options which get updated as new information comes in.But equally importantly, rational agents also base their actions on information from other sources, such as inference and introspection. The latter is the area of more syntax-oriented senses of logical information as something which can be 'elucidated' by agents. Perhaps sur-prisingly, there is much less of a consensus on what this information is, and what its key mech-anisms consist in, though there are many competing proposals in the logical literature. Thus, logic is really a field with many different senses of 'information'.In this paper, we try to get clear on these issues by presenting one unified model of in-formation, based on semantic ranges of possible worlds, but endowed with syntactic 'access' to these worlds. This allows us to integrate external steps of 'updating information' and in-ternal steps of 'elucidating information' into one system of dynamic logic. In particular, we propose two kinds of basic informational action: pure observation-based update ('bare seeing') versus acts of 'conscious realization' which turn implicit knowledge into explicit knowledge. We show how this is a natural fit, which also provides many new research questions - many of them having to do with fitting further traditions into this picture of information-driven rational agency: including belief revision

  9. ROMANIA'S EU ACCESSION. GAINS AND LOSSES (I

    Directory of Open Access Journals (Sweden)

    Caba Stefan

    2012-07-01

    Full Text Available EU accession has brought, as expected, many changes in economic, social and cultural domains. An important chapter is the trade dynamics and how this dynamic has been modified over time by changes in the legal status of Romania's relations with certain trading partners. In this paper we present data on trade with countries with which Romania has concluded trade agreements before accession. Data presentation and analysis continues in "Romania's EU accession. Gains and losses (II".

  10. Code division multiple access (CDMA)

    CERN Document Server

    Buehrer, R Michael

    2006-01-01

    This book covers the basic aspects of Code Division Multiple Access or CDMA. It begins with an introduction to the basic ideas behind fixed and random access systems in order to demonstrate the difference between CDMA and the more widely understood TDMA, FDMA or CSMA. Secondly, a review of basic spread spectrum techniques are presented which are used in CDMA systems including direct sequence, frequency-hopping and time-hopping approaches. The basic concept of CDMA is presented, followed by the four basic principles of CDMA systems that impact their performance: interference averaging, universa

  11. Dissecting psychiatric spectrum disorders by generative embedding.

    Science.gov (United States)

    Brodersen, Kay H; Deserno, Lorenz; Schlagenhauf, Florian; Lin, Zhihao; Penny, Will D; Buhmann, Joachim M; Stephan, Klaas E

    2014-01-01

    This proof-of-concept study examines the feasibility of defining subgroups in psychiatric spectrum disorders by generative embedding, using dynamical system models which infer neuronal circuit mechanisms from neuroimaging data. To this end, we re-analysed an fMRI dataset of 41 patients diagnosed with schizophrenia and 42 healthy controls performing a numerical n-back working-memory task. In our generative-embedding approach, we used parameter estimates from a dynamic causal model (DCM) of a visual-parietal-prefrontal network to define a model-based feature space for the subsequent application of supervised and unsupervised learning techniques. First, using a linear support vector machine for classification, we were able to predict individual diagnostic labels significantly more accurately (78%) from DCM-based effective connectivity estimates than from functional connectivity between (62%) or local activity within the same regions (55%). Second, an unsupervised approach based on variational Bayesian Gaussian mixture modelling provided evidence for two clusters which mapped onto patients and controls with nearly the same accuracy (71%) as the supervised approach. Finally, when restricting the analysis only to the patients, Gaussian mixture modelling suggested the existence of three patient subgroups, each of which was characterised by a different architecture of the visual-parietal-prefrontal working-memory network. Critically, even though this analysis did not have access to information about the patients' clinical symptoms, the three neurophysiologically defined subgroups mapped onto three clinically distinct subgroups, distinguished by significant differences in negative symptom severity, as assessed on the Positive and Negative Syndrome Scale (PANSS). In summary, this study provides a concrete example of how psychiatric spectrum diseases may be split into subgroups that are defined in terms of neurophysiological mechanisms specified by a generative model of

  12. Dissecting psychiatric spectrum disorders by generative embedding

    Directory of Open Access Journals (Sweden)

    Kay H. Brodersen

    2014-01-01

    Full Text Available This proof-of-concept study examines the feasibility of defining subgroups in psychiatric spectrum disorders by generative embedding, using dynamical system models which infer neuronal circuit mechanisms from neuroimaging data. To this end, we re-analysed an fMRI dataset of 41 patients diagnosed with schizophrenia and 42 healthy controls performing a numerical n-back working-memory task. In our generative-embedding approach, we used parameter estimates from a dynamic causal model (DCM of a visual–parietal–prefrontal network to define a model-based feature space for the subsequent application of supervised and unsupervised learning techniques. First, using a linear support vector machine for classification, we were able to predict individual diagnostic labels significantly more accurately (78% from DCM-based effective connectivity estimates than from functional connectivity between (62% or local activity within the same regions (55%. Second, an unsupervised approach based on variational Bayesian Gaussian mixture modelling provided evidence for two clusters which mapped onto patients and controls with nearly the same accuracy (71% as the supervised approach. Finally, when restricting the analysis only to the patients, Gaussian mixture modelling suggested the existence of three patient subgroups, each of which was characterised by a different architecture of the visual–parietal–prefrontal working-memory network. Critically, even though this analysis did not have access to information about the patients' clinical symptoms, the three neurophysiologically defined subgroups mapped onto three clinically distinct subgroups, distinguished by significant differences in negative symptom severity, as assessed on the Positive and Negative Syndrome Scale (PANSS. In summary, this study provides a concrete example of how psychiatric spectrum diseases may be split into subgroups that are defined in terms of neurophysiological mechanisms specified by a

  13. Investment and Pricing with Spectrum Uncertainty: A Cognitive Operator's Perspective

    OpenAIRE

    Duan, Lingjie; Huang, Jianwei; Shou, Biying

    2009-01-01

    This paper studies the optimal investment and pricing decisions of a cognitive mobile virtual network operator (C-MVNO) under spectrum supply uncertainty. Compared with a traditional MVNO who often leases spectrum via long-term contracts, a C-MVNO can acquire spectrum dynamically in short-term by both sensing the empty "spectrum holes" of licensed bands and dynamically leasing from the spectrum owner. As a result, a C-MVNO can make flexible investment and pricing decisions to match the curren...

  14. A novel spectrum sharing scheme for cognitive radios

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel approach, which combines spectrum adaptation and orthogonal frequency division multiplexing (OFDM), is proposed to share the licensed spectrum dynamically for cognitive radio systems. Given spectrum sensing and channel estimation information by the receiver, an improved model due to signal power thresholds is adopted to achieve spectrum adaptation for unlicensed users. In order to efficiently allocate the unlicensed signal power, a dynamic power allocation algorithm is also proposed. Simulation results indicate that the propositional scheme solves the partial interference problem of interference temperature model (ITM) and improves the spectrum utilization.

  15. 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.

  16. Removing non-stationary noise in spectrum sensing using matrix factorization

    Science.gov (United States)

    van Bloem, Jan-Willem; Schiphorst, Roel; Slump, Cornelis H.

    2013-12-01

    Spectrum sensing is key to many applications like dynamic spectrum access (DSA) systems or telecom regulators who need to measure utilization of frequency bands. The International Telecommunication Union (ITU) recommends a 10 dB threshold above the noise to decide whether a channel is occupied or not. However, radio frequency (RF) receiver front-ends are non-ideal. This means that the obtained data is distorted with noise and imperfections from the analog front-end. As part of the front-end the automatic gain control (AGC) circuitry mainly affects the sensing performance as strong adjacent signals lift the noise level. To enhance the performance of spectrum sensing significantly we focus in this article on techniques to remove the noise caused by the AGC from the sensing data. In order to do this we have applied matrix factorization techniques, i.e., SVD (singular value decomposition) and NMF (non-negative matrix factorization), which enables signal space analysis. In addition, we use live measurement results to verify the performance and to remove the effects of the AGC from the sensing data using above mentioned techniques, i.e., applied on block-wise available spectrum data. In this article it is shown that the occupancy in the industrial, scientific and medical (ISM) band, obtained by using energy detection (ITU recommended threshold), can be an overestimation of spectrum usage by 60%.

  17. Intervening in global markets to improve access to HIV/AIDS treatment: an analysis of international policies and the dynamics of global antiretroviral medicines markets

    National Research Council Canada - National Science Library

    Waning, Brenda; Kyle, Margaret; Diedrichsen, Ellen; Soucy, Lyne; Hochstadt, Jenny; Bärnighausen, Till; Moon, Suerie

    2010-01-01

    ...) medicines, limited financing, and few fixed-dose combination (FDC) products. Global initiatives aim to promote efficient global ARV markets, yet little is known about market dynamics and the impact of global policy interventions...

  18. Extended-spectrum beta-lactamase-producing Klebsiella spp. in a neonatal intensive care unit: risk factors for the infection and the dynamics of the molecular epidemiology.

    Science.gov (United States)

    Kristóf, K; Szabó, D; Marsh, J W; Cser, V; Janik, L; Rozgonyi, F; Nobilis, A; Nagy, K; Paterson, D L

    2007-08-01

    The extended-spectrum beta-lactamase (ESBL)-producing Klebsiella spp. cause worldwide problems in intensive care units. The aim of this study was to investigate the molecular epidemiology of ESBL-producing Klebsiella pneumoniae and K. oxytoca strains in a neonatal intensive care unit (NICU) in Budapest, Hungary and to determine the risk factors of the infections and the epidemiological features. Infections with Klebsiella spp. were analyzed retrospectively by reviewing the medical records between January 2001 and December 2005. Antibiotic susceptibility tests, isoelectric focusing, pulsed field gel electrophoresis, plasmid analysis, PCR for bla(TEM) and bla(SHV) and DNA sequencing analysis were performed on ESBL-producing Klebsiella isolates. A total of 45 babies were found to be infected with non-ESBL-producing Klebsiella spp. and 39 with ESBL-producing Klebsiella spp. Of the parameters analyzed, including sex, gestational age, twin pregnancy, birth weight, presence of central vascular catheter, mechanical ventilator use, parenteral nutrition, polymicrobial infection, caesarean section, transfusion and mortality, we found no statistically significant difference between the ESBL and the non-ESBL groups, or between the K. pneumoniae and K. oxytoca species. Further characterization of the ESBL-producing K. pneumoniae and K. oxytoca strains isolated between February 2001 and January 2003 revealed three distinct PFGE patterns of SHV-5-producing K. pneumoniae (A, B, E) and two distinct patterns of SHV-12-producing K. oxytoca (C,D) isolates; these had different plasmid profiles. From July to November 2005, a new SHV-5 producing K. oxytoca (F) was isolated. The molecular epidemiology of ESBL-producing organisms in a NICU over time shows substantial shifts in predominant strains. The ESBL production of the infected organisms has an impact on the survival of newborn babies with infections caused by Klebsiella spp.

  19. Environment Implications of China's WTO Accession

    Institute of Scientific and Technical Information of China (English)

    Li Shantong; He Jianwu

    2006-01-01

    China's WTO accession will have important environmental implications. This article aims at providing environmental analysis of the impact of China's accession to the WTO, based on its final offer for WTO accession and a 53-sector, recursive dynamic computable general equilibrium (CGE) model of China. We try to provide some empirical evidences for policy makers to evaluate the effects of China's WTO accession from environmental prospective.

  20. Market-driven spectrum sharing in cognitive radio

    CERN Document Server

    Yi, Changyan

    2016-01-01

    This brief focuses on the current research on mechanism design for dynamic spectrum sharing in cognitive radio (CR) networks. Along with a review of CR architectures and characteristics, this brief presents the motivations, significances and unique challenges of implementing algorithmic mechanism design for encouraging both primary spectrum owners and secondary spectrum users to participate in dynamic spectrum sharing. The brief then focuses on recent advances in mechanism design in CR networks. With an emphasis on dealing with the uncertain spectrum availabilities, mechanisms based on spectrum recall, two-stage spectrum sharing and online spectrum allocation are introduced with the support of theoretic analyses and numerical illustrations. The brief concludes with a discussion of potential research directions and interests, which will motivate further studies on mechanism design for wireless communications. This brief is concise and approachable for researchers, professionals and advanced-level students in w...

  1. A new access scheme in OFDMA systems

    Institute of Scientific and Technical Information of China (English)

    GU Xue-lin; YAN Wei; TIAN Hui; ZHANG Ping

    2006-01-01

    This article presents a dynamic random access scheme for orthogonal frequency division multiple access (OFDMA) systems. The key features of the proposed scheme are:it is a combination of both the distributed and the centralized schemes, it can accommodate several delay sensitivity classes,and it can adjust the number of random access channels in a media access control (MAC) frame and the access probability according to the outcome of Mobile Terminals access attempts in previous MAC frames. For floating populated packet-based networks, the proposed scheme possibly leads to high average user satisfaction.

  2. Open and regionalised spectrum repositories for emerging countries

    CSIR Research Space (South Africa)

    Arcia-Moret, A

    2016-08-01

    Full Text Available the motivations and challenges for collecting spectrum measurements in developing regions and discuss a scalable system for communities to gather and provide access to White Spaces information through open and regionalised repositories. We further discuss two...

