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Sample records for precoded lte multiuser

  1. Adaptive Precoded MIMO for LTE Wireless Communication

    NASA Astrophysics Data System (ADS)

    Nabilla, A. F.; Tiong, T. C.

    2015-04-01

    Long-Term Evolution (LTE) and Long Term Evolution-Advanced (ATE-A) have provided a major step forward in mobile communication capability. The objectives to be achieved are high peak data rates in high spectrum bandwidth and high spectral efficiencies. Technically, pre-coding means that multiple data streams are emitted from the transmit antenna with independent and appropriate weightings such that the link throughput is maximized at the receiver output thus increasing or equalizing the received signal to interference and noise (SINR) across the multiple receiver terminals. However, it is not reliable enough to fully utilize the information transfer rate to fit the condition of channel according to the bandwidth size. Thus, adaptive pre-coding is proposed. It applies pre-coding matrix indicator (PMI) channel state making it possible to change the pre-coding codebook accordingly thus improving the data rate higher than fixed pre-coding.

  2. Precoding Method Interference Management for Quasi-EVD Channel

    PubMed Central

    Song, Wei; Song, Sang Seob

    2014-01-01

    The Cholesky decomposition-block diagonalization (CD-BD) interference alignment (IA) for a multiuser multiple input multiple output (MU-MIMO) relay system is proposed, which designs precoders for the multiple access channel (MAC) by employing the singular value decomposition (SVD) as well as the mean square error (MSE) detector for the broadcast Hermitian channel (BHC) taken advantage of in our design. Also, in our proposed CD-BD IA algorithm, the relaying function is made use to restructure the quasieigenvalue decomposition (quasi-EVD) equivalent channel. This approach used for the design of BD precoding matrix can significantly reduce the computational complexity and proposed algorithm can address several optimization criteria, which is achieved by designing the precoding matrices in two steps. In the first step, we use Cholesky decomposition to maximize the sum-of-rate (SR) with the minimum mean square error (MMSE) detection. In the next step, we optimize the system BER performance with the overlap of the row spaces spanned by the effective channel matrices of different users. By iterating the closed form of the solution, we are able not only to maximize the achievable sum-of-rate (ASR), but also to minimize the BER performance at a high signal-to-noise ratio (SNR) region. PMID:25258731

  3. Key Enabling Physical Layer Technologies for LTE-Advanced

    NASA Astrophysics Data System (ADS)

    Jiang, Meilong; Prasad, Narayan; Xin, Yan; Yue, Guosen; Khojastepour, Amir; Liu, Le; Inoue, Takamichi; Koyanagi, Kenji; Kakura, Yoshikazu

    The 3GPP Long Term Evolution Advanced (LTE-A) system, as compared to the LTE system, is anticipated to include several new features and enhancements, such as the usage of channel bandwidth beyond 20MHz (up 100MHz), higher order multiple input multiple output (MIMO) for both downlink and uplink transmissions, larger capacity especially for cell edge user equipment, and voice over IP (VoIP) users, and wider coverage and etc. This paper presents some key enabling technologies including flexible uplink access schemes, advanced uplink MIMO receiver designs, cell search, adaptive hybrid ARQ, and multi-resolution MIMO precoding, for the LTE-A system.

  4. MIMO Precoding for Networked Control Systems with Energy Harvesting Sensors

    NASA Astrophysics Data System (ADS)

    Cai, Songfu; Lau, Vincent K. N.

    2016-09-01

    In this paper, we consider a MIMO networked control system with an energy harvesting sensor, where an unstable MIMO dynamic system is connected to a controller via a MIMO fading channel. We focus on the energy harvesting and MIMO precoding design at the sensor so as to stabilize the unstable MIMO dynamic plant subject to the energy availability constraint at the sensor. Using the Lyapunov optimization approach, we propose a closed-form dynamic energy harvesting and dynamic MIMO precoding solution, which has an event-driven control structure. Furthermore, the MIMO precoding solution is shown to have an eigenvalue water-filling structure, where the water level depends on the state estimation covariance, energy queue and the channel state, and the sea bed level depends on the state estimation covariance. The proposed scheme is also compared with various baselines and we show that significant performance gains can be achieved.

  5. Multi-use lunar telescopes

    NASA Technical Reports Server (NTRS)

    Genet, Russell M.; Genet, David R.; Talent, David L.; Drummond, Mark; Hine, Butler P.; Boyd, Louis J.; Trueblood, Mark

    1992-01-01

    The objective of multi-use telescopes is to reduce the initial and operational costs of space telescopes to the point where a fair number of telescopes, a dozen or so, would be affordable. The basic approach is to develop a common telescope, control system, and power and communications subsystem that can be used with a wide variety of instrument payloads, i.e., imaging CCD cameras, photometers, spectrographs, etc. By having such a multi-use and multi-user telescope, a common practice for earth-based telescopes, development cost can be shared across many telescopes, and the telescopes can be produced in economical batches.

  6. Multi-use lunar telescopes

    NASA Technical Reports Server (NTRS)

    Drummond, Mark; Hine, Butler; Genet, Russell; Genet, David; Talent, David; Boyd, Louis; Trueblood, Mark; Filippenko, Alexei V. (Editor)

    1991-01-01

    The objective of multi-use telescopes is to reduce the initial and operational costs of space telescopes to the point where a fair number of telescopes, a dozen or so, would be affordable. The basic approach is to develop a common telescope, control system, and power and communications subsystem that can be used with a wide variety of instrument payloads, i.e., imaging CCD cameras, photometers, spectrographs, etc. By having such a multi-use and multi-user telescope, a common practice for earth-based telescopes, development cost can be shared across many telescopes, and the telescopes can be produced in economical batches.

  7. LTE turbo decoder design

    NASA Astrophysics Data System (ADS)

    Le, Yang; Tianchun, Ye; Bin, Wu; Ruiqi, Zhang

    2015-07-01

    This paper presents a turbo decoder supporting all 188 block sizes in 3GPP long term evolution (LTE) standard which can be employed in the LTE micro-eNodB system. The design allows 1, 2, 4, 8 or 16 soft-in/soft-out (SISO) decoders to concurrently process each block size, and the number of iterations can be adjusted. By adding a register in core structure add-compare-select-add, this article proposes an improved SISO algorithm and interleaving design, calculated forward state matrix and backward state matrix alternately, and the branch transition probability can be used in the Turbo decode process directly just after one clock delay. The structure enables a decoder processing radix-2 algorithm with high speed, instead of radix-4 as the conventional decoder. Moreover, the paper details an interleaver/de-interleaver, which is combined by two operational steps. One is column address mapping and the other is intra-row permutation. Decoder realizes interleaving by loading data from memories whose address is generated by column mapping and then lets data passing through inter-row permutation. For de-interleaving, the system can adopt reverse operation. Project supported by the LTE-Advanced User Equipment Software Baseband Technology Major Project of China (No. 2013ZX0300315001).

  8. Low Complexity Turbo Receiver for LTE Uplink with Transmitter IQ Imbalance

    NASA Astrophysics Data System (ADS)

    Liu, Rui; Ding, Lv; Gao, Xi Qi

    In this paper, we investigate two improved turbo receivers for the Long Term Evolution (LTE) uplink in the presence of transmitter (Tx) in-phase and quadrature-phase imbalance (IQI) with parameters known at eNodeB. For multiuser multiple-input multiple-output (MU-MIMO) single-carrier frequency division multiple access (SC-FDMA) systems, we derive a optimal joint linear minimum mean square error (MMSE) turbo multiuser detector (MUD) based on the mirror symmetry clusters. For the single use SC-FDMA system with Tx IQI, we derive an optimal widely linear MMSE (WLMMSE) turbo equalizer. Both receivers are implemented in the discrete frequency domain and only slightly increase the computational complexity compared to the conventional turbo receivers. Monte Carlo simulations show that the proposed receivers significantly outperform the conventional turbo receivers. The simulation results are then confirmed by the extrinsic information transfer (EXIT) chart analysis.

  9. A novel type II relay-assisted retransmission scheme for uplink of LTE-advanced system

    NASA Astrophysics Data System (ADS)

    Li, Anxin; Nagata, Satoshi; Harada, Atsushi; Suda, Hirohito

    2013-12-01

    Relay, which enables coverage extension and throughput enhancement, is a very promising technique for future wireless communication systems. Among different types of relay, type II relay is one kind of inband relays and is hotly discussed in LTE-Advanced system for throughput enhancement. In order to support type II relay, many challenges must be overcome. In this article, we focus on relay-assisted uplink data retransmission and propose a novel joint design of reference signal and data precoding for type II relay. The proposed method not only solves the problem of channel estimation mismatch for control information, but also achieves cooperative diversity gain for data transmission. Simulation results show the effectiveness of the proposed method over existing schemes.

  10. Capacity analysis of threshold-based SNR scheduler in LTE systems

    NASA Astrophysics Data System (ADS)

    Sulyman, Ahmed Iyanda; Ahmad, Ishtiaq; Hassanein, Hossam; Alshebeili, Saleh A.

    2013-12-01

    This paper presents the capacity analysis of a threshold-based SNR scheduler in the long-term evolution (LTE) cellular systems. LTE standard has adopted multiuser OFDMA, and stipulates adjacent subcarrier groupings for mapping the physical OFDM subcarriers into resource blocks that form the basic unit of radio resource management (RRM) in LTE network. The standard however did not specify the details of the RRM algorithm to be employed, leaving this aspect for vendors to differentiate their products. Popular RRM algorithms such as round-robin (RR), proportional fairness (PF), and maximum SNR (MaxSNR), have been implemented recently as operator-selectable options on LTE base station (BS). In this paper, we present a threshold-based SNR scheduler that has the capability of modeling all of the above-mentioned algorithms and thus allows vendors to combine the separate implementations of these algorithms into one generalized scheduling algorithm, where the threshold level used at any time instant defines the scheduling discipline to be realized. We derive the capacity enhancement achievable using the proposed scheduling scheme, and also present system-level simulations to corroborate the analysis. Our analytical and simulation results indicate that the proposed algorithm models the existing ones closely at different values of the threshold. The results also demonstrate the data rate enhancements, and the level of user fairness, achievable in the network for various levels of the threshold.

  11. Performance Analysis for LTE Wireless Communication

    NASA Astrophysics Data System (ADS)

    Tholhath, S.; Tiong, T. C.

    2015-04-01

    Long Term Evolution (LTE) is the new upgrade path for carrier with both GSM/UMTS networks and CDMA2000 networks. The LTE is targeting to become the first global mobile phone standard regardless of the different LTE frequencies and bands use in other countries barrier. Adaptive Modulation and Coding (AMC) is used to increase the network capacity or downlink data rates. Various modulation types are discussed such as Quadrature Phase Shift Keying (QPSK) and Quadrature Amplitude Modulation (QAM). Spatial multiplexing techniques for 4×4 MIMO antenna configurations are considered. This paper has outlined various estimation techniques to increase the throughput of the LTE network by simulating the estimation techniques with various parameters in the LTE downlink mode 4 (spatial multiplexing). Three techniques i.e. channel estimation technique, estimation of channel models and MIMO receiver algorithm are simulated to provide the ideal LTE wireless communication system.