  3. A coupled stable isotope-size spectrum approach to understanding pelagic food-web dynamics: A case study from the southwest sub-tropical Pacific

    Science.gov (United States)

    Hunt, B. P. V.; Allain, V.; Menkes, C.; Lorrain, A.; Graham, B.; Rodier, M.; Pagano, M.; Carlotti, F.

    2015-03-01

    This study investigated the food web structure of the oligotrophic picophytoplankton-dominated pelagic ecosystem in the vicinity of New Caledonia, within the Archipelagic Deep Basin (ARCH) province of the southwest sub-tropical Pacific. Nitrogen stable isotope (δ15N) data were collected for mesozooplankton (0.2-2 mm), macrozooplankton (2-20 mm), micronekton (20-200 mm) and nekton (>200 mm) during 2002-2004 and 2011. Using a coupled δ15N size-spectrum approach, we estimated (1) organism trophic level (TL); (2) food chain length (FCL); (3) predator prey mass ratio (PPMR); and (4) transfer efficiency (TE). The role of phytoplankton size structure in determining these parameters was investigated. Applying a trophic enrichment factor (TEF) of 3.4, maximum TL was calculated at ~5. The number of TLs spanned by each length class was 1.97 for mesozooplankton, 2.07 for macrozooplankton, 2.75 for micronekton, and 2.21 for nekton. Estimated PPMR was 10,099:1 for mesozooplankton, 3683:1 for macrozooplankton/micronekton, and 2.44×105:1 for nekton, corresponding to TEs of 6.3%, 8.5% and 2.4%, respectively. PPMR and TE were strongly influenced by the TEF used, and TEF 3.4 likely over and underestimated PPMR and TE, respectively, for mesozooplankton and macrozooplankton/micronekton. Comparatively low PPMR for mesozooplankton and macrozooplankton/micronekton indicated longer food chains and higher connectivity within these groups than for the nekton. Conversely, the high PPMR yet high trophic niche width for the nekton indicated that they prey primarily on macrozooplankton/micronekton, with a relatively high degree of dietary specialisation. Our results are discussed in the context of other marine food webs. The ARCH food chain was found to be 1-1.5 trophic levels longer than the eutrophic micro-/nanophytoplankton-dominated Californian upwelling system, providing empirical support for the role of phytoplankton size in determining FCL. Group specific PPMR estimates demonstrated

  4. Analyses of dynamic characteristics and seismic response spectrum of pedestrian steel truss bridge%人行钢桁架桥动力特性及反应谱分析

    Institute of Scientific and Technical Information of China (English)

    何钰龙; 李超; 申杨凡; 孟庆超

    2015-01-01

    In order to study the characteristics of pedestrian steel truss bridge vibration and dynamic response under seismic action ,a finite element model of the bridge is built by ANSYS to conduct modal analysis and response spectrum analysis ,and the peak value responds of displacement at key sections are obtained .The results indicate that pedestrian steel truss bridge is more susceptible to vibration than railway truss bridge ,and the torsion deformation appears earlier ;pedestrian steel truss bridge is prone to the horizontal and vertical displacement ,and the mid‐span displacement response is larger with the top chord of displacement response than the lower chord large in seismic response spectrum .The conclusions can provide the reference basis for the seismic design of pedestrian steel truss bridge .%为研究人行钢桁架桥动力特性及在地震作用下的动力响应,运用ANSYS对某人行钢桁架桥进行模态分析,用反应谱分析法对其进行三向激励地震响应分析,得到关键截面及桁架杆件的动力响应。分析结果表明:人行钢桁架桥较铁路钢桁架桥更易发生振动,且扭转变形出现较早;在地震反应谱作用下,人行钢桁架桥较易出现横向及竖向位移,且跨中位移响应较大,上弦杆位移响应较下弦杆大。

  5. Progress towards the child mortality millennium development goal in urban sub-Saharan Africa: the dynamics of population growth, immunization, and access to clean water

    Directory of Open Access Journals (Sweden)

    Madise Nyovani

    2007-08-01

    Full Text Available Abstract Background Improvements in child survival have been very poor in sub-Saharan Africa (SSA. Since the 1990s, declines in child mortality have reversed in many countries in the region, while in others, they have either slowed or stalled, making it improbable that the target of reducing child mortality by two thirds by 2015 will be reached. This paper highlights the implications of urban population growth and access to health and social services on progress in achieving MDG 4. Specifically, it examines trends in childhood mortality in SSA in relation to urban population growth, vaccination coverage and access to safe drinking water. Methods Correlation methods are used to analyze national-level data from the Demographic and Health Surveys and from the United Nations. The analysis is complemented by case studies on intra-urban health differences in Kenya and Zambia. Results Only five of the 22 countries included in the study have recorded declines in urban child mortality that are in line with the MDG target of about 4% per year; five others have recorded an increase; and the 12 remaining countries witnessed only minimal decline. More rapid rate of urban population growth is associated with negative trend in access to safe drinking water and in vaccination coverage, and ultimately to increasing or timid declines in child mortality. There is evidence of intra-urban disparities in child health in some countries like Kenya and Zambia. Conclusion Failing to appropriately target the growing sub-group of the urban poor and improve their living conditions and health status – which is an MDG target itself – may result in lack of improvement on national indicators of health. Sustained expansion of potable water supplies and vaccination coverage among the disadvantaged urban dwellers should be given priority in the efforts to achieve the child mortality MDG in SSA.

  6. Implications of the dynamics of the new networked economy for e-business start-ups: the case of Philips’ Access Point

    NARCIS (Netherlands)

    Tovstiga, George; Fantner, Ernest J.

    2000-01-01

    Explores how the spread of connectivity and the introduction of new standards is driving the emergence of entirely new value constructs that deliver to multiple stakeholders. Examines the new economics of network growth and the associated “economics of increasing returns”. Looks at the dynamic traje

  7. Why Open Access?

    OpenAIRE

    2015-01-01

    As mentioned in the previous editorial (López-López, 2015), Suber’s (2015) book is a significant contribution that we can use to clarify the limits and the scope of Open Access (OA), and it is also helpful in explaining confusions and inaccuracies that are widespread in our communities, which are not quite ready to face the accelerated changes that are being generated by the new dynamics of scientific output and communication (Gallegos, Berra, Benito, & López-López, 2014). Suber (2015) st...

  8. Multi-channel Hybrid Access Femtocells: A Stochastic Geometric Analysis

    CERN Document Server

    Zhong, Yi

    2011-01-01

    For two-tier networks consisting of macrocells and femtocells, the channel access mechanism can be configured to be open access, closed access, or hybrid access. Hybrid access arises as a compromise between open and closed access mechanisms, in which a fraction of available spectrum resource is shared to nonsubscribers while the remaining reserved for subscribers. This paper focuses on a hybrid access mechanism for multi-channel femtocells which employ orthogonal spectrum access schemes. Considering a randomized channel assignment strategy, we analyze the performance in the downlink. Using stochastic geometry as technical tools, we derive the distributions of signal-to-interference-plus-noise ratios, and mean achievable rates, of both nonsubscribers and subscribers. The established expressions are amenable to numerical evaluation, and shed key insights into the performance tradeoff between subscribers and nonsubscribers. The analytical results are corroborated by numerical simulations.

  9. 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.……

  10. Dynamic, ecological, accessible and 3D Virtual Worlds-based Libraries using OpenSim and Sloodle along with mobile location and NFC for checking in

    Directory of Open Access Journals (Sweden)

    Ruben Gonzalez Crespo

    2012-12-01

    Full Text Available This paper proposes the implementation of a 3D virtual library, using open platforms such as OpenSimulator and Sloodle, applied to the integration of virtual learning environments. It also proposes their application to the creation of open libraries to share and disseminate the new dynamic nature of knowledge, in the understanding that 3D virtual worlds may contribute to the future of libraries as part of green initiatives to achieve an ecologic and sustainable planet.

  11. Precision Prediction of the Log Power Spectrum

    CERN Document Server

    Repp, Andrew

    2016-01-01

    At translinear scales, the log power spectrum captures significantly more cosmological information than the standard power spectrum. At high wavenumbers $k$, the cosmological information in the standard power spectrum $P(k)$ fails to increase in proportion to $k$ due to correlations between large- and small-scale modes. As a result, $P(k)$ suffers from an information plateau on these translinear scales, so that analysis with the standard power spectrum cannot access the information contained in these small-scale modes. The log power spectrum $P_A(k)$, on the other hand, captures the majority of this otherwise lost information. Until now there has been no means of predicting the amplitude of the log power spectrum apart from cataloging the results of simulations. We here present a cosmology-independent prescription for the log power spectrum, and we find this prescription to display accuracy comparable to that of Smith et al. (2003), over a range of redshifts and smoothing scales, and for wavenumbers up to $1....

  12. 有机小分子溶液的红外吸收光谱的分子动力学模拟%Molecular Dynamics Simulation of Infrared Absorption Spectrum of Small Organic Molecular Liquids

    Institute of Scientific and Technical Information of China (English)

    丁杨; 毛英臣; 许佩军; 宛素钰; 刘锐; 李贝贝

    2013-01-01

      在 AMOEBA 极化力场下对水、甲醇和乙醇溶液的红外吸收光谱进行了分子动力学模拟,与传统力场的计算结果相比,更好地符合了实验结果。这主要由于考虑了电多极矩效应和诱导偶极矩效应, AMOEBA力场对静电相互作用进行精确的描述,进而较好地模拟了化学键的弯曲振动和伸缩振动。%The aim of this paper is to study the infrared spectrum of water, methanol and ethanol liquids by molecular dynamics simulations. Compared with the results by the simulations based on the traditional force fields, the results from the simulations with the AMOEBA polarizable force field are more in line with the experiment results. The critical reason is that AMOEBA force field describes the electrostatic interaction much better than others force fields due to the electric multipole effects and the induced dipole effect considered in the field, and makes the bend vibration and the stretch vibration of molecular bonds more accurately determined in the simulation.

  13. Green energy : enabling technologies : international trends in utility wireless spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Moroney, W. [Utilities Telecom Council, Washington, DC (United States)

    2009-07-01

    The Utilities Telecom Council (UTC) is an international trade association that represents the interests of electric, gas and water utilities in the area of information and communications technology (ICT). This presentation provided background information on the UTC, with particular reference to its history; reporting relationships of the Board of Directors and the various divisions of the association; and radio spectrum. The UTC has been the leading advocate for critical infrastructure industries access to the spectrum since its creation in 1948. The radio spectrum was outlined in detail, including global efforts; Canadian, American, and European frequency allocations; the need for the spectrum; and the bottom-line. It was concluded that governments around the globe are moving to understand that utilities require access to interference-free radio spectrum if the benefits of intelligence in the grid are to be fully realized in a timely and cost-effective manner. 7 figs.

  14. Heavy hadron spectrum and interactions

    CERN Document Server

    Ebert, D

    1996-01-01

    Starting from the approximate symmetries of QCD, namely chiral symmetry for light quarks and spin and flavor symmetry for heavy quarks, we investigate the low-energy properties of heavy hadrons. For this purpose we construct a consistent picture of quark-antiquark and quark-diquark interactions as a low-energy approximation to the flavor dynamics in heavy mesons and heavy baryons, respectively. Using standard functional integration tools, we derive an effective Lagrangian in terms of heavy hadron fields and discuss several properties, like the mass spectrum, coupling and decay constants, Isgur-Wise form factors.

  15. Binary Sequences for Spread-Spectrum Multiple-Access Communication

    Science.gov (United States)

    1977-08-01

    represents an n-stage linear feedback shift register where 1 and for 0 < i < n, fi 1 if there is a feedback th "tap connected to the i stage of the...u:045,. v:075; k Efl and 1fl ;P 31. Wk 5 10 20 9 18 U V 0 2006 1942 2050 1846 1830 1742 1702 5 1854 2578 2470 1918 2190 2142 10 1898 2406 1830 1846

  16. Dynamic characteristics of undoped and p-doped Fabry-Perot InAs/InP quantum dash based ridge waveguide lasers for access/metro networks

    Energy Technology Data Exchange (ETDEWEB)

    Mollet, O., E-mail: oriane.mollet@lpn.cnrs.fr; Martinez, A.; Merghem, K.; Ramdane, A. [CNRS, Laboratory for Photonics and Nanostructures, Route de Nozay, 91460 Marcoussis (France); Joshi, S.; Provost, J.-G.; Lelarge, F. [III-V Lab, A Joint Laboratory of Alcatel Lucent Bell Laboratories, Thales Research and Technology and CEA-LETI, Route de Nozay, 91460 Marcoussis (France)

    2014-10-06

    In this paper, we report the characteristics of InAs/InP quantum dashes (QDash) based lasers emitting around 1.55 μm. An unprecedented high modal gain of ∼100 cm{sup −1} is obtained for an optimized active structure by stacking 12 QDash layers. Directly modulated lasers allowed achieving a modulation bandwidth of ∼10 GHz and a Henry factor around 5. Thanks to p-type doping, the Henry factor value is reduced down to 2.7 while the modulation bandwidth still amounts to ∼10 GHz. This shows that doping of the active region is important to improve the dynamic characteristics of QDash lasers.

  17. Static and Dynamic 4-Way Handshake Solutions to Avoid Denial of Service Attack in Wi-Fi Protected Access and IEEE 802.11i

    Directory of Open Access Journals (Sweden)

    De Rango Floriano

    2006-01-01

    Full Text Available This paper focuses on WPA and IEEE 802.11i protocols that represent two important solutions in the wireless environment. Scenarios where it is possible to produce a DoS attack and DoS flooding attacks are outlined. The last phase of the authentication process, represented by the 4-way handshake procedure, is shown to be unsafe from DoS attack. This can produce the undesired effect of memory exhaustion if a flooding DoS attack is conducted. In order to avoid DoS attack without increasing the complexity of wireless mobile devices too much and without changing through some further control fields of the frame structure of wireless security protocols, a solution is found and an extension of WPA and IEEE 802.11 is proposed. A protocol extension with three "static" variants and with a resource-aware dynamic approach is considered. The three enhancements to the standard protocols are achieved through some simple changes on the client side and they are robust against DoS and DoS flooding attack. Advantages introduced by the proposal are validated by simulation campaigns and simulation parameters such as attempted attacks, successful attacks, and CPU load, while the algorithm execution time is evaluated. Simulation results show how the three static solutions avoid memory exhaustion and present a good performance in terms of CPU load and execution time in comparison with the standard WPA and IEEE 802.11i protocols. However, if the mobile device presents different resource availability in terms of CPU and memory or if resource availability significantly changes in time, a dynamic approach that is able to switch among three different modalities could be more suitable.

  18. Processing keyword queries under access limitations

    OpenAIRE

    Calì, Andrea; Martinenghi, D.; Torlone, R.

    2015-01-01

    The Deep Web is constituted by data accessible through Web pages, but not readily indexable by search engines, as they are returned in dynamic pages. In this paper we propose a framework for accessing Deep Web sources, represented as relational tables with so-called access limitations, with keyword-based queries. We formalize the notion of optimal answer and propose methods for query processing. To the best of our knowledge, ours is the first systematic approach to keyword search in such cont...

  19. Nonlinear dynamics by mode superposition

    Energy Technology Data Exchange (ETDEWEB)

    Nickell, R.E.

    1976-01-01

    A mode superposition technique for approximately solving nonlinear initial-boundary-value problems of structural dynamics is discussed, and results for examples involving large deformation are compared to those obtained with implicit direct integration methods such as the Newmark generalized acceleration and Houbolt backward-difference operators. The initial natural frequencies and mode shapes are found by inverse power iteration with the trial vectors for successively higher modes being swept by Gram-Schmidt orthonormalization at each iteration. The subsequent modal spectrum for nonlinear states is based upon the tangent stiffness of the structure and is calculated by a subspace iteration procedure that involves matrix multiplication only, using the most recently computed spectrum as an initial estimate. Then, a precise time integration algorithm that has no artificial damping or phase velocity error for linear problems is applied to the uncoupled modal equations of motion. Squared-frequency extrapolation is examined for nonlinear problems as a means by which these qualities of accuracy and precision can be maintained when the state of the system (and, thus, the modal spectrum) is changing rapidly. The results indicate that a number of important advantages accrue to nonlinear mode superposition: (a) there is no significant difference in total solution time between mode superposition and implicit direct integration analyses for problems having narrow matric half-bandwidth (in fact, as bandwidth increases, mode superposition becomes more economical), (b) solution accuracy is under better control since the analyst has ready access to modal participation factors and the ratios of time step size to modal period, and (c) physical understanding of nonlinear dynamic response is improved since the analyst is able to observe the changes in the modal spectrum as deformation proceeds.

  20. Autism Spectrum Disorder (ASD)

    Science.gov (United States)

    ... Español (Spanish) Recommend on Facebook Tweet Share Compartir Autism spectrum disorder (ASD) is a developmental disability that can cause ... factors that may put children at risk for autism spectrum disorder (ASD) and other developmental disabilities. More E-mail ...

  1. The CMBR spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Stebbins, A.

    1997-05-01

    Here we give an introduction to the observed spectrum of the Cosmic Microwave Background Radiation (CMBR) and discuss what can be learned about it. Particular attention will be given to how Compton scattering can distort the spectrum of the CMBR. An incomplete bibliography of relevant papers is also provided.

  2. 5G Spectrum Sharing

    OpenAIRE

    Nekovee, Maziar; Rudd, Richard

    2017-01-01

    In this paper an overview is given of the current status of 5G industry standards, spectrum allocation and use cases, followed by initial investigations of new opportunities for spectrum sharing in 5G using cognitive radio techniques, considering both licensed and unlicensed scenarios. A particular attention is given to sharing millimeter-wave frequencies, which are of prominent importance for 5G.

  3. Fetal Alcohol Spectrum Disorder

    Science.gov (United States)

    Caley, Linda M.; Kramer, Charlotte; Robinson, Luther K.

    2005-01-01

    Fetal alcohol spectrum disorder (FASD) is a serious and widespread problem in this country. Positioned within the community with links to children, families, and healthcare systems, school nurses are a critical element in the prevention and treatment of those affected by fetal alcohol spectrum disorder. Although most school nurses are familiar…

  4. Power spectrum analysis for defect screening in integrated circuit devices

    Science.gov (United States)

    Tangyunyong, Paiboon; Cole Jr., Edward I.; Stein, David J.

    2011-12-01

    A device sample is screened for defects using its power spectrum in response to a dynamic stimulus. The device sample receives a time-varying electrical signal. The power spectrum of the device sample is measured at one of the pins of the device sample. A defect in the device sample can be identified based on results of comparing the power spectrum with one or more power spectra of the device that have a known defect status.

  5. Wave Reflection Coefficient Spectrum

    Institute of Scientific and Technical Information of China (English)

    俞聿修; 邵利民; 柳淑学

    2003-01-01

    The wave reflection coefficient frequency spectrum and directional spectrum for concrete face slope breakwaters and rubble mound breakwaters are investigated through physical model tests in the present study. The reflection coefficients of oblique irregular waves are analyzed by the Modified Two-Point Method (MTPM) proposed by the authors. The results show that the wave reflection coefficient decreases with increasing wave frequency and incident angle or decreasing structure slope. The reflection coefficient frequency spectrum and its variation with Iribarren number are given in this paper. The paper also suggests an empirical 3-dimensional reflection coefficient spectrum, i.e. reflection coefficient directional spectrum, which can be used to illustrate quantitatively the variation of reflection coefficient with the incident angle and the Iribarren number for oblique irregular waves.

  6. 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....

  7. Inter-operator spectrum sharing scheme for reconfigurable system

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Bargaining based mechanism for sharing spectrum between radio access networks (RANs) belonging to multioperators is studied, to improve spectrum utilization efficiency and maximize network revenue.By introducing an intelligent agent, each RAN has the ability, which includes trading information exchanging, final decision making, and so on, to trade the spectrum with other RANs.The proposed inter-operator spectrum sharing mechanism is modeled as an infinite-horizon bargaining game with incomplete information, and the resulting bargaining game has unique sequential equilibrium.Consequently, the implementation is refined based on the analysis.Simulation results show that the proposed mechanism outperforms the conventional fixed spectrum management (FSM) method in network revenue, spectrum efficiency, and call blocking rate.

  8. VT Limited Access Highways

    Data.gov (United States)

    Vermont Center for Geographic Information — A limited-access road, known by various terms worldwide, including limited-access highway, dual carriageway, expressway, and partial controlled access highway, is a...

  9. Dynamic triggering

    Science.gov (United States)

    Hill, David P.; Prejean, Stephanie; Schubert, Gerald

    2015-01-01

    Dynamic stresses propagating as seismic waves from large earthquakes trigger a spectrum of responses at global distances. In addition to locally triggered earthquakes in a variety of tectonic environments, dynamic stresses trigger tectonic (nonvolcanic) tremor in the brittle–plastic transition zone along major plate-boundary faults, activity changes in hydrothermal and volcanic systems, and, in hydrologic domains, changes in spring discharge, water well levels, soil liquefaction, and the eruption of mud volcanoes. Surface waves with periods of 15–200 s are the most effective triggering agents; body-wave trigger is less frequent. Triggering dynamic stresses can be < 1 kPa.

  10. Jumping Dynamics

    DEFF Research Database (Denmark)

    Sannino, Francesco

    2013-01-01

    We propose an alternative paradigm to the conjectured Miransky scaling potentially underlying the physics describing the transition from the conformally broken to the conformally restored phase when tuning certain parameters such as the number of flavors in gauge theories. According to the new...... paradigm the physical scale and henceforth also the massive spectrum of the theory jump at the lower boundary of the conformal window. In particular we propose that a theory can suddenly jump from a Quantum Chromodynamics type spectrum, at the lower boundary of the conformal window, to a conformal one...... without particle interpretation. The jumping scenario, therefore, does not support a near-conformal dynamics of walking type. We will also discuss the impact of jumping dynamics on the construction of models of dynamical electroweak symmetry breaking....

  11. PROPOSAL OF "GROUND RESPONSE SPECTRUM" AND PRESENTATION OF THEIR EXAMPLES

    Science.gov (United States)

    Shiba, Yukio

    "Ground response spectrum" is proposed in this paper. "Ground response spectrum" is the graph which is so drawn as to read the maximum values of dynamic responses of subsurface ground to a seismic accelerograph, such as particle acceleration, velocity, displacement on the surface and shear strain caused in the ground. The calculation method of the spectrum is the same as the ordinary response spectrum except the use of simple one-dimensional continuum of linear viscoelastic medium; instead a single-degree-of-freedom oscillation system is used in the calculation of ordinary response spectrum. A few examples of the "ground response spectrum" are presented and special feature and usefulness of the spectrum is discussed in this paper.

  12. 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.

  13. Excitation Spectrum of Three Dressed Bose-Einstein Condensates

    Institute of Scientific and Technical Information of China (English)

    OU-YANG Zhong-Wen; KUANG Le-Man

    2000-01-01

    We study quantum dynamics of three dressed Bose-Einstein condensates in a high-Q cavity. The quasiparticle excitation spectrum of this system is found numerically. The stability of the quasiparticle excitation is analyzed. It is shown that there exist instabilities in the excitation spectrum.

  14. VHF spectrum monitoring using Meraka cognitive radio platform

    CSIR Research Space (South Africa)

    Aderonmu, AI

    2012-11-01

    Full Text Available to the enhancement of new techniques for better utilization of the RF spectrums. The questions asked are how much RF spectrum is available and can be used opportunistically and dynamically without interfering with licensed or primary users (PUs)? More so, how...

  15. Fishing Access Areas

    Data.gov (United States)

    Vermont Center for Geographic Information — The Vermont Fish & Wildlife Department maintains developed fishing access areas. These sites provide public access to waters in Vermont for shore fishing...

  16. 动态约束下的风电场最大可接入容量研究%Research on maximum access capacity of wind farm based on dynamic constraints

    Institute of Scientific and Technical Information of China (English)

    张俊; 晁勤; 段晓田; 袁铁江

    2011-01-01

    基于DIgSILENT/Power Factory仿真平台建立了新疆某地区含风电场的电力系统仿真模型,以电压和频率两个电气量作为动态约束条件,通过对风电场的穿透功率极限的计算和仿真,确定了该地区电网的风电场最大可接入容量.研究结果表明:采用频率约束法计算和时域仿真分析相结合确定的风电场最大可接入容量,能保证风电系统的稳定运行;并且优化影响风电系统稳定运行的因素和不同约束条件,对确定系统的风电场最大可接入容量和风电场的设计、运行和规划都有重要意义.%In this paper, a simulation model of power system with wind farm in some area of Xinjiang is established based on the DIgSILENT/Power Factory simulation platform. The wind power penetration limit is calculated and simulated with voltage and frequency being considered as dynamic constraints, and then the maximum access capacity of wind power plant of Xinjiang is determined. Research results show that the maximum access capacity of wind farm that determined by the combination of the frequency restriction and the time simulation can ensure the stability of wind power system. Besides, the optimization of some factors and other security constraints play a significant role in determining the maximum access capacity of wind farm and its designing,operating and planning.This work is supported by National Natural Science Foundation of China (No. 50667002).

  17. A service-oriented data access control model

    Science.gov (United States)

    Meng, Wei; Li, Fengmin; Pan, Juchen; Song, Song; Bian, Jiali

    2017-01-01

    The development of mobile computing, cloud computing and distributed computing meets the growing individual service needs. Facing with complex application system, it's an urgent problem to ensure real-time, dynamic, and fine-grained data access control. By analyzing common data access control models, on the basis of mandatory access control model, the paper proposes a service-oriented access control model. By regarding system services as subject and data of databases as object, the model defines access levels and access identification of subject and object, and ensures system services securely to access databases.

  18. Probability-consistent spectrum and code spectrum

    Institute of Scientific and Technical Information of China (English)

    沈建文; 石树中

    2004-01-01

    In the seismic safety evaluation (SSE) for key projects, the probability-consistent spectrum (PCS), usually obtained from probabilistic seismic hazard analysis (PSHA), is not consistent with the design response spectrum given by Code for Seismic Design of Buildings (GB50011-2001). Sometimes, there may be a remarkable difference between them. If the PCS is lower than the corresponding code design response spectrum (CDS), the seismic fortification criterion for the key projects would be lower than that for the general industry and civil buildings. In the paper, the relation between PCS and CDS is discussed by using the ideal simple potential seismic source. The results show that in the most areas influenced mainly by the potential sources of the epicentral earthquakes and the regional earthquakes, PCS is generally lower than CDS in the long periods. We point out that the long-period response spectra of the code should be further studied and combined with the probability method of seismic zoning as much as possible. Because of the uncertainties in SSE, it should be prudent to use the long-period response spectra given by SSE for key projects when they are lower than CDS.