  12. BER analysis of TDD downlink multiuser MIMO systems with imperfect channel state information

    NASA Astrophysics Data System (ADS)

    Zhou, Baolong; Jiang, Lingge; Zhao, Shengjie; He, Chen

    2011-12-01

    In downlink multiuser multiple-input multiple-output (MU-MIMO) systems, the zero-forcing (ZF) transmission is a simple and effective technique for separating users and data streams of each user at the transmitter side, but its performance depends greatly on the accuracy of the available channel state information (CSI) at the transmitter side. In time division duplex (TDD) systems, the base station estimates CSI based on uplink pilots and then uses it through channel reciprocity to generate the precoding matrix in the downlink transmission. Because of the constraints of the TDD frame structure and the uplink pilot overhead, there inevitably exists CSI delay and channel estimation error between CSI estimation and downlink transmission channel, which degrades system performance significantly. In this article, by characterizing CSI inaccuracies caused by CSI delay and channel estimation error, we develop a novel bit error rate (BER) expression for M-QAM signal in TDD downlink MU-MIMO systems. We find that channel estimation error causes array gain loss while CSI delay causes diversity gain loss. Moreover, CSI delay causes more performance degradation than channel estimation error at high signal-to-noise ratio for time varying channel. Our research is especially valuable for the design of the adaptive modulation and coding scheme as well as the optimization of MU-MIMO systems. Numerical simulations show accurate agreement with the proposed analytical expressions.

  13. A Novel Nonlinear Precoding Detection Algorithm for VBLAST in MIMO-MC-CDMA Downlink System

    NASA Astrophysics Data System (ADS)

    Fu, Hongliang; Tao, Yong

    Considering the error propagation effect and high complexity of the Vertical Bell Labs Layered Space Time (V-BLAST), a novel nonlinear ZF-THP algorithm for VBLAST in MIMO-MC-CDMA downlink system is proposed in this paper. QR decomposition is used for precoding matrix, the nonlinear Tomlinson-Harashima Precoding (THP) is used between the sub-carrier channels of MC-CDMA to eliminate interference from other signals at the transmitter, and can obtain frequency diversity gain and eliminate effectively the error propagation effect. At the receiver, zero forcing criterion is used, and the complexity of the receiver can be reduced. Simulation results show that the proposed algorithm is better than the traditional zero forcing algorithm and the linear precoding algorithm in the system BER.

  14. University multi-user facility survey-2010.

    PubMed

    Riley, Melissa B

    2011-12-01

    Multi-user facilities serve as a resource for many universities. In 2010, a survey was conducted investigating possible changes and successful characteristics of multi-user facilities, as well as identifying problems in facilities. Over 300 surveys were e-mailed to persons identified from university websites as being involved with multi-user facilities. Complete responses were received from 36 facilities with an average of 20 years of operation. Facilities were associated with specific departments (22%), colleges (22%), and university research centers (8.3%) or were not affiliated with any department or college within the university (47%). The five most important factors to succeed as a multi-user facility were: 1) maintaining an experienced, professional staff in an open atmosphere; 2) university-level support providing partial funding; 3) broad client base; 4) instrument training programs; and 5) an effective leader and engaged strategic advisory group. The most significant problems were: 1) inadequate university financial support and commitment; 2) problems recovering full service costs from university subsidies and user fees; 3) availability of funds to repair and upgrade equipment; 4) inability to retain highly qualified staff; and 5) unqualified users dirtying/damaging equipment. Further information related to these issues and to fee structure was solicited. Overall, there appeared to be a decline in university support for facilities and more emphasis on securing income by serving clients outside of the institution and by obtaining grants from entities outside of the university. PMID:22131888

  15. Architectures for Developing Multiuser, Immersive Learning Scenarios

    ERIC Educational Resources Information Center

    Nadolski, Rob J.; Hummel, Hans G. K.; Slootmaker, Aad; van der Vegt, Wim

    2012-01-01

    Multiuser immersive learning scenarios hold strong potential for lifelong learning as they can support the acquisition of higher order skills in an effective, efficient, and attractive way. Existing virtual worlds, game development platforms, and game engines only partly cater for the proliferation of such learning scenarios as they are often…

  16. Precoder design for indoor visible light communications with multiple RGB LEDs

    NASA Astrophysics Data System (ADS)

    Gao, Qian; Lang, Tian; Bo, Feng; Chen, Gang; Hua, Yingbo

    2013-09-01

    In this paper, we consider the problem of precoder design for an optical intensity modulation (IM) system with multiple redgreen- blue (RGB) light emitting diodes (LEDs) as transmitters and imaging lens with color filters as receivers. The purpose of using a precoder is to optimally allocate power for each LED based on the current channel condition to minimize the detection error rate. To achieve the goal, an non-convex optimization problem due to a nonconvex constraint is formulated first taking into account several crucial lighting constraints, such as flicker-free, color rendering index (CRI), and luminous efficacy rate (LER) as well as the average optical intensity constraint and non-negative transmitter-side signal constraint. By manipulations we transform the problem into a semi-definite programming (SDP) and by approximation we relaxed the non-convex constraint into a convex one. The resulting convex problem is iteratively solved by CVX, an add-in to MATLAB, which jointly optimizes the precoder and DC-biases driving each LED. We assume that M-PAM signal constellation is used as input to the precoder and an MMSE receiver is applied to recover the input signals in this paper, while our method is not restrict to the specific choice.

  17. Precoder selection scheme based on message-passing approach: a practical perspective

    NASA Astrophysics Data System (ADS)

    Guerreiro, Igor M.; Cavalcante, Charles C.; Hui, Dennis

    2014-10-01

    This work addresses a distributed technique to precoding matrices coordination in a multi-cell network. We propose an iterative method based on a message-passing algorithm in factor graphs. Finite precoder codebooks for different MIMO setups are adopted for beam forming purposes. Conversely, practical cellular networks usually solve the precoder selection problem in a non-iterative manner based on the best response method. Nevertheless, this method may not provide a near-optimal solution. For more realistic results, the wireless channel is modeled based on measured data that comprises spatial correlation effects. Evaluations on the potential of such an approach are provided and its performance is compared with the selfish/greedy approach. The capability of reaching the globally optimal solution is evaluated, as well as its performance per iteration. Simulation results for the precoder selection example are presented and discussed, which show that the graph-based technique generally obtains gain in system capacity over both the non-iterative and selfish approaches. Besides, the proposed method usually reaches the global optima in an efficient manner in terms of signaling load.

  18. The Forgotten Women of Pre-Code: An Annotated Filmography and Bibliography

    ERIC Educational Resources Information Center

    Tang, Jennifer

    2010-01-01

    In recent years, "pre-code" films have been re-discovered and applauded by film scholars and feminists. The term refers to the period between 1929 and 1934 when many Hollywood studios openly disregarded the censorship restrictions of the Hays Code. Named after censorship czar William H. Hays, the Code forbade nudity, cursing, sexual innuendo,…

  19. Precoding techniques for PAPR reduction in asymmetrically clipped OFDM based optical wireless system

    NASA Astrophysics Data System (ADS)

    Ranjha, Bilal; Kavehrad, Mohsen

    2013-01-01

    In this paper, we have analyzed different precoding based Peak-to-Average-Power (PAPR) reduction techniques for asymmetrically-clipped Orthogonal Frequency Division Multiplexing (OFDM) optical wireless communication systems. Intensity Modulated Direct Detection (IM/DD) technique is among the popular techniques for optical wireless communication systems. OFDM cannot be directly applied to IM systems because of the bipolar nature of the output signal. Therefore some variants of OFDM systems have been proposed for (IM/DD) optical wireless systems. Among them are DC-biased-OFDM, Asymmetrically-Clipped Optical OFDM (ACO-OFDM) [2] and Pulse Amplitude Modulated Discrete Multitone (PAM-DMT) [3]. Both ACO-OFDM and PAM-DMT require low average power and thus are very attractive for optical wireless systems. OFDM systems suffer from high PAPR problem that can limit its performance due to non-linear characteristics of LED. Therefore PAPR reduction techniques have to be employed. This paper analyzes precoding based PAPR reduction methods for ACO-OFDM and PAM-DMT. We have used Discrete Fourier Transform (DFT) coding, Zadoff-Chu Transform (ZCT) [8] and Discrete Cosine Transform (DCT) for ACOOFDM and only DCT for PAM-DMT since the modulating symbols are real. We have compared the performance of these precoding techniques using different QAM modulation schemes. Simulation results have shown that both DFT and ZCT offer more PAPR reduction than DCT in ACO-OFDM. For PAM-DMT, DCT precoding yields significant PAPR reduction compared to conventional PAM-DMT signal. These precoding schemes also offer the advantage of zero signaling overhead.

  20. Departures from LTE in Cool Stars

    NASA Astrophysics Data System (ADS)

    Mashonkina, L.

    2010-11-01

    Departures from LTE may significantly affect determinations of stellar parameters and chemical abundances of cool stars, in particular, metal-poor stars. We review the application of the non-LTE ionization equilibrium between Ca i and Ca ii to constrain the surface gravity of very metal-poor and hyper metal-poor stars spectroscopically. The few examples from Galactic chemical evolution studies show that our understanding of how nucleosynthesis proceeds throughout Galactic history depends on the accuracy of spectral line formation modelling. Problems of non-LTE modelling of Fe i- Fe ii are also discussed. This research was supported by the Deutsche Forschungsgemeinschaft with grant 436 RUS 17/13/07 and by the Russian Foundation for Basic Research with grant 05-02-39005-GFEN-a.

  1. Deviations from LTE in a stellar atmosphere

    NASA Technical Reports Server (NTRS)

    Kalkofen, W.; Klein, R. I.; Stein, R. F.

    1979-01-01

    Deviations for LTE are investigated in an atmosphere of hydrogen atoms with one bound level, satisfying the equations of radiative, hydrostatic, and statistical equilibrium. The departure coefficient and the kinetic temperature as functions of the frequency dependence of the radiative cross section are studied analytically and numerically. Near the outer boundary of the atmosphere, the departure coefficient is smaller than unity when the radiative cross section grows with frequency faster than with the square of frequency; it exceeds unity otherwise. Far from the boundary the departure coefficient tends to exceed unity for any frequency dependence of the radiative cross section. Overpopulation always implies that the kinetic temperature in the statistical-equilibrium atmosphere is higher than the temperature in the corresponding LTE atmosphere. Upper and lower bounds on the kinetic temperature are given for an atmosphere with deviations from LTE only in the optically shallow layers when the emergent intensity can be described by a radiation temperature.

  2. PRECO-D2: program for calculating preequilibrium and direct reaction double differential cross sections

    SciTech Connect

    Kalbach, C.

    1985-02-01

    The code PRECO-D2 uses the exciton model for preequilibrium nuclear reactions to describe the emission of particles with mass numbers of 1 to 4 from an equilibrating composite nucleus. A distinction is made between open and closed configurations in this system and between the multi-step direct (MSD) and multi-step compound (MSC) components of the preequilibrium cross section. Additional MSD components are calculated semi-empirically to account for direct nucleon transfer reactions and direct knockout processes involving cluster degrees of freedom. Evaporation from the equilibrated composite nucleus is included in the full MSC cross section. Output of energy differential and double differential cross sections is provided for the first particle emitted from the composite system. Multiple particle emission is not considered. This report describes the reaction models used in writing PRECO-D2 and explains the organization and utilization of the code. 21 refs.

  3. Grouped DCT precoding for PAPR reduction in optical direct detection OFDM systems

    NASA Astrophysics Data System (ADS)

    Wang, Zhong-peng; Zhang, Shao-zhong

    2013-05-01

    A new grouped precoding technique based on discrete cosine transform (DCT) is presented for peak to average power ratio (PAPR) reduction of optical intensity modulated/direct detection (IM/DD) orthogonal frequency division multiplexing (OFDM) system. The computational complexity of the scheme is reduced by at least about 15% compared with that of the ordinary DCT precoding scheme when the number of groups is 2. The PAPR with this method can be reduced by about 0.8 dB. Meantime, compared with original OFDM, the bit error rate (BER) performance of system is improved. So the proposed scheme for reducing PAPR is very effective in optical IM/DD OFDM systems.

  4. Hadamard precoding for PAPR reduction in optical direct detection OFDM systems

    NASA Astrophysics Data System (ADS)

    Wang, Zhong-Peng; Xiao, Jiang-Nan; Li, Fan; Chen, Lin

    2011-09-01

    The high peak-to-average power ration (PAPR) values of optical orthogond frequency division multiplexing (OFDM) signal limit the system nonlinear tolerance (NLT). In this paper, a novel method based on Hadamard precoding is proposed to reduce the peak-to-average power ratio in optical direct detection OFDM system. The proposed scheme is successfully applied to an experimental system of optical direct-detection OFDM signal transmission through fiber. In this experiment, the 2.5 Gbit/s binary phase shift keying (BPSK) optical OFDM signals with Hadamard precoding are generated and transmitted though a single mode fiber. The experimental results show that the proposed scheme can reduce PAPR by almost 1.5 dB. Meantime the received sensitivity is improved by 2 dB with 100 km fiber transmission compared with that of an ordinary optical direct detection OFDM system.

  5. 'LTE-diffusion approximation' for arc calculations

    NASA Astrophysics Data System (ADS)

    Lowke, J. J.; Tanaka, M.

    2006-08-01

    This paper proposes the use of the 'LTE-diffusion approximation' for predicting the properties of electric arcs. Under this approximation, local thermodynamic equilibrium (LTE) is assumed, with a particular mesh size near the electrodes chosen to be equal to the 'diffusion length', based on De/W, where De is the electron diffusion coefficient and W is the electron drift velocity. This approximation overcomes the problem that the equilibrium electrical conductivity in the arc near the electrodes is almost zero, which makes accurate calculations using LTE impossible in the limit of small mesh size, as then voltages would tend towards infinity. Use of the LTE-diffusion approximation for a 200 A arc with a thermionic cathode gives predictions of total arc voltage, electrode temperatures, arc temperatures and radial profiles of heat flux density and current density at the anode that are in approximate agreement with more accurate calculations which include an account of the diffusion of electric charges to the electrodes, and also with experimental results. Calculations, which include diffusion of charges, agree with experimental results of current and heat flux density as a function of radius if the Milne boundary condition is used at the anode surface rather than imposing zero charge density at the anode.

  6. Coexistence of 3G Repeaters with LTE Base Stations

    PubMed Central

    Yeo, Woon-Young

    2013-01-01

    Repeaters have been an attractive solution for mobile operators to upgrade their wireless networks at low cost and to extend network coverage effectively. Since the first LTE commercial deployment in 2009, many mobile operators have launched LTE networks by upgrading their 3G and legacy networks. Because all 3G frequency bands are shared with the frequency bands for LTE deployment and 3G mobile operators have an enormous number of repeaters, reusing 3G repeaters in LTE networks is definitely a practical and cost-efficient solution. However, 3G repeaters usually do not support spatial multiplexing with multiple antennas, and thus it is difficult to reuse them directly in LTE networks. In order to support spatial multiplexing of LTE, the role of 3G repeaters should be replaced with small LTE base stations or MIMO-capable repeaters. In this paper, a repeater network is proposed to reuse 3G repeaters in LTE deployment while still supporting multilayer transmission of LTE. Interestingly, the proposed network has a higher cluster throughput than an LTE network with MIMO-capable repeaters. PMID:24459420

  7. Multi-use crops and botanochemical production

    SciTech Connect

    Bagby, M.O.; Buchanan, R.A.; Otey, F.H.

    1981-01-01

    Oil- and hydrocarbon-producing plants are especially attractive as future energy and chemical resources. Plants already supply several products competitive with synthetic petrochemicals. These products include tall oil, naval stores, seed oils, and plant oils. For this discussion, we refer to such products collectively as oils and hydrocarbons. For many years, the US Department of Agriculture has actively pursued a multi-disciplined approach to identify and establish new crops as renewable resources. Patterned after the Department's program to identify annually renewable fibrous plants that could be cultivated for papermaking, an analytical screening program was instituted in 1974 to identify and evaluate species as sources of multi-use oil- and hydrocarbon-producing crops for food material and energy production. The multi-use concept requires plant breeders and agronomists to deal with a variety of new crops, each yielding several different products of varying economic value. In screening plant species as potential crops, a rating system was employed that emphasized potential economy of plant production, total biomass yield, and oil and hydrocarbon content. Subsequently, all candidates were ranked by this rating system. It should be emphasized that vigorous perennials were given preference over annuals, with the concept that seed-bed preparation would be infrequent for perennials. Data for over 300 species have been accumulated, and about 40 species have been identified that have sufficient potential to merit further consideration. Nearly all of these species are being further investigated by USDA plant scientists; meanwhile, the screening program continues.

  8. Performance of TCP variants over LTE network

    NASA Astrophysics Data System (ADS)

    Nor, Shahrudin Awang; Maulana, Ade Novia

    2016-08-01

    One of the implementation of a wireless network is based on mobile broadband technology Long Term Evolution (LTE). LTE offers a variety of advantages, especially in terms of access speed, capacity, architectural simplicity and ease of implementation, as well as the breadth of choice of the type of user equipment (UE) that can establish the access. The majority of the Internet connections in the world happen using the TCP (Transmission Control Protocol) due to the TCP's reliability in transmitting packets in the network. TCP reliability lies in the ability to control the congestion. TCP was originally designed for wired media, but LTE connected through a wireless medium that is not stable in comparison to wired media. A wide variety of TCP has been made to produce a better performance than its predecessor. In this study, we simulate the performance provided by the TCP NewReno and TCP Vegas based on simulation using network simulator version 2 (ns2). The TCP performance is analyzed in terms of throughput, packet loss and end-to-end delay. In comparing the performance of TCP NewReno and TCP Vegas, the simulation result shows that the throughput of TCP NewReno is slightly higher than TCP Vegas, while TCP Vegas gives significantly better end-to-end delay and packet loss. The analysis of throughput, packet loss and end-to-end delay are made to evaluate the simulation.

  9. Zero Forcing Conditions for Nonlinear channel Equalisation using a pre-coding scheme

    SciTech Connect

    Arfa, Hichem; Belghith, Safya; El Asmi, Sadok

    2009-03-05

    This paper shows how we can present a zero forcing conditions for a nonlinear channel equalisation. These zero forcing conditions based on the rank of nonlinear system are issued from an algebraic approach based on the module theoretical approach, in which the rank of nonlinear channel is clearly defined. In order to improve the performance of equalisation and reduce the complexity of used nonlinear systems, we will apply a pre-coding scheme. Theoretical results are given and computer simulation is used to corroborate the theory.

  10. Clique-Based Neural Associative Memories with Local Coding and Precoding.

    PubMed

    Mofrad, Asieh Abolpour; Parker, Matthew G; Ferdosi, Zahra; Tadayon, Mohammad H

    2016-08-01

    Techniques from coding theory are able to improve the efficiency of neuroinspired and neural associative memories by forcing some construction and constraints on the network. In this letter, the approach is to embed coding techniques into neural associative memory in order to increase their performance in the presence of partial erasures. The motivation comes from recent work by Gripon, Berrou, and coauthors, which revisited Willshaw networks and presented a neural network with interacting neurons that partitioned into clusters. The model introduced stores patterns as small-size cliques that can be retrieved in spite of partial error. We focus on improving the success of retrieval by applying two techniques: doing a local coding in each cluster and then applying a precoding step. We use a slightly different decoding scheme, which is appropriate for partial erasures and converges faster. Although the ideas of local coding and precoding are not new, the way we apply them is different. Simulations show an increase in the pattern retrieval capacity for both techniques. Moreover, we use self-dual additive codes over field [Formula: see text], which have very interesting properties and a simple-graph representation. PMID:27348736

  11. Photonic RF vector signal generation with enhanced spectral efficiency using precoded double single-sideband modulation.

    PubMed

    Wang, Yuanquan; Chien, Hung-Chang; Guo, HaiChao; Yu, Jianjun; Chang, Gee-Kung; Chi, Nan

    2016-06-01

    In this study, a novel photonic vector signal at frequency (RF) bands generation scheme based on the beating of double single sidebands (SSBs) is proposed and experimentally demonstrated. The double SSBs carry separate constant- or multi-amplitude quadrature-amplitude-modulation vector signals are generated from a single I/Q modulator. By adopting phase and amplitude precoding, different constellations can be generated, such as 3-ary phase-shift keying (PSK), 4-PSK, 7-PSK, 8-PSK, and so on. In this work, 10-Gbaud 7-PSK vector signal generation at 20 GHz enabled by two precoded 4-PSK SSB signals via a single I/Q modulator is theoretically and experimentally investigated. Compared to a single-drive Mach-Zehnder modulator or conventional I/Q modulator-based photonic vector signal generation scheme, the spectrum efficiency can be doubled. Differential coding is also implemented at the transmitter side for accurate demodulation of 7-PSK into two 4-PSK signals. The bit-error ratio for 10-Gbaud 7-PSK vector signals can be under hard-decision forward-error-correction threshold of 3.8×10-3 after 10 km standard single-mode fiber transmission. PMID:27244413

  12. Multiuser Collaboration with Networked Mobile Devices

    NASA Technical Reports Server (NTRS)

    Tso, Kam S.; Tai, Ann T.; Deng, Yong M.; Becks, Paul G.

    2006-01-01

    In this paper we describe a multiuser collaboration infrastructure that enables multiple mission scientists to remotely and collaboratively interact with visualization and planning software, using wireless networked personal digital assistants(PDAs) and other mobile devices. During ground operations of planetary rover and lander missions, scientists need to meet daily to review downlinked data and plan science activities. For example, scientists use the Science Activity Planner (SAP) in the Mars Exploration Rover (MER) mission to visualize downlinked data and plan rover activities during the science meetings [1]. Computer displays are projected onto large screens in the meeting room to enable the scientists to view and discuss downlinked images and data displayed by SAP and other software applications. However, only one person can interact with the software applications because input to the computer is limited to a single mouse and keyboard. As a result, the scientists have to verbally express their intentions, such as selecting a target at a particular location on the Mars terrain image, to that person in order to interact with the applications. This constrains communication and limits the returns of science planning. Furthermore, ground operations for Mars missions are fundamentally constrained by the short turnaround time for science and engineering teams to process and analyze data, plan the next uplink, generate command sequences, and transmit the uplink to the vehicle [2]. Therefore, improving ground operations is crucial to the success of Mars missions. The multiuser collaboration infrastructure enables users to control software applications remotely and collaboratively using mobile devices. The infrastructure includes (1) human-computer interaction techniques to provide natural, fast, and accurate inputs, (2) a communications protocol to ensure reliable and efficient coordination of the input devices and host computers, (3) an application

  13. Transport and radiation in complex LTE mixtures

    NASA Astrophysics Data System (ADS)

    Janssen, Jesper; Peerenboom, Kim; Suijker, Jos; Gnybida, Mykhailo; van Dijk, Jan

    2014-10-01

    Complex LTE mixtures are for example encountered in re-entry, welding, spraying and lighting. These mixtures typically contain a rich chemistry in combination with large temperature gradients. LTE conditions are also interesting because they can aid in the validation of NLTE algorithms. An example is the calculation of transport properties. In this work a mercury free high intensity discharge lamp is considered. The investigation focusses on using salts like InI or SnI as a buffer species. By using these species a dominant background gas like mercury is no longer present. As a consequence the diffusion algorithms based on Fick's law are no longer applicable and the Stefan-Maxwell equations must be solved. This system of equations is modified with conservation rules to set a coldspot pressure for saturated species and enforce the mass dosage for unsaturated species. The radiative energy transport is taken into account by raytracing. Quantum mechanical simulations have been used to calculate the potential curves and the transition dipole moments for indium with iodine and tin with iodine. The results of these calculations have been used to predict the quasistatic broadening by iodine. The work was supported by the project SCHELP from the Belgium IWT (Project Number 110003) and the CATRENE SEEL Project (CA502).