  19. Uplink Access Schemes for LTE-Advanced

    Science.gov (United States)

    Liu, Le; Inoue, Takamichi; Koyanagi, Kenji; Kakura, Yoshikazu

    The 3GPP LTE-Advanced has been attracting much attention recently, where the channel bandwidth would be beyond the maximum bandwidth of LTE, 20MHz. In LTE, single carrier-frequency division multiple access (SC-FDMA) was accepted as the uplink access scheme due to its advantage of very low cubic metric (CM). For LTE-A wideband transmission, multicarrier access would be more effective than single carrier access to make use of multi-user diversity and can maintain the physical channel structure of LTE, where the control information is transmitted on the edges of each 20MHz. In this paper, we discuss the access schemes in bandwidth under 20MHz as well as over 20MHz. In the case of bandwidth under 20MHz, we propose the access schemes allowing discontinuous resource allocation to enhance average throughput while maintaining cell-edge user throughput, that is, DFT-spread-OFDM with spectrum division control (SDC) and adaptive selection of SC-FDMA and OFDM (SC+OFDM). The number of discontinuous spectrums is denoted as spectrum division (SD). For DFT-S-OFDM, we define a parameter max SD as the upper limit of SD. We evaluate our proposed schemes in bandwidth under 20MHz and find that SC+OFDM as well as SDC with common max SD or UE-specific max SD can improve average throughput while their cell-edge user throughput can approach that of SC-FDMA. In the case of bandwidth over 20MHz, we consider key factors to decide a feasible access scheme for aggregating several 20MHz-wide bands.

  20. JISC Open Access Briefing Paper

    OpenAIRE

    Swan, Alma

    2005-01-01

    What Open Access is. What Open Access is not. How is Open Access provided? Open Access archives or repositories. Open Access journals. Why should authors provide Open Access to their work? Further information and resources

  1. JISC Open Access Briefing Paper

    OpenAIRE

    Swan, Alma

    2005-01-01

    What Open Access is. What Open Access is not. How is Open Access provided? Open Access archives or repositories. Open Access journals. Why should authors provide Open Access to their work? Further information and resources

  2. Quantum game application to spectrum scarcity problems

    Science.gov (United States)

    Zabaleta, O. G.; Barrangú, J. P.; Arizmendi, C. M.

    2017-01-01

    Recent spectrum-sharing research has produced a strategy to address spectrum scarcity problems. This novel idea, named cognitive radio, considers that secondary users can opportunistically exploit spectrum holes left temporarily unused by primary users. This presents a competitive scenario among cognitive users, making it suitable for game theory treatment. In this work, we show that the spectrum-sharing benefits of cognitive radio can be increased by designing a medium access control based on quantum game theory. In this context, we propose a model to manage spectrum fairly and effectively, based on a multiple-users multiple-choice quantum minority game. By taking advantage of quantum entanglement and quantum interference, it is possible to reduce the probability of collision problems commonly associated with classic algorithms. Collision avoidance is an essential property for classic and quantum communications systems. In our model, two different scenarios are considered, to meet the requirements of different user strategies. The first considers sensor networks where the rational use of energy is a cornerstone; the second focuses on installations where the quality of service of the entire network is a priority.

  3. The Spectrum of Wind Power Fluctuations

    Science.gov (United States)

    Bandi, Mahesh

    2016-11-01

    Wind is a variable energy source whose fluctuations threaten electrical grid stability and complicate dynamical load balancing. The power generated by a wind turbine fluctuates due to the variable wind speed that blows past the turbine. Indeed, the spectrum of wind power fluctuations is widely believed to reflect the Kolmogorov spectrum; both vary with frequency f as f - 5 / 3. This variability decreases when aggregate power fluctuations from geographically distributed wind farms are averaged at the grid via a mechanism known as geographic smoothing. Neither the f - 5 / 3 wind power fluctuation spectrum nor the mechanism of geographic smoothing are understood. In this work, we explain the wind power fluctuation spectrum from the turbine through grid scales. The f - 5 / 3 wind power fluctuation spectrum results from the largest length scales of atmospheric turbulence of order 200 km influencing the small scales where individual turbines operate. This long-range influence spatially couples geographically distributed wind farms and synchronizes farm outputs over a range of frequencies and decreases with increasing inter-farm distance. Consequently, aggregate grid-scale power fluctuations remain correlated, and are smoothed until they reach a limiting f - 7 / 3 spectrum. This work was funded by the Collective Interactions Unit, OIST Graduate University, Japan.

  4. The marine diversity spectrum

    DEFF Research Database (Denmark)

    Reuman, Daniel C.; Gislason, Henrik; Barnes, Carolyn

    2014-01-01

    of taxonomy (all the species in a region regardless of clade) are much less studied but are equally important and will illuminate a different set of ecological and evolutionary processes. We develop and test a mechanistic model of how diversity varies with body mass in marine ecosystems. The model predicts...... the form of the diversity spectrum', which quantifies the distribution of species' asymptotic body masses, is a species analogue of the classic size spectrum of individuals, and which we have found to be a new and widely applicable description of diversity patterns. The marine diversity spectrum...... is predicted to be approximately linear across an asymptotic mass range spanning seven orders of magnitude. Slope -0 center dot 5 is predicted for the global marine diversity spectrum for all combined pelagic zones of continental shelf seas, and slopes for large regions are predicted to lie between -0 center...

  5. Fast Spectrum Reactors

    CERN Document Server

    Todd, Donald; Tsvetkov, Pavel

    2012-01-01

    Fast Spectrum Reactors presents a detailed overview of world-wide technology contributing to the development of fast spectrum reactors. With a unique focus on the capabilities of fast spectrum reactors to address nuclear waste transmutation issues, in addition to the well-known capabilities of breeding new fuel, this volume describes how fast spectrum reactors contribute to the wide application of nuclear power systems to serve the global nuclear renaissance while minimizing nuclear proliferation concerns. Readers will find an introduction to the sustainable development of nuclear energy and the role of fast reactors, in addition to an economic analysis of nuclear reactors. A section devoted to neutronics offers the current trends in nuclear design, such as performance parameters and the optimization of advanced power systems. The latest findings on fuel management, partitioning and transmutation include the physics, efficiency and strategies of transmutation, homogeneous and heterogeneous recycling, in addit...

  6. Real-time Dynamic Spectrum Management in OFDM-based High-data Rate Narrowband Power Line Communications%高速窄带OFDM电力线通信实时动态频谱分配

    Institute of Scientific and Technical Information of China (English)

    张童飞; 郭静波

    2014-01-01

    A lot of challenges have to be solved in implementation of dynamic spectrum management (DSM) such as allocation strategy and the related real time algorithm, and yet there is no such work reported publicly. Architecture of an actual orthogonal frequency division multiplexing (OFDM)-based high data rate narrowband power line communication (HDR NB PLC) system was defined and designed, and a novel strategy of DSM and the related real time algorithm suitable for the system was proposed. Under a given dimension of modulation, the algorithm partitioned the subcarriers, sorted them in power order,chose the available group, and finally determined the best modulation scheme and optimally allocated the power according to the rate maximization criteria. Comparing to the typical Hughes-Hartogs algorithm, the proposed algorithm has lower computational complexity and less signaling overhead. Comparing with conventional constant power allocation, the algorithm has a better performance of bit error rate. Simulation and experimental results verified the effectiveness and advantages of the algorithm.%动态频谱分配应用于实际电力线通信系统面临分配策略、实时算法等诸多挑战,到目前为止还未见有公开报道。定义并设计了一个实际的基于正交频分复用(orthogonal frequency division multiplexing,OFDM)的高速窄带电力线通信系统构架,并提出一种适用于该系统的动态频谱分配策略和对应的实时实现算法。该算法在任一种调制方式下将子载波进行分组,并对各个子载波组的功率进行排序,选择可用的子载波组,根据速率最大化准则确定最优的调制方式并分配功率。该算法与 Hughes-Hartogs 算法相比,具有较低的运算复杂度和较少的信令开销,与传统的等功率分配方式相比,误码性能更好。仿真结果和实验结果证明了该算法的有效性和优越性。

  7. Spectrum and network measurements

    CERN Document Server

    Witte, Robert A

    2014-01-01

    This new edition of Spectrum and Network Measurements enables readers to understand the basic theory, relate it to measured results, and apply it when creating new designs. This comprehensive treatment of frequency domain measurements successfully consolidates all the pertinent theory into one text. It covers the theory and practice of spectrum and network measurements in electronic systems. It also provides thorough coverage of Fourier analysis, transmission lines, intermodulation distortion, signal-to-noise ratio and S-parameters.

  8. Maximizing the utility of radio spectrum: Broadband spectrum measurements and occupancy model for use by cognitive radio

    Science.gov (United States)

    Petrin, Allen J.

    Radio spectrum is a vital national asset; proper management of this finite resource is essential to the operation and development of telecommunications, radio-navigation, radio astronomy, and passive remote sensing services. To maximize the utility of the radio spectrum, knowledge of its current usage is beneficial. As a result, several spectrum studies have been conducted in urban Atlanta, suburban Atlanta, and rural North Carolina. These studies improve upon past spectrum studies by resolving spectrum usage by nearly all its possible parameters: frequency, time, polarization, azimuth, and location type. The continuous frequency range from 400MHz to 7.2 GHz was measured with a custom-designed system. More than 8 billion spectrum measurements were taken over several months of observation. A multi-parameter spectrum usage detection method was developed and analyzed with data from the spectrum studies. This method was designed to exploit all the characteristics of spectral information that was available from the spectrum studies. Analysis of the spectrum studies showed significant levels of underuse. The level of spectrum usage in time and azimuthal space was determined to be only 6.5 % for the urban Atlanta, 5.3 % for suburban Atlanta, and 0.8 % for the rural North Carolina spectrum studies. Most of the frequencies measured never experienced usage. Interference was detected in several protected radio astronomy and sensitive radio navigation bands. A cognitive radio network architecture to share spectrum with fixed microwave systems was developed. The architecture uses a broker-based sharing method to control spectrum access and investigate interference issues.

  9. CERN Access Cards and Access Authorisations

    CERN Multimedia

    2003-01-01

    From the 01/05/2003, all problems relating to access cards and refusal of access to any zone, building or experiment within CERN must be addressed to the Centrale de Surveillance des Accès (CSA building 120) on 78877 or send an e-mail to Access.Surveillance@cern.ch. The responsibles for CERN access control have put into place a procedure with the CSA, Service Enregistrement and the Technical Control Room, to make sure that all problems get resolved in a proper and timely manner.

  10. Cognitive Access to TVWS in India

    DEFF Research Database (Denmark)

    Patil, Kishor P.; Skouby, Knud Erik; Prasad, Ramjee

    2013-01-01

    performed spectrum measurements of TV band in Pune, India. Our result shows poor spectrum utilization in TV band, and good potential for Cognitive radio operation. Digital switchover in India will generate golden opportunity for empowering rural India. As majority of India’s population lives in rural part...... of India, we have proposed wireless broadband access to rural areas using TV White Spaces (TVWSs). This will help in bridging the digital divide by offering governance, banking, and health services online in the rural areas....

  11. Synchrotron radiation x-ray photoelectron spectroscopy study on the interface chemistry of high-k PrxAl2-xO3 (x=0-2) dielectrics on TiN for dynamic random access memory applications

    Science.gov (United States)

    Schroeder, T.; Lupina, G.; Sohal, R.; Lippert, G.; Wenger, Ch.; Seifarth, O.; Tallarida, M.; Schmeisser, D.

    2007-07-01

    Engineered dielectrics combined with compatible metal electrodes are important materials science approaches to scale three-dimensional trench dynamic random access memory (DRAM) cells. Highly insulating dielectrics with high dielectric constants were engineered in this study on TiN metal electrodes by partly substituting Al in the wide band gap insulator Al2O3 by Pr cations. High quality PrAlO3 metal-insulator-metal capacitors were processed with a dielectric constant of 19, three times higher than in the case of Al2O3 reference cells. As a parasitic low dielectric constant interface layer between PrAlO3 and TiN limits the total performance gain, a systematic nondestructive synchrotron x-ray photoelectron spectroscopy study on the interface chemistry of PrxAl2-xO3 (x =0-2) dielectrics on TiN layers was applied to unveil its chemical origin. The interface layer results from the decreasing chemical reactivity of PrxAl2-xO3 dielectrics with increasing Pr content x to reduce native Ti oxide compounds present on unprotected TiN films. Accordingly, PrAlO3 based DRAM capacitors require strict control of the surface chemistry of the TiN electrode, a parameter furthermore of importance to engineer the band offsets of PrxAl2-xO3/TiN heterojunctions.