  14. Quantum cryptography on multiuser optical fibre networks

    NASA Astrophysics Data System (ADS)

    Townsend, Paul D.

    1997-01-01

    To establish a secure communication channel, it is necessary to distribute between two users a key which allows safe encryption and decryption of messages. But because decryption is a simple task for any key holder, it is crucial that the key remains secret during distribution. Secrecy cannot be guaranteed if distribution occurs on the basis of classical physical mechanisms, as it is impossible to know whether the key has been intercepted during transmission. Quantum cryptography1-3 provides a fundamental solution to this problem. When quantum-mechanical processes are used to establish the key, any eavesdropping during transmission leads to an unavoidable and detectable disturbance in the received key information. Quantum cryptography has been demonstrated using standard telecommunication fibres linking single pairs of users4-8, but practical implementations will require communication networks with many users9. Here I introduce a practical scheme for multi-user quantum cryptography, and demonstrate its operation on an optical fibre network. The scheme enables a single controller on the network to establish, and regularly update, a distinct secret key with each network user. These keys can then be used to securely encrypt conventional data transmissions that are broadcast on the network.

  15. Cost Effectiveness of Home Energy Retrofits in Pre-Code Vintage Homes in the United States

    SciTech Connect

    Fairey, Philip

    2012-11-01

    This analytical study examines the opportunities for cost-effective energy efficiency and renewable energy retrofits in residential archetypes constructed prior to 1980 (Pre-Code) in fourteen U.S. cities. These fourteen cities are representative of each of the International Energy Conservation Code (IECC) climate zones in the contiguous United States. The analysis is conducted using an in-house version of EnergyGauge USA v.2.8.05 named CostOpt that has been programmed to perform iterative, incremental economic optimization on a large list of residential energy efficiency and renewable energy retrofit measures. The principle objectives of the study are to determine the opportunities for cost effective source energy reductions in this large cohort of existing residential building stock as a function of local climate and energy costs; and to examine how retrofit financing alternatives impact the source energy reductions that are cost effectively achievable.

  16. LTE plasma reactors for materials conversion

    NASA Astrophysics Data System (ADS)

    Kolacinski, Zbigniew; Szymanski, Lukasz; Raniszewski, Grzegorz

    2013-02-01

    Plasma aided materials conversion is the use of charged particles for producing new materials with unusual and superior properties or to convert unwanted materials such as waste into environmentally friendly products. The near LTE plasma (in atmospheric or reduced pressure) is a nice tool for engineering of materials which in consequence upgrades the performance of most of the consumer goods. The paper presents a few samples of the own research results related to the design and use of some plasma reactors for synthesis of nanomaterials and hazardous materials destruction with their conversion into valuable products. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.

  17. Non-LTE Gas in Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Gusev, O. A.; Kutepov, A. A.

    2003-01-01

    The new model of radiative cooling/heating of the mesosphere and lower thermosphere (MLT) in the ro-vibrational bands of atmospheric gases (CO2, O3, H2O, CO, NO, N2O and others) accounts for vibrational and rotational non-LTE, line-overlapping, and absorption and transformation of the near-infrared solar radiation. The model utilizes ALI technique for the solution of the system of kinetic equations and the DFE radiative transfer algorithm. The contributions of various band to the total cooling/heating are analyzed. The model is applied to the calculation of the MLT cooling/heating for atmospheric data retrieved from the CRISTA limb radiance measurements. Implications for modeling of the MLT region are discussed.

  18. W-band OFDM photonic vector signal generation employing a single Mach-Zehnder modulator and precoding.

    PubMed

    Xiao, Jiangnan; Li, Xinying; Xu, Yuming; Zhang, Ziran; Chen, Long; Yu, Jianjun

    2015-09-01

    We present a simple radio-over-fiber (RoF) link architecture for millimeter-wave orthogonal frequency division multiplexing (OFDM) transmission using only one Mach-Zehnder modulator (MZM) and precoding technique. In the transmission system, the amplitudes and the phase of the driving radio-frequency (RF) OFDM signal on each sub-carrier are precoded, to ensure that the OFDM signal after photodetector (PD) can be restored to original OFDM signal. The experimental results show that the bit-error ratios (BERs) of the transmission system are less than the forward-error-correction (FEC) threshold of 3.8 × 10(-3), which demonstrates that the generation of OFDM vector signal based on our proposed scheme can be employed in our system architecture. PMID:26368494

  19. Location-assured, multifactor authentication on smartphones via LTE communication

    NASA Astrophysics Data System (ADS)

    Kuseler, Torben; Lami, Ihsan A.; Al-Assam, Hisham

    2013-05-01

    With the added security provided by LTE, geographical location has become an important factor for authentication to enhance the security of remote client authentication during mCommerce applications using Smartphones. Tight combination of geographical location with classic authentication factors like PINs/Biometrics in a real-time, remote verification scheme over the LTE layer connection assures the authenticator about the client itself (via PIN/biometric) as well as the client's current location, thus defines the important aspects of "who", "when", and "where" of the authentication attempt without eaves dropping or man on the middle attacks. To securely integrate location as an authentication factor into the remote authentication scheme, client's location must be verified independently, i.e. the authenticator should not solely rely on the location determined on and reported by the client's Smartphone. The latest wireless data communication technology for mobile phones (4G LTE, Long-Term Evolution), recently being rolled out in various networks, can be employed to enhance this location-factor requirement of independent location verification. LTE's Control Plane LBS provisions, when integrated with user-based authentication and independent source of localisation factors ensures secure efficient, continuous location tracking of the Smartphone. This feature can be performed during normal operation of the LTE-based communication between client and network operator resulting in the authenticator being able to verify the client's claimed location more securely and accurately. Trials and experiments show that such algorithm implementation is viable for nowadays Smartphone-based banking via LTE communication.

  20. Optimal space-time precoding of artificial sensory feedback through mutichannel microstimulation in bi-directional brain-machine interfaces

    NASA Astrophysics Data System (ADS)

    Daly, John; Liu, Jianbo; Aghagolzadeh, Mehdi; Oweiss, Karim

    2012-12-01

    Brain-machine interfaces (BMIs) aim to restore lost sensorimotor and cognitive function in subjects with severe neurological deficits. In particular, lost somatosensory function may be restored by artificially evoking patterns of neural activity through microstimulation to induce perception of tactile and proprioceptive feedback to the brain about the state of the limb. Despite an early proof of concept that subjects could learn to discriminate a limited vocabulary of intracortical microstimulation (ICMS) patterns that instruct the subject about the state of the limb, the dynamics of a moving limb are unlikely to be perceived by an arbitrarily-selected, discrete set of static microstimulation patterns, raising questions about the generalization and the scalability of this approach. In this work, we propose a microstimulation protocol intended to activate optimally the ascending somatosensory pathway. The optimization is achieved through a space-time precoder that maximizes the mutual information between the sensory feedback indicating the limb state and the cortical neural response evoked by thalamic microstimulation. Using a simplified multi-input multi-output model of the thalamocortical pathway, we show that this optimal precoder can deliver information more efficiently in the presence of noise compared to suboptimal precoders that do not account for the afferent pathway structure and/or cortical states. These results are expected to enhance the way microstimulation is used to induce somatosensory perception during sensorimotor control of artificial devices or paralyzed limbs.

  1. Scientific Inquiry in Educational Multi-User Virtual Environments

    ERIC Educational Resources Information Center

    Nelson, Brian C.; Ketelhut, Diane Jass

    2007-01-01

    In this paper, we present a review of research into the problems of implementing authentic scientific inquiry curricula in schools and the emerging use of educational Multi-User Virtual Environments (MUVEs) to support interactive scientific inquiry practices. Our analysis of existing literature in this growing area of study reveals three recurrent…

  2. Multi-User Droplet Combustion Apparatus - Flame Extinguishment Experiment

    NASA Technical Reports Server (NTRS)

    Williams, Forman A.; Nayagam, Vedha; Choi, Mun Y.; Dryer, Frederick L.; Shaw, Benjamin D.

    2009-01-01

    Multi-User Droplet Combustion Apparatus Flame Extinguishment Experiment (MDCA-FLEX) will assess the effectiveness of fire suppressants in microgravity and quantify the effect of different possible crew exploration atmospheres on fire suppression. The goal of this research is to provide definition and direction for large scale fire suppression tests and selection of the fire suppressant for next generation crew exploration vehicles.

  3. A Multi-User Remote Academic Laboratory System

    ERIC Educational Resources Information Center

    Barrios, Arquimedes; Panche, Stifen; Duque, Mauricio; Grisales, Victor H.; Prieto, Flavio; Villa, Jose L.; Chevrel, Philippe; Canu, Michael

    2013-01-01

    This article describes the development, implementation and preliminary operation assessment of Multiuser Network Architecture to integrate a number of Remote Academic Laboratories for educational purposes on automatic control. Through the Internet, real processes or physical experiments conducted at the control engineering laboratories of four…

  4. MATCON MODIFIED ASPHALT CONTAINMENT SYSTEM FOR MULTI-USE BROWNFIELDS

    EPA Science Inventory

    The concept of putting brownfield real estate back into safe and practical use is very appealing o both the owner and the neighborhood. Environmental regulations often preclude multi-use alterantives because traditional containment solutions rely on water barrier covers. These ar...

  5. Introducing ORACLE: Library Processing in a Multi-User Environment.

    ERIC Educational Resources Information Center

    Queensland Library Board, Brisbane (Australia).

    Currently being developed by the State Library of Queensland, Australia, ORACLE (On-Line Retrieval of Acquisitions, Cataloguing, and Circulation Details for Library Enquiries) is a computerized library system designed to provide rapid processing of library materials in a multi-user environment. It is based on the Australian MARC format and fully…

  6. Multi-User Hardware Solutions to Combustion Science ISS Research

    NASA Technical Reports Server (NTRS)

    Otero, Angel M.

    2001-01-01

    In response to the budget environment and to expand on the International Space Station (ISS) Fluids and Combustion Facility (FCF) Combustion Integrated Rack (CIR), common hardware approach, the NASA Combustion Science Program shifted focus in 1999 from single investigator PI (Principal Investigator)-specific hardware to multi-user 'Minifacilities'. These mini-facilities would take the CIR common hardware philosophy to the next level. The approach that was developed re-arranged all the investigations in the program into sub-fields of research. Then common requirements within these subfields were used to develop a common system that would then be complemented by a few PI-specific components. The sub-fields of research selected were droplet combustion, solids and fire safety, and gaseous fuels. From these research areas three mini-facilities have sprung: the Multi-user Droplet Combustion Apparatus (MDCA) for droplet research, Flow Enclosure for Novel Investigations in Combustion of Solids (FEANICS) for solids and fire safety, and the Multi-user Gaseous Fuels Apparatus (MGFA) for gaseous fuels. These mini-facilities will develop common Chamber Insert Assemblies (CIA) and diagnostics for the respective investigators complementing the capability provided by CIR. Presently there are four investigators for MDCA, six for FEANICS, and four for MGFA. The goal of these multi-user facilities is to drive the cost per PI down after the initial development investment is made. Each of these mini-facilities will become a fixture of future Combustion Science NASA Research Announcements (NRAs), enabling investigators to propose against an existing capability. Additionally, an investigation is provided the opportunity to enhance the existing capability to bridge the gap between the capability and their specific science requirements. This multi-user development approach will enable the Combustion Science Program to drive cost per investigation down while drastically reducing the time

  7. Potential of dynamic spectrum allocation in LTE macro networks

    NASA Astrophysics Data System (ADS)

    Hoffmann, H.; Ramachandra, P.; Kovács, I. Z.; Jorguseski, L.; Gunnarsson, F.; Kürner, T.

    2015-11-01

    In recent years Mobile Network Operators (MNOs) worldwide are extensively deploying LTE networks in different spectrum bands and utilising different bandwidth configurations. Initially, the deployment is coverage oriented with macro cells using the lower LTE spectrum bands. As the offered traffic (i.e. the requested traffic from the users) increases the LTE deployment evolves with macro cells expanded with additional capacity boosting LTE carriers in higher frequency bands complemented with micro or small cells in traffic hotspot areas. For MNOs it is crucial to use the LTE spectrum assets, as well as the installed network infrastructure, in the most cost efficient way. The dynamic spectrum allocation (DSA) aims at (de)activating the available LTE frequency carriers according to the temporal and spatial traffic variations in order to increase the overall LTE system performance in terms of total network capacity by reducing the interference. This paper evaluates the DSA potential of achieving the envisaged performance improvement and identifying in which system and traffic conditions the DSA should be deployed. A self-optimised network (SON) DSA algorithm is also proposed and evaluated. The evaluations have been carried out in a hexagonal and a realistic site-specific urban macro layout assuming a central traffic hotspot area surrounded with an area of lower traffic with a total size of approximately 8 × 8 km2. The results show that up to 47 % and up to 40 % possible DSA gains are achievable with regards to the carried system load (i.e. used resources) for homogenous traffic distribution with hexagonal layout and for realistic site-specific urban macro layout, respectively. The SON DSA algorithm evaluation in a realistic site-specific urban macro cell deployment scenario including realistic non-uniform spatial traffic distribution shows insignificant cell throughput (i.e. served traffic) performance gains. Nevertheless, in the SON DSA investigations, a gain of up

  8. Non-LTE effects in Al I lines

    NASA Astrophysics Data System (ADS)

    Menzhevitski, V. S.; Shimansky, V. V.; Shimanskaya, N. N.

    2012-07-01

    We present the theoretical analysis of the Al I line formation in the spectra of late-type stars ignoring the assumption of local thermodynamic equilibrium (LTE). The calculations were based on the 39-level aluminum atom model for one-dimensional hydrostatic stellar atmosphere models with the parameters: T eff from 4000 to 9000 K, log g = 0.0-4.5, and metallicity [ A] = 0.0;-1.0;-2.0;-3.0;-4.0. The aluminum atom model and the method of calculations were tested by the study of line profiles in the solar spectrum. We refined the oscillator strengths and Van-der-Vaals broadening constants C 6 of the investigated transitions. We conclude that the Al I atom is in the overionization state: the 3 p level is underpopulated in the line formation region. This leads to the line weakening, as compared with the LTE results. The overionization effect becomes more pronounced with increasing temperature and decreasing metallicity. We show that the use of various atomic data (ionization cross-sections) for the low levels of Al I does not change the behavior of non-LTE deviations, whereas the value of these deviations varies essentially. For nine selected Al I lines we calculated the grids of theoretical non-LTE corrections (Δ X NLTE = log ɛ NLTE - log ɛ LTE) to the Al abundances determinedwith the LTE assumption. The non-LTE corrections are positive and significant for the stars with temperatures T eff > 6000 K. These corrections weakly depend on log g, and increase with declining stellar metallicity.

  9. Performance analysis of precoding-based asymmetrically clipped optical orthogonal frequency division multiplexing wireless system in additive white Gaussian noise and indoor multipath channel

    NASA Astrophysics Data System (ADS)

    Ranjha, Bilal; Zhou, Zhou; Kavehrad, Mohsen

    2014-08-01

    We have compared the bit error rate (BER) performance of precoding-based asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) and pulse amplitude modulated discrete multitone (PAM-DMT) optical wireless (OW) systems in additive white Gaussian noise (AWGN) and indoor multipath frequency selective channel. Simulation and analytical results show that precoding schemes such as discrete Fourier transform, discrete cosine transform, and Zadoff-Chu sequences do not affect the performance of the OW systems in the AWGN channel while they do reduce the peak-to-average power ratio (PAPR) of the OFDM output signal. However, in a multipath indoor channel, using zero forcing frequency domain equalization precoding-based systems give better BER performance than their conventional counterparts. With additional clipping to further reduce the PAPR, precoding-based systems also show better BER performance compared to nonprecoded systems when clipped relative to the peak of nonprecoded systems. Therefore, precoding-based ACO-OFDM and PAM-DMT systems offer better BER performance, zero signaling overhead, and low PAPR compared to conventional systems.

  10. Pricing Resources in LTE Networks through Multiobjective Optimization

    PubMed Central

    Lai, Yung-Liang; Jiang, Jehn-Ruey

    2014-01-01

    The LTE technology offers versatile mobile services that use different numbers of resources. This enables operators to provide subscribers or users with differential quality of service (QoS) to boost their satisfaction. On one hand, LTE operators need to price the resources high for maximizing their profits. On the other hand, pricing also needs to consider user satisfaction with allocated resources and prices to avoid “user churn,” which means subscribers will unsubscribe services due to dissatisfaction with allocated resources or prices. In this paper, we study the pricing resources with profits and satisfaction optimization (PRPSO) problem in the LTE networks, considering the operator profit and subscribers' satisfaction at the same time. The problem is modelled as nonlinear multiobjective optimization with two optimal objectives: (1) maximizing operator profit and (2) maximizing user satisfaction. We propose to solve the problem based on the framework of the NSGA-II. Simulations are conducted for evaluating the proposed solution. PMID:24526889

  11. Adaptive Modulation and Coding for LTE Wireless Communication

    NASA Astrophysics Data System (ADS)

    Hadi, S. S.; Tiong, T. C.

    2015-04-01

    Long Term Evolution (LTE) is the new upgrade path for carrier with both GSM/UMTS networks and CDMA2000 networks. The LTE is targeting to become the first global mobile phone standard regardless of the different LTE frequencies and bands use in other countries barrier. Adaptive Modulation and Coding (AMC) is used to increase the network capacity or downlink data rates. Various modulation types are discussed such as Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (QAM). Spatial multiplexing techniques for 4×4 MIMO antenna configuration is studied. With channel station information feedback from the mobile receiver to the base station transmitter, adaptive modulation and coding can be applied to adapt to the mobile wireless channels condition to increase spectral efficiencies without increasing bit error rate in noisy channels. In High-Speed Downlink Packet Access (HSDPA) in Universal Mobile Telecommunications System (UMTS), AMC can be used to choose modulation types and forward error correction (FEC) coding rate.

  12. Pricing resources in LTE networks through multiobjective optimization.

    PubMed

    Lai, Yung-Liang; Jiang, Jehn-Ruey

    2014-01-01

    The LTE technology offers versatile mobile services that use different numbers of resources. This enables operators to provide subscribers or users with differential quality of service (QoS) to boost their satisfaction. On one hand, LTE operators need to price the resources high for maximizing their profits. On the other hand, pricing also needs to consider user satisfaction with allocated resources and prices to avoid "user churn," which means subscribers will unsubscribe services due to dissatisfaction with allocated resources or prices. In this paper, we study the pricing resources with profits and satisfaction optimization (PRPSO) problem in the LTE networks, considering the operator profit and subscribers' satisfaction at the same time. The problem is modelled as nonlinear multiobjective optimization with two optimal objectives: (1) maximizing operator profit and (2) maximizing user satisfaction. We propose to solve the problem based on the framework of the NSGA-II. Simulations are conducted for evaluating the proposed solution. PMID:24526889

  13. Non-LTE model atmospheres for hot evolved stars.

    NASA Astrophysics Data System (ADS)

    Werner, K.; Dreizler, S.; Heber, U.; Hunger, K.; Rauch, T.

    During the last years the authors have developed a computer code to construct non-LTE model atmospheres for hot stars including line blanketing effects. The particular methods gave way to the computation of non-LTE model atmospheres which account for many more opacity sources than could be treated within the classical complete linearisation approach by Auer and Mihalas. With this code it became possible for the first time to calculate grids of realistic non-LTE line blanketed model atmospheres for subdwarf O-stars in a critical temperature range as well as for the extremely hot (100,000K to 150,000K) so-called PG1159 stars. Both groups of stars consist of objects being in advanced evolutionary stages representing immediate White Dwarf progenitors. The atmospheres of these stars are enriched or even dominated by nuclear processed material, namely either by helium (sdO stars) or also by carbon and oxygen (PG1159 stars).

  14. Interfacing laboratory instruments to multiuser, virtual memory computers

    NASA Technical Reports Server (NTRS)

    Generazio, Edward R.; Stang, David B.; Roth, Don J.

    1989-01-01

    Incentives, problems and solutions associated with interfacing laboratory equipment with multiuser, virtual memory computers are presented. The major difficulty concerns how to utilize these computers effectively in a medium sized research group. This entails optimization of hardware interconnections and software to facilitate multiple instrument control, data acquisition and processing. The architecture of the system that was devised, and associated programming and subroutines are described. An example program involving computer controlled hardware for ultrasonic scan imaging is provided to illustrate the operational features.

  15. Interfacing laboratory instruments to multiuser, virtual memory computers

    NASA Technical Reports Server (NTRS)

    Generazio, Edward R.; Roth, Don J.; Stang, David B.

    1990-01-01

    Incentives, problems and solutions associated with interfacing laboratory equipment with multiuser, virtual memory computers are presented. The major difficulty concerns how to utilize these computers effectively in a medium sized research group. This entails optimization of hardware interconnections and software to facilitate multiple instrument control, data acquisition and processing. The architecture of the system that was devised, and associated programming and subroutines are described. An example program involving computer controlled hardware for ultrasonic scan imaging is provided to illustrate the operational features.

  16. Demonstration of high-speed quadrature phase shift keying vector signal generation employing a single Mach-Zehnder modulator with phase precoding technology

    NASA Astrophysics Data System (ADS)

    Wang, Yanyi; Li, Xinying; Yu, Jianjun

    2016-01-01

    We numerically and experimentally investigate high-speed quadrature phase shift keying (QPSK) vector signal generation based on a single Mach-Zehnder intensity modulator employing a precoding technique. We experimentally demonstrate 16-Gbaud QPSK vector signal generation at 16-GHz carrier adopting optical carrier suppression with precoding technique, and it is the highest baud rate generated by this technology. The 16-Gbaud QPSK modulated vector signal is delivered over a 20-km large effective area fiber or 2-km single-mode fiber with a bit-error-rate less than the hard-decision forward-error-correction threshold of 3.8×10-3.