  12. Accessibility and sensory experiences

    DEFF Research Database (Denmark)

    Ryhl, Camilla

    2010-01-01

    This article introduces a new design concept; sensory accessibility. While acknowledging the importance of sensory experiences in architectural quality, as well as the importance of accommodating user needs the concept combines three equally important factors; architecture, the senses and accessi......This article introduces a new design concept; sensory accessibility. While acknowledging the importance of sensory experiences in architectural quality, as well as the importance of accommodating user needs the concept combines three equally important factors; architecture, the senses...... and accessibility. Sensory accessibility accommodates aspects of a sensory disability and describes architectural design requirements needed to ensure access to architectural experiences. In the context of architecture accessibility has become a design concept of its own. It is generally described as ensuring...... physical access to the built environment by accommodating physical disabilities. While the existing concept of accessibility ensures the physical access of everyone to a given space, sensory accessibility ensures the choice of everyone to stay and be able to participate and experience....

  13. Optimizing Spectrum Trading in Cognitive Mesh Network Using Machine Learning

    Directory of Open Access Journals (Sweden)

    Ayoub Alsarhan

    2012-01-01

    Full Text Available In a cognitive wireless mesh network, licensed users (primary users, PUs may rent surplus spectrum to unlicensed users (secondary users, SUs for getting some revenue. For such spectrum sharing paradigm, maximizing the revenue is the key objective of the PUs while that of the SUs is to meet their requirements. These complex contradicting objectives are embedded in our reinforcement learning (RL model that is developed and implemented as shown in this paper. The objective function is defined as the net revenue gained by PUs from renting some of their spectrum. RL is used to extract the optimal control policy that maximizes the PUs’ profit continuously over time. The extracted policy is used by PUs to manage renting the spectrum to SUs and it helps PUs to adapt to the changing network conditions. Performance evaluation of the proposed spectrum trading approach shows that it is able to find the optimal size and price of spectrum for each primary user under different conditions. Moreover, the approach constitutes a framework for studying, synthesizing and optimizing other schemes. Another contribution is proposing a new distributed algorithm to manage spectrum sharing among PUs. In our scheme, PUs exchange channels dynamically based on the availability of neighbor’s idle channels. In our cooperative scheme, the objective of spectrum sharing is to maximize the total revenue and utilize spectrum efficiently. Compared to the poverty-line heuristic that does not consider the availability of unused spectrum, our scheme has the advantage of utilizing spectrum efficiently.

  14. Statistics of Lyapunov exponent spectrum in randomly coupled Kuramoto oscillators.

    Science.gov (United States)

    Patra, Soumen K; Ghosh, Anandamohan

    2016-03-01

    Characterization of spatiotemporal dynamics of coupled oscillatory systems can be done by computing the Lyapunov exponents. We study the spatiotemporal dynamics of randomly coupled network of Kuramoto oscillators and find that the spectral statistics obtained from the Lyapunov exponent spectrum show interesting sensitivity to the coupling matrix. Our results indicate that in the weak coupling limit the gap distribution of the Lyapunov spectrum is Poissonian, while in the limit of strong coupling the gap distribution shows level repulsion. Moreover, the oscillators settle to an inhomogeneous oscillatory state, and it is also possible to infer the random network properties from the Lyapunov exponent spectrum.

  15. Analytic continuation average spectrum method for transport in quantum liquids

    Energy Technology Data Exchange (ETDEWEB)

    Kletenik-Edelman, Orly [School of Chemistry, Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel); Rabani, Eran, E-mail: rabani@tau.ac.il [School of Chemistry, Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel); Reichman, David R. [Department of Chemistry, Columbia University, 3000 Broadway, New York, NY 10027 (United States)

    2010-05-12

    Recently, we have applied the analytic continuation averaged spectrum method (ASM) to calculate collective density fluctuations in quantum liquid . Unlike the maximum entropy (MaxEnt) method, the ASM approach is capable of revealing resolved modes in the dynamic structure factor in agreement with experiments. In this work we further develop the ASM to study single-particle dynamics in quantum liquids with dynamical susceptibilities that are characterized by a smooth spectrum. Surprisingly, we find that for the power spectrum of the velocity autocorrelation function there are pronounced differences in comparison with the MaxEnt approach, even for this simple case of smooth unimodal dynamic response. We show that for liquid para-hydrogen the ASM is closer to the centroid molecular dynamics (CMD) result while for normal liquid helium it agrees better with the quantum mode coupling theory (QMCT) and with the MaxEnt approach.

  16. Glassy Dynamics

    DEFF Research Database (Denmark)

    Jensen, Henrik J.; Sibani, Paolo

    2007-01-01

    The term glassy dynamics is often used to refer to the extremely slow relaxation observed in several types of many component systems. The time span needed to reach a steady, time independent, state will typically be far beyond experimentally accessible time scales. When melted alloys are cooled d...

  17. Standardization of broadband radio access networks

    Science.gov (United States)

    Kruys, Jan; Haine, John

    1998-09-01

    This paper introduces the ETSI Project on Broadband Radio Access Networks (EP-BRAN). BRAN systems will be used for local area applications with limited mobility (HIPERLAN/2); fixed access with area coverage in urban and rural areas (HIPERACCESS); and short range high-speed point-to-point links (HIPERLINK). They will support transport of either IP or ATM protocols, supporting managed quality of service. Such systems are needed to provide access to the future broadband core networks supporting multi-media applications. The paper addresses the motivation and market demand for broadband radio access networks, the objectives and scope of the Project, the operational and technical requirements, the types of networks to be standardized, the scope of the standards, the issue of spectrum and the Project schedule.

  18. Leveraging KPIs to optimize patient-access performance.

    Science.gov (United States)

    2014-12-01

    Monitoring patient access is a dynamic process that requireswell-defined and focused indicators that truly reflect performance. Patient-access metrics can be divided into two distinct categories: strategic measures and operational measures. Once key performance indicators are chosen, improving patient access starts with objectively measuring performance, recognizing improvement opportunities, holding staff accountable, and evaluating progress toward goals.

  19. Multi-redshift limits on the 21cm power spectrum from PAPER

    CERN Document Server

    Pober, Daniel C Jacobs Jonathan C; Aguirre, James E; Ali, Zaki; Bowman, Judd; Bradley, Richard F; Carilli, Chris L; DeBoer, David R; Dexter, Matthew R; Gugliucci, Nicole E; Klima, Pat; Liu, Adrian; MacMahon, Dave H E; Manley, Jason R; Moore, David F; Stefan, Irina I; Walbrugh, William P

    2014-01-01

    The epoch of reionization power spectrum is expected to evolve strongly with redshift, and it is this variation with cosmic history that will allow us to begin to place constraints on the physics of reionization. The primary obstacle to the measurement of the EoR power spectrum is bright foreground emission. We present an analysis of observations from the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) telescope which place new limits on the HI power spectrum over the redshift range of $7.5accessible to the instrument. To suppress foregrounds, we use filtering techniques that take advantage of the large instrumental bandwidth to isolate and suppress foreground leakage into the interesting regions of $k$-space. Our 500 hour integration is the longest such yet recorded and demonstrates this method to a dynamic range of $10^4$. Power spectra at different points across the redshift range r...

  20. Spectrum Measurement and Analysis of TV Band in Support of Cognitive Radio Operation in India

    DEFF Research Database (Denmark)

    Patil, Kishor P.; Skouby, Knud Erik; Prasad, Ramjee

    2013-01-01

    have estimated the spectrum utilization of TV band in Pune, India. We have designed the measurement set up and methodology for the measurement campaign. Our spectrum occupancy analysis provides the realistic view on the spectrum opportunities in India for (i) spectrum refarming of TV band; (ii......) Cognitive Radio operation in TV band. Also we have stressed on the need of quantitative analysis of TVWSs availability and compatibility studies for protection of incumbent services for CR access of TVWSs in India. Also this paper reviews the state-of-the-art in standardization of cognitive access to TVWS....

  1. Spectrum and orbit conservation as a factor in future mobile satellite system design

    Science.gov (United States)

    Bowen, Robert R.

    1990-01-01

    Access to the radio spectrum and geostationary orbit is essential to current and future mobile satellite systems. This access is difficult to obtain for current systems, and may be even more so for larger future systems. In this environment, satellite systems that minimize the amount of spectrum orbit resource required to meet a specific traffic requirement are essential. Several spectrum conservation techniques are discussed, some of which are complementary to designing the system at minimum cost. All may need to be implemented to the limits of technological feasibility if network growth is not to be constrained because of the lack of available spectrum-orbit resource.

  2. World Wide Access: Accessible Web Design.

    Science.gov (United States)

    Washington Univ., Seattle.

    This brief paper considers the application of "universal design" principles to Web page design in order to increase accessibility for people with disabilities. Suggestions are based on the World Wide Web Consortium's accessibility initiative, which has proposed guidelines for all Web authors and federal government standards. Seven guidelines for…

  3. The QCD spectrum with three quark flavors

    CERN Document Server

    Bernard, C; DeGrand, T A; Datta, S; DeTar, C E; Gottlieb, S; Heller, U M; Orginos, K; Sugar, R; Toussaint, D; Bernard, Claude; Burch, Tom; Grand, Thomas A. De; Datta, Saumen; Tar, Carleton De; Gottlieb, Steven; Heller, Urs M.; Orginos, Kostas; Sugar, Robert; Toussaint, Doug

    2001-01-01

    We present results from a lattice hadron spectrum calculation using three flavors of dynamical quarks - two light and one strange, and quenched simulations for comparison. These simulations were done using a one-loop Symanzik improved gauge action and an improved Kogut-Susskind quark action. The lattice spacings, and hence also the physical volumes, were tuned to be the same in all the runs to better expose differences due to flavor number. Lattice spacings were tuned using the static quark potential, so as a byproduct we obtain updated results for the effect of sea quarks on the static quark potential. We find indications that the full QCD meson spectrum is in better agreement with experiment than the quenched spectrum. For the 0++ (a0) meson we see a coupling to two pseudoscalar mesons, or a meson decay on the lattice.

  4. Access Nets: Modeling Access to Physical Spaces

    Science.gov (United States)

    Frohardt, Robert; Chang, Bor-Yuh Evan; Sankaranarayanan, Sriram

    Electronic, software-managed mechanisms using, for example, radio-frequency identification (RFID) cards, enable great flexibility in specifying access control policies to physical spaces. For example, access rights may vary based on time of day or could differ in normal versus emergency situations. With such fine-grained control, understanding and reasoning about what a policy permits becomes surprisingly difficult requiring knowledge of permission levels, spatial layout, and time. In this paper, we present a formal modeling framework, called AccessNets, suitable for describing a combination of access permissions, physical spaces, and temporal constraints. Furthermore, we provide evidence that model checking techniques are effective in reasoning about physical access control policies. We describe our results from a tool that uses reachability analysis to validate security policies.

  5. A survey of spectrum prediction methods in cognitive radio networks

    Science.gov (United States)

    Wu, Jianwei; Li, Yanling

    2017-04-01

    Spectrum prediction technology is an effective way to solve the problems of processing latency, spectrum access, spectrum collision and energy consumption in cognitive radio networks. Spectral prediction technology is divided into three categories according to its nature, namely, spectral prediction method based on regression analysis, spectrum prediction method based on Markov model and spectrum prediction method based on machine learning. By analyzing and comparing the three kinds of prediction models, the author hopes to provide some reference for the later researchers. In this paper, the development situation, practical application and existent problems of three kinds of forecasting models are analyzed and summarized. On this basis, this paper discusses the development trend of the next step.

  6. Attack Prevention for Collaborative Spectrum Sensing in Cognitive Radio Networks

    CERN Document Server

    Duan, Lingjie; Huang, Jianwei; Shin, Kang G

    2011-01-01

    Collaborative spectrum sensing can significantly improve the detection performance of secondary unlicensed users (SUs). However, the performance of collaborative sensing is vulnerable to sensing data falsification attacks, where malicious SUs (attackers) submit manipulated sensing reports to mislead the fusion center's decision on spectrum occupancy. Moreover, attackers may not follow the fusion center's decision regarding their spectrum access. This paper considers a challenging attack scenario where multiple rational attackers overhear all honest SUs' sensing reports and cooperatively maximize attackers' aggregate spectrum utilization. We show that, without attack-prevention mechanisms, honest SUs are unable to transmit over the licensed spectrum, and they may further be penalized by the primary user for collisions due to attackers' aggressive transmissions. To prevent such attacks, we propose two novel attack-prevention mechanisms with direct and indirect punishments. The key idea is to identify collisions...

  7. OPTIMIZATION OF SPECTRUM UTILIZATION IN COGNITIVE RADIO SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Li Hongjiang; Zhu Qi

    2011-01-01

    In Cognitive Radio (CR) networks,CR user has to detect the spectrum channel periodically to make sure that the channel is idle during data transmission frame in order to avoid the collisions to the primary users.Hence recent research has been focused on the interference avoidance problem.Quality of Service (QoS) requirement of CR user will affect the time of data transmission in each frame.In this paper,in order to solve the interference avoidance and spectrum utilization problems without cooperation among CR users,a new scheme to obtain the optimal duration of data transmission frame is proposed to maximize the spectrum utilization and guarantee the protection to the primary users.The main advantages of our proposed scheme include the followings:(1) QoS requirement of CR user is concerned; (2) p-persistent Media Access Control (MAC) random access is used to avoid the collisions among CR users; (3) CR network system capacity is considered.We develop a Markov chain of the primary spectrum channel states and an exponential distribution of the CR user's traffic model to analyze the performance of our proposed scheme.Computer simulation shows that there is an optimal data transmission time to maximize the spectrum utilization.However,the regulatory constraint of the collision rate to the primary users has to be satisfied at the expense of spectrum utilization.And also the tradeoff between the spectrum utilization and the capacity of the CR system is taken into account.