  17. Revisiting HD 189733b's non-LTE Emission

    NASA Astrophysics Data System (ADS)

    Zellem, Robert T.; Swain, Mark R.; Drossart, Pierre; Iyer, Aishwarya

    2016-01-01

    The reported detection of non-LTE emission from the transiting hot Jupiter HD 189733b has proved both intriguing and controversial with published results both confirming and contradicting the original findings. We present new high-resolution L-band spectroscopy of HD 189733b's secondary eclipse and interpret these new findings in the context of the pervious work.

  18. TD-LTE maritime trunking communication system based on TVWS

    NASA Astrophysics Data System (ADS)

    Ren, Chunxiang; Chen, Xing; Li, Wanchao; Chen, Baodan

    2014-10-01

    This paper collects the measurement results of 470 MHZ-960MHZ spectrum in the coastal areas, and analyzes the characteristics of TV broadcast spectrum occupancy in the measurement region. Moreover, this article proposes construct the TD-LTE maritime trunking communication system using geolocation database, television database (TVDB) and cognitive radio (CR) technology.

  19. Supporting Dynamic Spectrum Access in Heterogeneous LTE+ Networks

    SciTech Connect

    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.

  20. Uplink Scheduling and Adjacent-Channel Coupling Loss Analysis for TD-LTE Deployment

    PubMed Central

    Yeo, Woon-Young; Moon, Sung Ho

    2014-01-01

    TD-LTE, one of the two duplexing modes in LTE, operates in unpaired spectrum and has the advantages of TDD-based technologies. It is expected that TD-LTE will be more rapidly deployed in near future and most of WiMax operators will upgrade their networks to TD-LTE gradually. Before completely upgrading to TD-LTE, WiMax may coexist with TD-LTE in an adjacent frequency band. In addition, multiple TD-LTE operators may deploy their networks in adjacent bands. When more than one TDD network operates in adjacent frequency bands, severe interference may happen due to adjacent channel interference (ACI) and unsynchronized operations. In this paper, coexistence issues between TD-LTE and other systems are analyzed and coexistence requirements are provided. This paper has three research objectives. First, frame synchronization between TD-LTE and WiMax is discussed by investigating possible combinations of TD-LTE and WiMax configurations. Second, an uplink scheduling algorithm is proposed to utilize a leakage pattern of ACI in synchronized operations. Third, minimum requirements for coexistence in unsynchronized operations are analyzed by introducing a concept of adjacent-channel coupling loss. From the analysis and simulation results, we can see that coexistence of TD-LTE with other TDD systems is feasible if the two networks are synchronized. For the unsynchronized case, some special cell-site engineering techniques may be required to reduce the ACI. PMID:24707214

  1. Uplink scheduling and adjacent-channel coupling loss analysis for TD-LTE deployment.

    PubMed

    Yeo, Woon-Young; Moon, Sung Ho; Kim, Jae-Hoon

    2014-01-01

    TD-LTE, one of the two duplexing modes in LTE, operates in unpaired spectrum and has the advantages of TDD-based technologies. It is expected that TD-LTE will be more rapidly deployed in near future and most of WiMax operators will upgrade their networks to TD-LTE gradually. Before completely upgrading to TD-LTE, WiMax may coexist with TD-LTE in an adjacent frequency band. In addition, multiple TD-LTE operators may deploy their networks in adjacent bands. When more than one TDD network operates in adjacent frequency bands, severe interference may happen due to adjacent channel interference (ACI) and unsynchronized operations. In this paper, coexistence issues between TD-LTE and other systems are analyzed and coexistence requirements are provided. This paper has three research objectives. First, frame synchronization between TD-LTE and WiMax is discussed by investigating possible combinations of TD-LTE and WiMax configurations. Second, an uplink scheduling algorithm is proposed to utilize a leakage pattern of ACI in synchronized operations. Third, minimum requirements for coexistence in unsynchronized operations are analyzed by introducing a concept of adjacent-channel coupling loss. From the analysis and simulation results, we can see that coexistence of TD-LTE with other TDD systems is feasible if the two networks are synchronized. For the unsynchronized case, some special cell-site engineering techniques may be required to reduce the ACI. PMID:24707214

  2. Photonic-aided pre-coding QAM signal transmission in multi-antenna radio over fiber system

    NASA Astrophysics Data System (ADS)

    Zhang, Qi; Yu, Jianjun; Li, Xinying; Zhu, Ming; Xin, Xiangjun; Chang, Gee-Kung

    2015-11-01

    A novel method has been proposed and experimentally demonstrated to provide photonic-aided pre-coding quadrature amplitude modulation (QAM) signal transmission in multi-antenna radio over fiber system to increase the throughput. For downlink, two different multi-level amplitude-shift-keying (M-ASK) modulated signals, such as 4-ASK signals, are applied on two uncorrelated optical Mach-Zehnder modulators at central office. After photonic-aided pre-coding module and photo-detection process, the received M-ASK mm-waves from two remote access units (RAUs) can be synthesized to a M2-QAM signal in the proposed system. Regardless of forward error correction (FEC) coding overhead, the 4-Gb/s and 8-Gb/s 16-QAM mm-wave signals are obtained from two independent 2-Gb/s and 4-Gb/s 4-ASK 40-GHz channels, respectively. The experimental results show that a doubled bit rate of the original 4-ASK one can be achieved without additional digital signal processing (DSP) in small cell RAUs and mobile users.

  3. An Adjustable Scheduling Algorithm for Multi-User MIMO Systems

    NASA Astrophysics Data System (ADS)

    Kim, Jaehong; Lee, Sangjae; Kim, Sehun

    Multiple Input Multiple Output (MIMO) represents a highly promising technique for 4G communication networks as it uses multiple antennas at the transmitter and receiver to improve the reliability of transmissions and to provide a high data rate. This paper introduces an adjustable scheduling algorithm for multi-user MIMO systems that can provide an advantageous trade-off solution between throughput maximization and fair resource allocation among users. Specifically, our algorithm is proposed as a solution to system requirement issues through the flexible control of fairness factors.

  4. Managing a Safe and Successful Multi-User Spaceport

    NASA Technical Reports Server (NTRS)

    Dacko, Taylor; Ketterer, Kirk; Meade, Phillip

    2016-01-01

    Encouraged by the creation of the Office of Commercial Space Transportation within the U.S. Federal Aviation Administration (FAA) in 1984 and the Commercial Space Act of 1998, the National Aeronautics and Space Administration (NASA) now relies on an extensive network of support from commercial companies and organizations. At NASA's Kennedy Space Center (KSC), this collaboration opens competitive opportunities for launch providers, including repurposing underutilized Shuttle Program resources, constructing new facilities, and utilizing center services and laboratories. The resulting multi-user spaceport fosters diverse activity, though it engenders risk from hazards associated with various spaceflight processing activities. The KSC Safety & Mission Assurance (S&MA) Directorate, in coordination with the center's Spaceport Integration and Center Planning & Development organizations, has developed a novel approach to protect NASA's workforce, critical assets, and the public from hazardous, space-related activity associated with KSC's multi-user spaceport. For NASA KSC S&MA, the transformation to a multi-user spaceport required implementing methods to foster safe and successful commercial activity while resolving challenges involving: Retirement of the Space Shuttle program; Co-location of multiple NASA programs; Relationships between the NASA programs; Complex relationships between NASA programs and commercial partner operations in exclusive-use facilities; Complex relationships between NASA programs and commercial partner operations in shared-use facilities. NASA KSC S&MA challenges were met with long-term planning and solutions involving cooperation with the Spaceport Integration and Services Directorate. This directorate is responsible for managing active commercial partnerships with customer advocacy and services management, providing a dedicated and consistent level of support to a wide array of commercial operations. This paper explores these solutions, their

  5. Performance of Multi-User Transmitter Pre-Processing Assisted Multi-Cell IDMA System for Downlink Transmission

    NASA Astrophysics Data System (ADS)

    Partibane, B.; Nagarajan, V.; Vishvaksenan, K. S.; Kalidoss, R.

    2015-06-01

    In this paper, we present the performance of multi-user transmitter pre-processing (MUTP) assisted coded-interleave division multiple access (IDMA) system over correlated frequency-selective channels for downlink communication. We realize MUTP using singular value decomposition (SVD) technique, which exploits the channel state information (CSI) of all the active users that is acquired via feedback channels. We consider the MUTP technique to alleviate the effects of co-channel interference (CCI) and multiple access interference (MAI). To be specific, we estimate the CSI using least square error (LSE) algorithm at each of the mobile stations (MSs) and perform vector quantization using Lloyd's algorithm, and feedback the bits that represents the quantized magnitudes and phases to the base station (BS) through the dedicated low rate noisy channel. Finally we recover the quantized bits at the BS to formulate the pre-processing matrix. The performance of MUTP aided IDMA systems are evaluated for five types of delay spread distributions pertaining to long-term evolution (LTE) and Stanford University Interim (SUI) channel models. We also compare the performance of MUTP with minimum mean square error (MMSE) detector for the coded IDMA system. The considered TP scheme alleviates the effects of CCI with less complex signal detection at the MSs when compared to MMSE detector. Further, our simulation results reveal that SVD-based MUTP assisted coded IDMA system outperforms the MMSE detector in terms of achievable bit error rate (BER) with low signal-to-noise ratio (SNR) requirement by mitigating the effects of CCI and MAI.

  6. Multiuser sonar watermarking and detection in an underwater acoustic channel

    NASA Astrophysics Data System (ADS)

    Mobasseri, Bijan G.; Lynch, Robert S.; Andiario, David

    2013-06-01

    Sonar watermarking is the practice of embedding low-power, secure digital signatures in the time frequency space of a waveform. The algorithm is designed for a single source/receiver configuration. However, in a multiuser environment, multiple sources broadcast sonar waveforms that overlap in both time and frequency. The receiver can be configured as a filter bank where each bank is dedicated to detecting a specific watermark. However, a filter bank is prone to mutual interference as multiple sonar waveforms are simultaneously present at the detector input. To mitigate mutual interference, a multiuser watermark detector is formulated as a decorrelating detector that decouples detection amongst the watermark signatures. The acoustic channel is simulated in software and modeled by an FIR filter. This model is used to compensate for the degradation of spreading sequences used for watermark embedding. The test statistic generated at the output of the decorrelating detector is used in a joint maximum likelihood ratio detector to establish the presence or absence of the watermark in each sonar waveform. ROC curves are produced for multiple sources positioned at varying ranges subject to ambient ocean noise controlled by varying sea states.

  7. Non-LTE Modeling of the Stratosphere of Jupiter

    NASA Astrophysics Data System (ADS)

    Zhang, X.; West, R. A.; Shia, R.; Yelle, R. V.; Yung, Y. L.

    2011-12-01

    Thermal infrared emission from Jovian atmosphere itself is absorbed and re-emitted and causes the atmospheric cooling to space. Above about 1 mbar, Non-Local Thermodynamic Equilibrium (Non-LTE) effect may be important for the IR cooling rate and therefore the atmospheric heat balance. In this study, a Non-LTE radiative transfer model is introduced to calculate the cooling rate via the IR bands of the hydrocarbon species including CH4 at 7.7 μm, C2H6 at 12.2 μm, and C2H2 at 14 μm. Collisional de-activation (quenching) rates of the excited states of these hydrocarbon species in a hydrogen-rich atmosphere are the major unknown parameters in the current literature. However, our results show that, the radiative budget of the upper stratosphere of Jupiter depends crucially on the quenching rates. The effect on the stratospheric circulation and hydrocarbon distribution is discussed.

  8. Design and optimization of LTE 1800 MIMO antenna.

    PubMed

    Wong, Huey Shin; Islam, Mohammad Tariqul; Kibria, Salehin

    2014-01-01

    A multiple input and multiple output (MIMO) antenna that comprises a printed microstrip antenna and a printed double-L sleeve monopole antenna for LTE 1800 wireless application is presented. The printed double-L sleeve monopole antenna is fed by a 50 ohm coplanar waveguide (CPW). A novel T-shaped microstrip feedline printed on the other side of the PCB is used to excite the waveguide's outer shell. Isolation characteristics better than -15 dB can be obtained for the proposed MIMO antenna. The proposed antenna can operate in LTE 1800 (1710 MHz-1880 MHz). This antenna exhibits omnidirectional characteristics. The efficiency of the antenna is greater than 70% and has high gain of 2.18 dBi. PMID:24967440

  9. Design and Optimization of LTE 1800 MIMO Antenna

    PubMed Central

    Wong, Huey Shin; Islam, Mohammad Tariqul

    2014-01-01

    A multiple input and multiple output (MIMO) antenna that comprises a printed microstrip antenna and a printed double-L sleeve monopole antenna for LTE 1800 wireless application is presented. The printed double-L sleeve monopole antenna is fed by a 50 ohm coplanar waveguide (CPW). A novel T-shaped microstrip feedline printed on the other side of the PCB is used to excite the waveguide's outer shell. Isolation characteristics better than −15 dB can be obtained for the proposed MIMO antenna. The proposed antenna can operate in LTE 1800 (1710 MHz–1880 MHz). This antenna exhibits omnidirectional characteristics. The efficiency of the antenna is greater than 70% and has high gain of 2.18 dBi. PMID:24967440

  10. Non-LTE Line Formation for Hydrogen Revisited

    NASA Astrophysics Data System (ADS)

    Przybilla, Norbert; Butler, Keith

    2004-07-01

    We discuss aspects of non-LTE line formation for hydrogen in early-type stars. We evaluate the effect of variations in the electron-impact excitation cross sections in model atoms of differing complexity by comparison with observation. While the Balmer lines are basically unaffected by the choice of atomic data, the Paschen, Brackett, and Pfund series members allow us to discriminate between the different models. Non-LTE calculations based on the widely used approximation formulae of Mihalas, Heasley, & Auer and of Johnson fail to simultaneously reproduce the optical and IR spectra over the entire parameter range. The use of data from ab initio calculations up to principal quantum number n<=7 largely solves the problem. We recommend a reference model using the available data. This model is of general interest because of the ubiquity of the hydrogen spectrum.

  11. Reproducible LTE uplink performance analysis using precomputed interference signals

    NASA Astrophysics Data System (ADS)

    Pauli, Volker; Nisar, Muhammad Danish; Seidel, Eiko

    2011-12-01

    The consideration of realistic uplink inter-cell interference is essential for the overall performance testing of future cellular systems, and in particular for the evaluation of the radio resource management (RRM) algorithms. Most beyond-3G communication systems employ orthogonal multiple access in uplink (SC-FDMA in LTE and OFDMA in WiMAX), and additionally rely on frequency-selective RRM (scheduling) algorithms. This makes the task of accurate modeling of uplink interference both crucial and non-trivial. Traditional methods for its modeling (e.g., via additive white Gaussian noise interference sources) are therefore proving to be ineffective to realistically model the uplink interference in the next generation cellular systems. In this article, we propose the use of realistic precomputed interference patterns for LTE uplink performance analysis and testing. The interference patterns are generated via an LTE system-level simulator for a given set of scenario parameters, such as cell configuration, user configurations, and traffic models. The generated interference patterns (some of which are made publicly available) can be employed to benchmark the performance of any LTE uplink system in both lab simulations and field trials for practical deployments. It is worth mentioning that the proposed approach can also be extended to other cellular communication systems employing OFDMA-like multiple access with frequency-selective RRM techniques. The proposed approach offers twofold advantages. First, it allows for repeatability and reproducibility of the performance analysis. This is of crucial significance not only for researchers and developers to analyze the behavior and performance of their systems, but also for the network operators to compare the performance of competing system vendors. Second, the proposed testing mechanism evades the need for deployment of multiple cells (with multiple active users in each) to achieve realistic field trials, thereby resulting in

  12. Traffic Dimensioning and Performance Modeling of 4G LTE Networks

    ERIC Educational Resources Information Center

    Ouyang, Ye

    2011-01-01

    Rapid changes in mobile techniques have always been evolutionary, and the deployment of 4G Long Term Evolution (LTE) networks will be the same. It will be another transition from Third Generation (3G) to Fourth Generation (4G) over a period of several years, as is the case still with the transition from Second Generation (2G) to 3G. As a result,…

  13. Cost-Effectiveness of Home Energy Retrofits in Pre-Code Vintage Homes in the United States

    SciTech Connect

    Fairey, P.; Parker, D.

    2012-11-01

    This analytical study examines the opportunities for cost-effective energy efficiency and renewable energy retrofits in residential archetypes constructed prior to 1980 (Pre-Code) in fourteen U.S. cities. These fourteen cities are representative of each of the International Energy Conservation Code (IECC) climate zones in the contiguous U.S. The analysis is conducted using an in-house version of EnergyGauge USA v.2.8.05 named CostOpt that has been programmed to perform iterative, incremental economic optimization on a large list of residential energy efficiency and renewable energy retrofit measures. The principle objectives of the study are as follows: to determine the opportunities for cost effective source energy reductions in this large cohort of existing residential building stock as a function of local climate and energy costs; and to examine how retrofit financing alternatives impact the source energy reductions that are cost effectively achievable.

  14. Non-LTE analysis of Uranus Observations from Spitzer

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Martin-Torres, F.; Yung, Y. L.; Orton, G. S.; Fletcher, L. N.

    2009-12-01

    Spitzer Infrared Spectrometer (IRS) observations of the disk of Uranus between 5.2 and 32 microns (1920 cm-1-270 cm-1) contain a wealth of information about the its cold atmosphere. In particular, they enable the retrieval of temperature and the abundances of several gaseous species as a function of pressure. They can also be used to study the energetics of radiatively active species in regions of Uranus’ atmosphere where Local Thermodynamic Equilibrium (LTE) is expected to break down. Care must be taken in atmospheric sounding not to assume that the atmospheric compounds emit according to the Planck function at the local kinetic temperature. Many of the ro-vibrational states of atmospheric constituents responsible for infrared emissions have excitation temperatures that differ from the local kinetic temperature. While non-LTE emission has been extensively considered for remote sensing of the Earth, only one study by Appleby (Icarus, 85, p355-379, 1990), who examined the radiative equilibrium temperatures of methane (CH4) in the upper atmospheres of Jupiter, Saturn, Uranus, and Neptune, has estimated the influence of non-LTE effects in Uranus' upper atmosphere. Uranus is composed mainly of hydrogen and helium. Helium is radiatively inactive, and hydrogen is active only in its weak collision-induced absorption, and its quadrupole lines. At low pressures, non-LTE processes involve the quantum levels of the more abundant minor constituents become important. In the case of Uranus the most important gas in the latter category is CH4, which has a role rather analogous to that of carbon dioxide in the Earth’s atmosphere. Since the work by Appleby, the spectroscopic and kinetics information of methane and other hydrocarbons has greatly improved and computer capabilities allow avoiding previous simplifications. For example, the full coupling between CH4 v4 and the higher-energy vibrational states emitting/absorbing in the near-IR is now possible. In this presentation we

  15. Collisional-radiative switching - A powerful technique for converging non-LTE calculations

    NASA Technical Reports Server (NTRS)

    Hummer, D. G.; Voels, S. A.

    1988-01-01

    A very simple technique has been developed to converge statistical equilibrium and model atmospheric calculations in extreme non-LTE conditions when the usual iterative methods fail to converge from an LTE starting model. The proposed technique is based on a smooth transition from a collision-dominated LTE situation to the desired non-LTE conditions in which radiation dominates, at least in the most important transitions. The proposed approach was used to successfully compute stellar models with He abundances of 0.20, 0.30, and 0.50; Teff = 30,000 K, and log g = 2.9.

  16. Center Planning and Development: Multi-User Spaceport Initiatives

    NASA Technical Reports Server (NTRS)

    Kennedy, Christopher John

    2015-01-01

    The Vehicle Assembly building at NASAs Kennedy Space Center has been used since 1966 to vertically assemble every launch vehicle, since the Apollo Program, launched from Launch Complex 39 (LC-39). After the cancellation of the Constellation Program in 2010 and the retirement of the Space Shuttle Program in 2011, the VAB faced an uncertain future. As the Space Launch System (SLS) gained a foothold as the future of American spaceflight to deep space, NASA was only using a portion of the VABs initial potential. With three high bays connected to the Crawler Way transportation system, the potential exists for up to three rockets to be simultaneously processed for launch. The Kennedy Space Center (KSC) Master plan, supported by the Center Planning and Development (CPD) Directorate, is guiding Kennedy toward a 21st century multi-user spaceport. This concept will maintain Kennedy as the United States premier gateway to space and provide multi-user operations through partnerships with the commercial aerospace industry. Commercial aerospace companies, now tasked with transporting cargo and, in the future, astronauts to the International Space Station (ISS) via the Commercial Resupply Service (CRS) and Commercial Crew Program (CCP), are a rapidly growing industry with increasing capabilities to make launch operations more economical for both private companies and the government. Commercial operations to Low Earth Orbit allow the government to focus on travel to farther destinations through the SLS Program. With LC-39B designated as a multi-use launch pad, companies seeking to use it will require an integration facility to assemble, integrate, and test their launch vehicle. An Announcement for Proposals (AFP) was released in June, beginning the process of finding a non-NASA user for High Bay 2 (HB2) and the Mobile Launcher Platforms (MLPs). An Industry Day, a business meeting and tour for interested companies and organizations, was also arranged to identify and answer any

  17. General-purpose interface bus for multiuser, multitasking computer system

    NASA Technical Reports Server (NTRS)

    Generazio, Edward R.; Roth, Don J.; Stang, David B.

    1990-01-01

    The architecture of a multiuser, multitasking, virtual-memory computer system intended for the use by a medium-size research group is described. There are three central processing units (CPU) in the configuration, each with 16 MB memory, and two 474 MB hard disks attached. CPU 1 is designed for data analysis and contains an array processor for fast-Fourier transformations. In addition, CPU 1 shares display images viewed with the image processor. CPU 2 is designed for image analysis and display. CPU 3 is designed for data acquisition and contains 8 GPIB channels and an analog-to-digital conversion input/output interface with 16 channels. Up to 9 users can access the third CPU simultaneously for data acquisition. Focus is placed on the optimization of hardware interfaces and software, facilitating instrument control, data acquisition, and processing.