  8. Professional Access 2013 programming

    CERN Document Server

    Hennig, Teresa; Hepworth, George; Yudovich, Dagi (Doug)

    2013-01-01

    Authoritative and comprehensive coverage for building Access 2013 Solutions Access, the most popular database system in the world, just opened a new frontier in the Cloud. Access 2013 provides significant new features for building robust line-of-business solutions for web, client and integrated environments.  This book was written by a team of Microsoft Access MVPs, with consulting and editing by Access experts, MVPs and members of the Microsoft Access team. It gives you the information and examples to expand your areas of expertise and immediately start to develop and upgrade projects. Exp

  9. Rising expectations: access to biomedical information.

    Science.gov (United States)

    Lindberg, D A B; Humphreys, B L

    2008-01-01

    To provide an overview of the expansion in public access to electronic biomedical information over the past two decades, with an emphasis on developments to which the U.S. National Library of Medicine contributed. Review of the increasingly broad spectrum of web-accessible genomic data, biomedical literature, consumer health information, clinical trials data, and images. The amount of publicly available electronic biomedical information has increased dramatically over the past twenty years. Rising expectations regarding access to biomedical information were stimulated by the spread of the Internet, the World Wide Web, advanced searching and linking techniques. These informatics advances simplified and improved access to electronic information and reduced costs, which enabled inter-organizational collaborations to build and maintain large international information resources and also aided outreach and education efforts The demonstrated benefits of free access to electronic biomedical information encouraged the development of public policies that further increase the amount of information available. Continuing rapid growth of publicly accessible electronic biomedical information presents tremendous opportunities and challenges, including the need to ensure uninterrupted access during disasters or emergencies and to manage digital resources so they remain available for future generations.

  10. Cause of winter gravity wave spectrum saturation

    Institute of Scientific and Technical Information of China (English)

    WU; Yongfu; XU; Jiyao

    2005-01-01

    This paper utilizes horizontal velocity measurements observed from 19 chaff rockets and nearly simultaneous temperature measurements collected from 19 falling sphere rockets to study the cause of winter gravity wave spectrum saturation. Results suggest that strong horizontal velocity shears larger than 0.04 s-1 are observed to be present at various heights near the winter mesopause. On one single chaff rocket flight, an extremely strong horizontal velocity shear as high as 0.33 s-1 is observed at 87.4 km and is believed to be the strongest value ever measured in the mesosphere. These strong horizontal velocity shears, together with Brunt-V(a)is(a)l(a) frequency squared obtained from the temperature profile, act collectively to yield two dynamical instability regions of Richardson number smaller than 1/4, suggesting that the saturated gravity wave spectrum observed by the chaff rockets in winter is a result of dynamical instability.

  11. Perti Net-Based Workflow Access Control Model

    Institute of Scientific and Technical Information of China (English)

    陈卓; 骆婷; 石磊; 洪帆

    2004-01-01

    Access control is an important protection mechanism for information systems. This paper shows how to make access control in workflow system. We give a workflow access control model (WACM) based on several current access control models. The model supports roles assignment and dynamic authorization. The paper defines the workflow using Petri net. It firstly gives the definition and description of the workflow, and then analyzes the architecture of the workflow access control model (WACM). Finally, an example of an e-commerce workflow access control model is discussed in detail.

  12. 同步扫描光谱方法研究聚合物结晶动力学过程%Polymer Crystallization Dynamics Investigated by Synchronous Scanning Spectrum

    Institute of Scientific and Technical Information of China (English)

    罗伟昂; 程玲; 戴李宗; 陈旭东; 麦堪成; 陈钰杰; 廖正福

    2014-01-01

    固体表面反射光与其折射指数之间存在余弦函数关系,而折射指数的均方起伏又和固体表面的密度和浓度起伏有关。因此从反射光的变化可以反映材料内部结构的一些变化。基于此理论指导,本文利用同步扫描光谱(SSS )方法,即荧光光谱仪的同步扫描模式进行反射光的检测,成功地监测了聚己内酯(PCL )薄膜在铜片上的熔融和非等温结晶过程。PCL薄膜的SSS谱图出现了两个明显的荧光光谱仪的光源峰(467和473 nm ),利用这两个峰的信息可以表征聚合物的熔融和结晶过程中分子链结构的变化。采用SSS方法表征分析得到了PCL的热动力学和结晶动力学参数,其结晶Avrami exponent n为2.8~3.2,平均值为3.1,表明PCL的非等温结晶遵循异相成核、三维球晶生长机理。这些与差示扫描量热仪(DSC)得到的参数一致。研究结果表明SSS方法是一种简单、有效的原位测试聚合物熔融和结晶动态过程的方法。此外,SSS方法是一种基于荧光光谱仪的具有普适性的光谱方法,对发光和不发光固态聚合物均可以检测研究。%There is a cosine function between the reflected light intensity of a solid surface and its refractive in-dex .And the mean squared fluctuation of refractive index is related to fluctuation of density and concentration . So some internal structures changes of materials can be reflected by changes in reflected light .Based on this theory ,the synchronous scanning spectrum (SSS) technique was successfully applied to monitor melting and nonisothermal melt-crystallization of poly (ε-caprolactone) (PCL ) film on a copper substrate .SSS can be im-plemented on a spectrofluorimeter by simultaneously scanning the excitation and emission monochromators (i .e .Δλ=λex -λem =0 nm) .In SSS of PCL films ,two dominant peaks correlated to the light source spectrum of the spectrofluorimeter (at 467 and 473

  13. Water accessibility in a membrane-inserting peptide comparing Overhauser DNP and pulse EPR methods

    Science.gov (United States)

    Segawa, Takuya F.; Doppelbauer, Maximilian; Garbuio, Luca; Doll, Andrin; Polyhach, Yevhen O.; Jeschke, Gunnar

    2016-05-01

    Water accessibility is a key parameter for the understanding of the structure of biomolecules, especially membrane proteins. Several experimental techniques based on the combination of electron paramagnetic resonance (EPR) spectroscopy with site-directed spin labeling are currently available. Among those, we compare relaxation time measurements and electron spin echo envelope modulation (ESEEM) experiments using pulse EPR with Overhauser dynamic nuclear polarization (DNP) at X-band frequency and a magnetic field of 0.33 T. Overhauser DNP transfers the electron spin polarization to nuclear spins via cross-relaxation. The change in the intensity of the 1H NMR spectrum of H2O at a Larmor frequency of 14 MHz under a continuous-wave microwave irradiation of the nitroxide spin label contains information on the water accessibility of the labeled site. As a model system for a membrane protein, we use the hydrophobic α-helical peptide WALP23 in unilamellar liposomes of DOPC. Water accessibility measurements with all techniques are conducted for eight peptides with different spin label positions and low radical concentrations (10-20 μM). Consistently in all experiments, the water accessibility appears to be very low, even for labels positioned near the end of the helix. The best profile is obtained by Overhauser DNP, which is the only technique that succeeds in discriminating neighboring positions in WALP23. Since the concentration of the spin-labeled peptides varied, we normalized the DNP parameter ɛ, being the relative change of the NMR intensity, by the electron spin concentration, which was determined from a continuous-wave EPR spectrum.

  14. Molecular Dynamics and Protein Function

    National Research Council Canada - National Science Library

    M. Karplus; J. Kuriyan; Bruce J. Berne

    2005-01-01

    .... Molecular dynamics simulations provide powerful tools for the exploration of the conformational energy landscape accessible to these molecules, and the rapid increase in computational power coupled...

  15. Design for Accessibility

    DEFF Research Database (Denmark)

    Herriott, Richard

    2012-01-01

    A report on how nine rail builder, operators and transport designers deal with design for accessibility......A report on how nine rail builder, operators and transport designers deal with design for accessibility...

  16. Ontology Based Access Control

    Directory of Open Access Journals (Sweden)

    Özgü CAN

    2010-02-01

    Full Text Available As computer technologies become pervasive, the need for access control mechanisms grow. The purpose of an access control is to limit the operations that a computer system user can perform. Thus, access control ensures to prevent an activity which can lead to a security breach. For the success of Semantic Web, that allows machines to share and reuse the information by using formal semantics for machines to communicate with other machines, access control mechanisms are needed. Access control mechanism indicates certain constraints which must be achieved by the user before performing an operation to provide a secure Semantic Web. In this work, unlike traditional access control mechanisms, an "Ontology Based Access Control" mechanism has been developed by using Semantic Web based policies. In this mechanism, ontologies are used to model the access control knowledge and domain knowledge is used to create policy ontologies.

  17. Physical Access Control Database -

    Data.gov (United States)

    Department of Transportation — This data set contains the personnel access card data (photo, name, activation/expiration dates, card number, and access level) as well as data about turnstiles and...

  18. Attack-Tolerant Cooperative Spectrum Sensing Algorithm for Faded and Low-Power Primary User Signal Detection Over Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Mohammad Akbari

    2015-03-01

    Full Text Available Cognitive radio (CR is a novel scheme that is proposed recently to overcome the spectrum scarcity problem in wireless networks through dynamic spectrum access techniques. In this realm, detection of the legitimate users, called primary user (PU, is a primary mission that must be done carefully to prohibit causing any confliction. PU detection in low signal to noise ratio (SNR regime is one of the main challenges of CR users that measure the energy level of the PU for sensing the spectrum. This process will be more complicated when the SNR fluctuations due to wireless channel effects are taking into accounts. Another source of ambiguity is the false sensing data that might be reported by malfunctioning or malicious secondary nodes, the so called spectrum sensing data falsification attackers (SSDF. This paper utilizes the potential benefits of cooperative spectrum sensing method in a way that it can become applicable when the CR nodes encounter wireless channel uncertainty and (or some CR nodes that behave maliciously. To this end, the estimated PU-signal and channel statistics are employed to determine the likelihood of CR sensing reports in a MAP hypothesis test scheme for decision about channel occupancy. Also, in order to determine the trustworthiness of each CR-user's data and eliminate the effect of SSDF attackers, a computational trust evaluation algorithm is proposed that is based on the resolved likelihood of CR sensing reports

  19. Access Control Enforcement Testing

    OpenAIRE

    El Kateb, Donia; Elrakaiby, Yehia; Mouelhi, Tejeddine; Le Traon, Yves

    2012-01-01

    A policy-based access control architecture com- prises Policy Enforcement Points (PEPs), which are modules that intercept subjects access requests and enforce the access decision reached by a Policy Decision Point (PDP), the module implementing the access decision logic. In applications, PEPs are generally implemented manually, which can introduce errors in policy enforcement and lead to security vulnerabilities. In this paper, we propose an approach to systematically test and validate the co...

  20. Compressive Sensing for Spread Spectrum Receivers

    DEFF Research Database (Denmark)

    Fyhn, Karsten; Jensen, Tobias Lindstrøm; Larsen, Torben

    2013-01-01

    With the advent of ubiquitous computing there are two design parameters of wireless communication devices that become very important: power efficiency and production cost. Compressive sensing enables the receiver in such devices to sample below the Shannon-Nyquist sampling rate, which may lead...... to a decrease in the two design parameters. This paper investigates the use of Compressive Sensing (CS) in a general Code Division Multiple Access (CDMA) receiver. We show that when using spread spectrum codes in the signal domain, the CS measurement matrix may be simplified. This measurement scheme, named...... Compressive Spread Spectrum (CSS), allows for a simple, effective receiver design. Furthermore, we numerically evaluate the proposed receiver in terms of bit error rate under different signal to noise ratio conditions and compare it with other receiver structures. These numerical experiments show that though...

  1. Sinclair ZX Spectrum.

    Science.gov (United States)

    Rodwell, Peter

    1982-01-01

    Describes and evaluates the hardware, software, peripheral devices, performance capabilities, and programing capacity of the Sinclair ZX Spectrum microcomputer. The computer's display system, its version of the BASIC programing language, its graphics capabilities, and the unique features of its data entry keyboard are discussed. (JL)

  2. Autism Spectrum Disorder (ASD)

    Science.gov (United States)

    ... with: 1 Communication and interaction with other people Restricted interests and repetitive behaviors Different people with autism can have different symptoms. For this reason, autism is known as a spectrum disorder —which means that there is a range of ...

  3. Autism Spectrum Disorder

    Centers for Disease Control (CDC) Podcasts

    2014-04-02

    This podcast discusses autism spectrum disorder (ASD), a developmental disability that causes problems with social, communication, and behavioral skills. CDC estimates that one in 68 children has been identified as having ASD.  Created: 4/2/2014 by National Center on Birth Defects and Developmental Disabilities (NCBDDD).   Date Released: 4/2/2014.

  4. What is a Spectrum?

    CERN Document Server

    Bolton, Adam S; Brownstein, Joel; Pandey, Parul; Schlegel, David; Shu, Yiping

    2011-01-01

    This contribution describes the "spectro-perfectionism" algorithm of Bolton & Schlegel (2010, PASP, 122, 248) that is being implemented within the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III (SDSS-III), in terms of its potential to deliver Poisson-limited sky subtraction and lossless compression of the input spectrum likelihood functional given raw CCD data.

  5. Battlefield spectrum management

    Science.gov (United States)

    Sivakumar, C.

    1997-06-01

    Modern tactical communications systems rely on radios to support network and user connectivity. One of the challenges for network planners and managers is to make best use of scarce and vulnerable frequency spectrum resources to support the communication needs of war fighters. With the wide variety of Iris radio types typically to be deployed in the battlefield (ranging from high frequency to super high frequency), a comprehensive suite of tools is necessary to ensure that frequency interference is kept minimum. Without a sophisticated frequency spectrum management system, the most advanced tactical communications systems could be rendered useless, jeopardizing human life and national security. For these reasons, it is important to develop an Iris wide battlefield spectrum management capability that takes full advantage of current frequency spectrum management research and development (R&D), related tools, and supporting technology for assigning frequencies. This session briefly describes various assignment strategies being adopted in the Iris BFSM for overcoming cosite/collocated/farsite interferences along with the propagation models [from high frequency (HF) to super high frequency (SHF)] used for the assignment of frequencies. Also a brief thread outlining the process for generating frequency allocation/assignment request and analysis of frequency interference is discussed.

  6. Information and image integration: project spectrum

    Science.gov (United States)

    Blaine, G. James; Jost, R. Gilbert; Martin, Lori; Weiss, David A.; Lehmann, Ron; Fritz, Kevin

    1998-07-01

    The BJC Health System (BJC) and the Washington University School of Medicine (WUSM) formed a technology alliance with industry collaborators to develop and implement an integrated, advanced clinical information system. The industry collaborators include IBM, Kodak, SBC and Motorola. The activity, called Project Spectrum, provides an integrated clinical repository for the multiple hospital facilities of the BJC. The BJC System consists of 12 acute care hospitals serving over one million patients in Missouri and Illinois. An interface engine manages transactions from each of the hospital information systems, lab systems and radiology information systems. Data is normalized to provide a consistent view for the primary care physician. Access to the clinical repository is supported by web-based server/browser technology which delivers patient data to the physician's desktop. An HL7 based messaging system coordinates the acquisition and management of radiological image data and sends image keys to the clinical data repository. Access to the clinical chart browser currently provides radiology reports, laboratory data, vital signs and transcribed medical reports. A chart metaphor provides tabs for the selection of the clinical record for review. Activation of the radiology tab facilitates a standardized view of radiology reports and provides an icon used to initiate retrieval of available radiology images. The selection of the image icon spawns an image browser plug-in and utilizes the image key from the clinical repository to access the image server for the requested image data. The Spectrum system is collecting clinical data from five hospital systems and imaging data from two hospitals. Domain specific radiology imaging systems support the acquisition and primary interpretation of radiology exams. The spectrum clinical workstations are deployed to over 200 sites utilizing local area networks and ISDN connectivity.

  7. 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.

  8. Spread Spectrum Techniques and their Applications to Wireless Communications

    DEFF Research Database (Denmark)

    Prasad, Ramjee; Cianca, E.

    2005-01-01

    Spread Spectrum (SS) radio communications is on the verge of potentially explosive commercial development An SS-based multiple access, such as CDMA, has been chosen for 3G wireless communications. Other current applications of SS techniues are in Wireless LANs and Satellite Navigation Systems...

  9. Spread Spectrum Techniques and their Applications to Wireless Communications

    DEFF Research Database (Denmark)

    Prasad, Ramjee; Cianca, E.

    2005-01-01

    Spread Spectrum (SS) radio communications is on the verge of potentially explosive commercial development An SS-based multiple access, such as CDMA, has been chosen for 3G wireless communications. Other current applications of SS techniues are in Wireless LANs and Satellite Navigation Systems. Ho...

  10. Comorbid Social Anxiety Disorder in Adults with Autism Spectrum Disorder

    Science.gov (United States)

    Maddox, Brenna B.; White, Susan W.

    2015-01-01

    Social anxiety symptoms are common among cognitively unimpaired youth with autism spectrum disorder (ASD). Few studies have investigated the co-occurrence of social anxiety disorder (SAD) in adults with ASD, although identification may aid access to effective treatments and inform our scientific efforts to parse heterogeneity. In this preliminary…

  11. Pro Access 2010 Development

    CERN Document Server

    Collins, Mark

    2011-01-01

    Pro Access 2010 Development is a fundamental resource for developing business applications that take advantage of the features of Access 2010 and the many sources of data available to your business. In this book, you'll learn how to build database applications, create Web-based databases, develop macros and Visual Basic for Applications (VBA) tools for Access applications, integrate Access with SharePoint and other business systems, and much more. Using a practical, hands-on approach, this book will take you through all the facets of developing Access-based solutions, such as data modeling, co

  12. Access 2013 for dummies

    CERN Document Server

    Ulrich Fuller, Laurie

    2013-01-01

    The easy guide to Microsoft Access returns with updates on the latest version! Microsoft Access allows you to store, organize, view, analyze, and share data; the new Access 2013 release enables you to build even more powerful, custom database solutions that integrate with the web and enterprise data sources. Access 2013 For Dummies covers all the new features of the latest version of Accessand serves as an ideal reference, combining the latest Access features with the basics of building usable databases. You'll learn how to create an app from the Welcome screen, get support

  13. Android Access Control Extension

    Directory of Open Access Journals (Sweden)

    Anton Baláž

    2015-12-01

    Full Text Available The main objective of this work is to analyze and extend security model of mobile devices running on Android OS. Provided security extension is a Linux kernel security module that allows the system administrator to restrict program's capabilities with per-program profiles. Profiles can allow capabilities like network access, raw socket access, and the permission to read, write, or execute files on matching paths. Module supplements the traditional Android capability access control model by providing mandatory access control (MAC based on path. This extension increases security of access to system objects in a device and allows creating security sandboxes per application.

  14. Educational and Behavioral Interventions in Management of Autism Spectrum Disorder.

    Science.gov (United States)

    Sengupta, Koyeli; Lobo, Leera; Krishnamurthy, Vibha

    2017-01-01

    The increasing prevalence of autism spectrum disorder (ASD) makes early recognition, evaluation and management an important task for pediatricians, physicians and other professionals caring for children. Educational interventions form the mainstay of management for children with autism spectrum disorder. Such interventions focus on improving social interaction, communication and challenging behaviors, thereby promoting learning and independence in children. This article provides an overview of educational and behavioral interventions in autism spectrum disorder, with special reference to challenges and feasible solutions in the Indian context. Articles were retrieved from various databases including Google Scholar, Medscape, Cochrane, PubMed using the search terms 'autism spectrum disorder OR autism AND educational interventions'; 'autism spectrum disorder OR autism, educational interventions AND India' and 'autism spectrum disorder OR autism AND India'. Reference lists from retrieved articles as well as websites of organizations working in this space in India were also searched. Extracted manuscripts were analysed for content related to various aspects of educational and behavioral interventions in autism spectrum disorder. Intervention models for autism spectrum disorder are based on various theoretical orientations and target specific deficits associated with the disorder. In addition, evidence-based principles for effective intervention are highlighted. In developing countries like India, access to interventions is a challenge and resources are limited. In such settings, the pediatrician's or physician's role is vital in supporting families choose programs that are evidence-based, target individual needs and result in improved outcomes.

  15. Urban Railway Accessibility

    Institute of Scientific and Technical Information of China (English)

    GUAN Hongzhi; YIN Yuanfei; YAN Hai; HAN Yan; QIN Huanmei

    2007-01-01

    Effective use of urban rapid railway systems requires that the railway systems be effectively connected with other transportation modes so that they are accessible. This paper uses the logit model and data to analyze the factors influencing railway access choices in a railway choice access model. The results indicate that access time, access cost, and access distance are factors significantly affecting railway access choices. The user's income significantly affects the probability of choosing to walk rather than to take a taxi,but is not related to choosing buses or bicycles. Vehicle ownership significantly affects the probability of choosing a taxi, but is not significantly related to the other modes. The conclusions provide an analysis tool for urban railway planning and construction.

  16. Open Access @ DTU

    DEFF Research Database (Denmark)

    Ekstrøm, Jeannette

    Open Access is high on the agenda in Denmark and internationally. Denmark has announced a national strategy for Open Access that aims to achieve Open Access to 80% in 2017 and 100% in 2022 to peer review research articles. All public Danish funders as well as H2020 requires that all peer review...... articles that is an outcome of their funding will be Open Access. Uploading your full texts (your final author manuscript after review ) to DTU Orbit is a fundamental part of providing Open Access to your research. We are here to answer all your questions with regards to Open Access and related topics...... such as copyright, DTU Orbit, Open Access journals, APCs, Vouchers etc....

  17. PERFORMANCE OPTIMIZATION OF COGNITIVE RADIO WITH WIDEBAND SPECTRUM SENSING

    Directory of Open Access Journals (Sweden)

    E. Saraniya

    2014-09-01

    Full Text Available Cognitive radio (CR technology allows the unlicensed user to access the licensed spectrum bands. Spectrum sensing is an essential function in cognitive radio to detect the spectrum holes and opportunistically use the underutilized frequency bands without causing interference to primary user (PU. In this paper we are maximizing the throughput capacity of cognitive radio user and hence the performance of spectrum sensing and protection to licensed user improves over a wideband spectrum sensing band. The simulation of cognitive radio is done by analyzing the performance of energy detector spectrum sensing technique to detect primary user and to formulate the optimization using multiband joint detection method (MJD to achieve suitable trade- off between secondary user access and primary user network. The main aim of this paper is to maximize the probability of detection and to decrease the probabilities of miss detection and false alarm. To maximize the throughput it requires minimizing the throughput loss caused by miss detection and the significant reduction in probability of false alarm helps in achieving the spectral efficiency from the secondary user’s perspective. The simulation results show that the performance increases with the MJD method.

  18. RAP Framework for Spectrum Management in Cognitive Radio

    Directory of Open Access Journals (Sweden)

    Kishore V. Krishnan

    2014-03-01

    Full Text Available The Spectrum Management schemes currently in use overlook the need for interference measurements at the receiver end. The negligence culminates in an underwhelming performance of the Cognitive Radio Network (CRN due to the presence of hidden/exposed primary senders. Our aim was to implement the RAP framework for spectrum management in a cognitive Radio. The scheme chosen deems it a necessity to take into consideration the inaccuracy of spectrum sensing in order to achieve the desired optimal performance. Unlike the widely used schemes which solely depend on local interference measurements, the proposed probabilistic framework aims at enhancing the CRN good put by incorporating interference measurements performed at the receiver into the protocol. Moreover, the spectrum management scheme, discussed in the study, makes most of the least exploitable spectral opportunities by relying on low power rate communication robust to interference. The issued spectrum access policy ensures fair distribution of spectral opportunity to its multiple secondary users. It, in contrast to the existing greedy spectrum access policies, prevents any user from monopolizing the available spectral opportunity as it is regulated and operated in a strictly probabilistic framework. It also diligently makes useful, provisions in the policy to ensure that every spectral opportunity, even while being exploited, appear available at all times to see to it that no Secondary User (SU misidentifies the spectral opportunity as unavailable.

  19. Cognitive Medium Access: Exploration, Exploitation and Competition

    CERN Document Server

    Lai, Lifeng; Jiang, Hai; Poor, H Vincent

    2007-01-01

    This paper establishes the equivalence between cognitive medium access and the competitive multi-armed bandit problem. First, the scenario in which a single cognitive user wishes to opportunistically exploit the availability of empty frequency bands in the spectrum with multiple bands is considered. In this scenario, the availability probability of each channel is unknown to the cognitive user a priori. Hence efficient medium access strategies must strike a balance between exploring the availability of other free channels and exploiting the opportunities identified thus far. By adopting a Bayesian approach for this classical bandit problem, the optimal medium access strategy is derived and its underlying recursive structure is illustrated via examples. To avoid the prohibitive computational complexity of the optimal strategy, a low complexity asymptotically optimal strategy is developed. The proposed strategy does not require any prior statistical knowledge about the traffic pattern on the different channels....

  20. Raman spectrum of asphaltene

    KAUST Repository

    Abdallah, Wael A.

    2012-11-05

    Asphaltenes extracted from seven different crude oils representing different geological formations from around the globe were analyzed using the Raman spectroscopic technique. Each spectrum is fitted with four main peaks using the Gaussian function. On the basis of D1 and G bands of the Raman spectrum, asphaltene indicated an ordered structure with the presence of boundary defected edges. The average aromatic sheet size of the asphaltene molecules is estimated within the range of 1.52-1.88 nm, which represents approximately seven to eight aromatic fused rings. This estimation is based on the integrated intensity of D1 and G bands, as proposed by Tunistra and Koenig. The results here are in perfect agreement with so many other used techniques and indicate the potential applicability of Raman measurements to determine the average aromatic ring size and its boundary. © 2012 American Chemical Society.

  1. The Supersymmetric Particle Spectrum

    CERN Document Server

    Barger, V; Ohmann, P

    1994-01-01

    We examine the spectrum of supersymmetric particles predicted by grand unified theoretical (GUT) models where the electroweak symmetry breaking is accomplished radiatively. We evolve the soft supersymmetry breaking parameters according to the renormalization group equations (RGE). The minimization of the Higgs potential is conveniently described by means of tadpole diagrams. We present complete one-loop expressions for these minimization conditions, including contributions from the matter and the gauge sectors. We concentrate on the low $\\tan \\beta$ fixed point region (that provides a natural explanation of a large top quark mass) for which we find solutions to the RGE satisfying both experimental bounds and fine-tuning criteria. We also find that the constraint from the consideration of the lightest supersymmetric particle as the dark matter of the universe is accommodated in much of parameter space where the lightest neutralino is predominantly gaugino. The supersymmetric mass spectrum displays correlations...

  2. [Clinical spectrum of neuroborreliosis].

    Science.gov (United States)

    Owecki, Michał K; Kozubski, Wojciech

    2007-01-01

    Lyme disease is a multisystem infectious disease with a wide variety of symptoms involving the skin as well as nervous, musculosceletal and cardiovascular systems. Lyme disease is caused by spirochaete Borrelia burgdorferi transmitted by Ixodes tics in endemic regions. The diverse manifestations of neuroborreliosis require it to be included in differential diagnosis of many neurological disorders. The paper reviews the spectrum of clinical symptoms of nervous system involvement in early and late Lyme disease.

  3. AUTISM SPECTRUM DISORDERS (ASD)

    OpenAIRE

    Middha Akanksha; Kataria Sahil; Sandhu Premjeet; Kapoor Bhawna

    2011-01-01

    Autism or Autism Spectrum Disorders (ASD) is a serious neurological disorder affecting communication skills, social interactions, adaptability in an individual, and also causes dramatic changes in behavioral patterns. This condition typically lasts throughout one’s lifetime and affects both, children as well as adults. Research has shown a tenfold increase in autism cases over the past decade and still rising at an alarming pace. The origins of autism are not known even to modern science. Aut...

  4. Unified Framework Towards Flexible Multiple Access Schemes for 5G

    Institute of Scientific and Technical Information of China (English)

    SUN Qi; WANG Sen; HAN Shuangfeng; Chih Lin I

    2016-01-01

    Non⁃orthogonal multiple access (NOMA) schemes have achieved great attention recently and been considered as a crucial compo⁃nent for 5G wireless networks since they can efficiently enhance the spectrum efficiency, support massive connections and poten⁃tially reduce access latency via grant free access. In this paper, we introduce the candidate NOMA solutions in 5G networks, com⁃paring the principles, key features, application scenarios, transmitters and receivers, etc. In addition, a unified framework of these multiple access schemes are proposed to improve resource utilization, reduce the cost and support the flexible adaptation of multi⁃ple access schemes. Further, flexible multiple access schemes in 5G systems are discussed. They can support diverse deployment scenarios and traffic requirements in 5G. Challenges and future research directions are also highlighted to shed some lights for the standardization in 5G.

  5. An orthogonal spectrum sharing scheme for wireless sensor networks

    Directory of Open Access Journals (Sweden)

    Pandharipande Ashish

    2011-01-01

    Full Text Available Abstract It is not economically viable to allocate a dedicated spectrum band to wireless sensor networks (WSNs. Moreover, sharing a spectrum band with incumbent (primary system compromises the reliability and performance of both the systems due to interference from one system to another. In this article, we address this limitation by proposing a two-phase orthogonal spectrum sharing protocol for a WSN which exploits multiple sensor nodes to effectively cancel out the interference from a WSN to the primary system, and vice versa. As a consequence, it is possible to achieve spectrum access for the WSN without compromising on the performance of either systems. Performance of WSN as well as the primary system is quantified in terms of average received signal to noise ratio. We then validate the efficiency of the proposed scheme through analytical and simulation results.

  6. Port Access Cardiac Surgery.

    Science.gov (United States)

    Viganó, Mario; Minzioni, Gaetano; Spreafico, Patrizio; Rinaldi, Mauro; Pasquino, Stefano; Ceriana, Piero; Locatelli, Alessandro

    2000-10-01

    The port-access technique for cardiac surgery was recently developed at Stanford University in California as a less invasive method to perform some cardiac operations. The port-access system has been described in detail elsewhere. It is based on femoral arterial and venous access for cardiopulmonary bypass (CPB) and on the adoption of a specially designed triple-lumen catheter described originally by Peters, and subsequently modified and developed in the definitive configuration called the endoaortic clamp.

  7. Are PDF Documents Accessible?

    Directory of Open Access Journals (Sweden)

    Mireia Ribera Turró

    2008-09-01

    Full Text Available Adobe PDF is one of the most widely used formats in scientific communications and in administrative documents. In its latest versions it has incorporated structural tags and improvements that increase its level of accessibility. This article reviews the concept of accessibility in the reading of digital documents and evaluates the accessibility of PDF according to the most widely established standards.

  8. Access Data Analysis Cookbook

    CERN Document Server

    Bluttman, Ken

    2008-01-01

    This book offers practical recipes to solve a variety of common problems that users have with extracting Access data and performing calculations on it. Whether you use Access 2007 or an earlier version, this book will teach you new methods to query data, different ways to move data in and out of Access, how to calculate answers to financial and investment issues, how to jump beyond SQL by manipulating data with VBA, and more.

  9. Accessible e-learning

    OpenAIRE

    Bühler, Christian; Scheer, Birgit

    2005-01-01

    People with disabilities often encounter difficulties while trying to learn something, because teaching material is for example not accessible to blind people or rooms, where courses take place, are not accessible to people using a wheelchair. E-learning provides an opportunity to disabled people. With the new German law on the equalisation of opportunities for people with disabilities for the first time access to information technology was explicitly taken up in German legislation. As a cons...

  10. Hybrid spread spectrum radio system

    Science.gov (United States)

    Smith, Stephen F [London, TN; Dress, William B [Camas, WA

    2010-02-09

    Systems and methods are described for hybrid spread spectrum radio systems. A method, includes receiving a hybrid spread spectrum signal including: fast frequency hopping demodulating and direct sequence demodulating a direct sequence spread spectrum signal, wherein multiple frequency hops occur within a single data-bit time and each bit is represented by chip transmissions at multiple frequencies.

  11. Spectrum of classes of point emitters of electromagnetic wave fields.

    Science.gov (United States)

    Castañeda, Román

    2016-09-01

    The spectrum of classes of point emitters has been introduced as a numerical tool suitable for the design, analysis, and synthesis of non-paraxial optical fields in arbitrary states of spatial coherence. In this paper, the polarization state of planar electromagnetic wave fields is included in the spectrum of classes, thus increasing its modeling capabilities. In this context, optical processing is realized as a filtering on the spectrum of classes of point emitters, performed by the complex degree of spatial coherence and the two-point correlation of polarization, which could be implemented dynamically by using programmable optical devices.

  12. OGIS Access System

    Data.gov (United States)

    National Archives and Records Administration — The OGIS Access System (OAS) provides case management, stakeholder collaboration, and public communications activities including a web presence via a web portal.

  13. Open Access Policy

    OpenAIRE

    University of East London, .

    2013-01-01

    The University of East London is committed to and supports open access to its research publications.\\ud There is a worldwide move towards free and unrestricted access to research publications, with benefits\\ud for researchers, universities and wider society. UEL supports this initiative and recognises the\\ud importance of open access in increasing the visibility and impact of research. This policy is aligned with\\ud and supports HEFCE’s Policy for Open Access in the Post‐2014 REF, and is alig...

  14. Channel Access in Erlang

    Energy Technology Data Exchange (ETDEWEB)

    Nicklaus, Dennis J. [Fermilab

    2013-10-13

    We have developed an Erlang language implementation of the Channel Access protocol. Included are low-level functions for encoding and decoding Channel Access protocol network packets as well as higher level functions for monitoring or setting EPICS process variables. This provides access to EPICS process variables for the Fermilab Acnet control system via our Erlang-based front-end architecture without having to interface to C/C++ programs and libraries. Erlang is a functional programming language originally developed for real-time telecommunications applications. Its network programming features and list management functions make it particularly well-suited for the task of managing multiple Channel Access circuits and PV monitors.

  15. Web Accessibility and Guidelines

    Science.gov (United States)

    Harper, Simon; Yesilada, Yeliz

    Access to, and movement around, complex online environments, of which the World Wide Web (Web) is the most popular example, has long been considered an important and major issue in the Web design and usability field. The commonly used slang phrase ‘surfing the Web’ implies rapid and free access, pointing to its importance among designers and users alike. It has also been long established that this potentially complex and difficult access is further complicated, and becomes neither rapid nor free, if the user is disabled. There are millions of people who have disabilities that affect their use of the Web. Web accessibility aims to help these people to perceive, understand, navigate, and interact with, as well as contribute to, the Web, and thereby the society in general. This accessibility is, in part, facilitated by the Web Content Accessibility Guidelines (WCAG) currently moving from version one to two. These guidelines are intended to encourage designers to make sure their sites conform to specifications, and in that conformance enable the assistive technologies of disabled users to better interact with the page content. In this way, it was hoped that accessibility could be supported. While this is in part true, guidelines do not solve all problems and the new WCAG version two guidelines are surrounded by controversy and intrigue. This chapter aims to establish the published literature related to Web accessibility and Web accessibility guidelines, and discuss limitations of the current guidelines and future directions.

  16. Access 2013 bible

    CERN Document Server

    Alexander, Michael

    2013-01-01

    A comprehensive reference to the updated and new features of Access 2013 As the world's most popular database management tool, Access enables you to organize, present, analyze, and share data as well as build powerful database solutions. However, databases can be complex. That's why you need the expert guidance in this comprehensive reference. Access 2013 Bible helps you gain a solid understanding of database purpose, construction, and application so that whether you're new to Access or looking to upgrade to the 2013 version, this well-rounded resource provides you with a th

  17. 基于活动授权的组合Web服务业务流程动态访问控制模型研究%STUDY ON ACTIVITY AUTHORIZATION BASED DYNAMIC ACCESS CONTROL MODEL FOR COMPOSITE WEB SERVICES BUSINESS PROCESS

    Institute of Scientific and Technical Information of China (English)

    上超望; 刘清堂; 赵呈领; 童名文

    2014-01-01

    Business process access control mechanism is a difficult problem in composite web services security applications.Considering the deficiency in current researches,an Activity Authorization Based Dynamic Access Control Model for BPEL4WS (AACBP)is proposed.By dissolving the coupling relationship between the organization model and the business process model,AACBP utilizes activity authorization as the basic unit to implement BPEL4WS access control.Through the activity instances,the model implements fine-gained access control of the activities,and realizes the synchronization of authorization and business process execution.At last,the paper also describes the implementa-tion architecture of AACBP model in web services secure composition.%业务流程访问控制机制是组合Web服务安全应用中的难点问题。针对现有研究不足,提出基于活动授权的Web服务业务流程动态访问控制模型AACBP(Activity Authorization Based Dynamic Access Control Model for BPEL4WS)。通过解除组织模型和业务流程模型间的耦合关系,AACBP将活动授权作为BPEL4WS(Business Process Expression Language for Web Services)活动访问控制实施的基本单元。依据活动实例动态感知上下文,AACBP细粒度约束活动访问授权,实现授权流与业务流程执行同步。最后给出AACBP模型在Web服务安全组合中的实施机制。

  18. Tracing molecular dynamics at the femto-/atto-second boundary through extreme-ultraviolet pump-probe spectroscopy

    CERN Document Server

    Carpeggiani, P A; Palacios, A; Gray, D; Martín, F; Charalambidis, D

    2013-01-01

    Coherent light pulses of few to hundreds of femtoseconds (fs) duration have prolifically served the field of ultrafast phenomena. While fs pulses address mainly dynamics of nuclear motion in molecules or lattices in the gas, liquid or condensed matter phase, the advent of attosecond pulses has in recent years provided direct experimental access to ultrafast electron dynamics. However, there are processes involving nuclear motion in molecules and in particular coupled electronic and nuclear motion that possess few fs or even sub-fs dynamics. In the present work we have succeeded in addressing simultaneously vibrational and electronic dynamics in molecular Hydrogen. Utilizing a broadband extreme-ultraviolet (XUV) continuum the entire, Frank-Condon allowed spectrum of H2 is coherently excited. Vibrational, electronic and ionization 1fs scale dynamics are subsequently tracked by means of XUV-pump-XUV-probe measurements. These reflect the intrinsic molecular behavior as the XUV probe pulse hardly distorts the mole...

  19. Writing Instruction for Students with Autism Spectrum Disorders: A Review of Literature

    Science.gov (United States)

    Pennington, Robert C.; Delano, Monica E.

    2012-01-01

    Historically, learners with autism spectrum disorders (ASD) have not had access to the general education curriculum. Current legislation mandates that "all" children, including children with ASD, have access to and make progress in the general education curriculum. This article contains a review of the literature on writing instruction for…

  20. Writing Instruction for Students with Autism Spectrum Disorders: A Review of Literature

    Science.gov (United States)

    Pennington, Robert C.; Delano, Monica E.

    2012-01-01

    Historically, learners with autism spectrum disorders (ASD) have not had access to the general education curriculum. Current legislation mandates that "all" children, including children with ASD, have access to and make progress in the general education curriculum. This article contains a review of the literature on writing instruction for…