  18. Authenticated multi-user quantum key distribution with single particles

    NASA Astrophysics Data System (ADS)

    Lin, Song; Wang, Hui; Guo, Gong-De; Ye, Guo-Hua; Du, Hong-Zhen; Liu, Xiao-Fen

    2016-03-01

    Quantum key distribution (QKD) has been growing rapidly in recent years and becomes one of the hottest issues in quantum information science. During the implementation of QKD on a network, identity authentication has been one main problem. In this paper, an efficient authenticated multi-user quantum key distribution (MQKD) protocol with single particles is proposed. In this protocol, any two users on a quantum network can perform mutual authentication and share a secure session key with the assistance of a semi-honest center. Meanwhile, the particles, which are used as quantum information carriers, are not required to be stored, therefore the proposed protocol is feasible with current technology. Finally, security analysis shows that this protocol is secure in theory.

  19. Design of stereoscopic display monitor for multi-users

    NASA Astrophysics Data System (ADS)

    Liu, Qing; Zhang, Yuncui; Liu, Long; Zou, Nianyu; Cao, Guanying; Dong, Xiaomei

    2011-12-01

    A new naked eyes stereoscopic display optical system for multi-users was proposed in this paper, different from the conventional naked eyes stereoscopic display monitors with sophistication technology and bad uniformity of illumination. According to the binocular parallax technology, Fresnel lens and polaroid sheet were chosen to focus the rays on the observers' eyes. Freeform lens were used in this system to enhance illumination uniformity of pictures and efficiency of the system. The results of simulation showed that the users can obtain stereoscopic effect at their each places, uniformity of illumination on LCD was above 0.6. Therefore, this system had a simple and compact structure, and the quality of pictures users obtain was better than system without freeform lenses.

  20. Multilevel and multi-user sustainability assessment of farming systems

    SciTech Connect

    Van Passel, Steven; Meul, Marijke

    2012-01-15

    Sustainability assessment is needed to build sustainable farming systems. A broad range of sustainability concepts, methodologies and applications already exists. They differ in level, focus, orientation, measurement, scale, presentation and intended end-users. In this paper we illustrate that a smart combination of existing methods with different levels of application can make sustainability assessment more profound, and that it can broaden the insights of different end-user groups. An overview of sustainability assessment tools on different levels and for different end-users shows the complementarities and the opportunities of using different methods. In a case-study, a combination of the sustainable value approach (SVA) and MOTIFS is used to perform a sustainability evaluation of farming systems in Flanders. SVA is used to evaluate sustainability at sector level, and is especially useful to support policy makers, while MOTIFS is used to support and guide farmers towards sustainability at farm level. The combined use of the two methods with complementary goals can widen the insights of both farmers and policy makers, without losing the particularities of the different approaches. To stimulate and support further research and applications, we propose guidelines for multilevel and multi-user sustainability assessments. - Highlights: Black-Right-Pointing-Pointer We give an overview of sustainability assessment tools for agricultural systems. Black-Right-Pointing-Pointer SVA and MOTIFS are used to evaluate the sustainability of dairy farming in Flanders. Black-Right-Pointing-Pointer Combination of methods with different levels broadens the insights of different end-user groups. Black-Right-Pointing-Pointer We propose guidelines for multilevel and multi-user sustainability assessments.

  1. Code-division multiple-access multiuser demodulator by using quantum fluctuations

    NASA Astrophysics Data System (ADS)

    Otsubo, Yosuke; Inoue, Jun-ichi; Nagata, Kenji; Okada, Masato

    2014-07-01

    We examine the average-case performance of a code-division multiple-access (CDMA) multiuser demodulator in which quantum fluctuations are utilized to demodulate the original message within the context of Bayesian inference. The quantum fluctuations are built into the system as a transverse field in the infinite-range Ising spin glass model. We evaluate the performance measurements by using statistical mechanics. We confirm that the CDMA multiuser modulator using quantum fluctuations achieve roughly the same performance as the conventional CDMA multiuser modulator through thermal fluctuations on average. We also find that the relationship between the quality of the original information retrieval and the amplitude of the transverse field is somehow a "universal feature" in typical probabilistic information processing, viz., in image restoration, error-correcting codes, and CDMA multiuser demodulation.

  2. Code-division multiple-access multiuser demodulator by using quantum fluctuations.

    PubMed

    Otsubo, Yosuke; Inoue, Jun-Ichi; Nagata, Kenji; Okada, Masato

    2014-07-01

    We examine the average-case performance of a code-division multiple-access (CDMA) multiuser demodulator in which quantum fluctuations are utilized to demodulate the original message within the context of Bayesian inference. The quantum fluctuations are built into the system as a transverse field in the infinite-range Ising spin glass model. We evaluate the performance measurements by using statistical mechanics. We confirm that the CDMA multiuser modulator using quantum fluctuations achieve roughly the same performance as the conventional CDMA multiuser modulator through thermal fluctuations on average. We also find that the relationship between the quality of the original information retrieval and the amplitude of the transverse field is somehow a "universal feature" in typical probabilistic information processing, viz., in image restoration, error-correcting codes, and CDMA multiuser demodulation. PMID:25122270

  3. Photonic frequency-quadrupling and balanced pre-coding technologies for W-band QPSK vector mm-wave signal generation based on a single DML

    NASA Astrophysics Data System (ADS)

    Wang, Yanyi; Yang, Chao; Chi, Nan; Yu, Jianjun

    2016-05-01

    We propose a novel scheme for high-frequency quadrature phase shift keying (QPSK) photonic vector signal generation based on a single directly modulated laser (DML) employing photonic frequency quadrupling and balanced pre-coding technologies. In order to realize frequency quadrupling, a wavelength selective switch (WSS) is intruded in our experiment. The intruded WSS combined with DML can not only realize high-frequency vector signal generation but also simplify the architecture. We experimentally demonstrate 1-or 2-Gbaud QPSK vector signal generation at 88 GHz based on our proposed scheme. The generated 1-Gbaud balanced pre-coded QPSK vector signal is transmitted 0.5-m wireless distance with the bit-error-ratio (BER) below hard-decision forward-error-correction (HD-FEC) threshold of 3.8×10-3. To our knowledge, this is the first time to demonstrate W-band mm-wave vector signal based on a single DML with quadrupling frequency and pre-coding technologies.

  4. Configuration interaction in LTE spectra of heavy elements

    SciTech Connect

    Bar-Shalom, A.; Oreg, J.; Goldstein, W.

    1992-11-01

    We present a method for including the effects of configuration interaction (CI) between relativistic subconfigurations of an electron configuration in the calculation of emission and absorption spectra of plasmas in local thermodynamic equilibrium (LTE). Analytical expressions for the correction to the intensities, owing to Cl, of an unresolved transition array (UTA) and of a supertransition array (STA) are obtained when the correction is small compared to the spin-orbit splitting, bypassing the need to diagonalize energy matrices. These expressions serve as working formulas in the STA model and, in addition, reveal a priori the conditions under which CI effects are significant. Examples of the effect are presented.

  5. LTE Model Atmospheres: MARCS, ATLAS and CO5BOLD

    NASA Astrophysics Data System (ADS)

    Bonifacio, P.; Caffau, E.; Ludwig, H.-G.; Steffen, M.

    2012-04-01

    In this talk, we review the basic assumptions and physics covered by classical 1D LTE model atmospheres. We will focus on ATLAS and MARCS models of F-G-K stars and describe what resources are available through the web, both in terms of codes and model-atmosphere grids. We describe the advances made in hydrodynamical simulations of convective stellar atmospheres with the CO5BOLD code and what grids and resources are available, with a prospect of what will be available in the near future.

  6. Accurate LTE abundances for some lambda Boo stars

    NASA Astrophysics Data System (ADS)

    Andrievsky, S. M.; Chernyshova, I. V.; Klochkova, V. G.; Panchuk, V. E.

    1998-04-01

    High-resolution and high S/N CCD spectra were analyzed to determine accurate LTE abundances in four lambda Boo stars: pi1 Ori, 29 Cyg, HR 8203 and 15 And. In general, 14 chemical elements were investigated. The main results are the following: all stars have a strong deficiency of the majority of investigated metals. Oxygen exhibits a moderate deficiency. The carbon abundance is close to the solar one. The results obtained support an accretion/diffusion model, which is currently adopted for the explanation of the lambda Boo phenomenon.

  7. Non-LTE oxygen line formation in 3D hydrodynamic model stellar atmospheres

    NASA Astrophysics Data System (ADS)

    Amarsi, A. M.; Asplund, M.; Collet, R.; Leenaarts, J.

    2016-02-01

    The O I 777 nm lines are among the most commonly used diagnostics for the oxygen abundances in the atmospheres of FGK-type stars. However, they form in conditions that are far from local thermodynamic equilibrium (LTE). We explore the departures from LTE of atomic oxygen, and their impact on O I lines, across the STAGGER-grid of three-dimensional hydrodynamic model atmospheres. For the O I 777 nm triplet, we find significant departures from LTE. These departures are larger in stars with larger effective temperatures, smaller surface gravities, and larger oxygen abundances. We present grids of predicted 3D non-LTE based equivalent widths for the O I 616 nm, [O I] 630 nm, [O I] 636 nm, and O I 777 nm lines, as well as abundance corrections to 1D LTE based results.

  8. Non-LTE modeling of cold stellar atmospheres

    NASA Astrophysics Data System (ADS)

    Feautrier, N.; Spielfiedel, A.; Guitou, M.; Belyaev, A. K.

    2014-12-01

    Non-LTE modelisation of stellar atmospheres requires an accurate knowledge of collisional rate coefficients (mainly with H atoms) that compete with radiative rates to populate the atomic levels. In the framework of the SAM-GAIA project we carry out an interdisciplinary work combining quantum chemistry and collision physics. Present studies concern collisional excitation of MgI, CaI and OI by H-atoms. Considering the Mg-H case, the resulting cross sections and rate coefficients point out the sensitivity of the results with the quantum chemistry data. The calculations show that the usual approximate Drawin formula leads to errors by factors up to 10^5. As was already found in Li+H and Na+H collisions, excitation processes were found of the same order of magnitude as charge transfer processes. However, unlike Li and Na, Mg has different spin terms, singlet and triplet, leading both to doublet molecular MgH electronic states. Collisional rates between spin-allowed and optically spin-forbidden atomic states are found to be of the same order of magnitude although optically spin-forbidden states are only collisionally coupled. Thus, we may expect consequences on non-LTE calculations.

  9. Constrained genetic algorithms for optimizing multi-use reservoir operation

    NASA Astrophysics Data System (ADS)

    Chang, Li-Chiu; Chang, Fi-John; Wang, Kuo-Wei; Dai, Shin-Yi

    2010-08-01

    To derive an optimal strategy for reservoir operations to assist the decision-making process, we propose a methodology that incorporates the constrained genetic algorithm (CGA) where the ecological base flow requirements are considered as constraints to water release of reservoir operation when optimizing the 10-day reservoir storage. Furthermore, a number of penalty functions designed for different types of constraints are integrated into reservoir operational objectives to form the fitness function. To validate the applicability of this proposed methodology for reservoir operations, the Shih-Men Reservoir and its downstream water demands are used as a case study. By implementing the proposed CGA in optimizing the operational performance of the Shih-Men Reservoir for the last 20 years, we find this method provides much better performance in terms of a small generalized shortage index (GSI) for human water demands and greater ecological base flows for most of the years than historical operations do. We demonstrate the CGA approach can significantly improve the efficiency and effectiveness of water supply capability to both human and ecological base flow requirements and thus optimize reservoir operations for multiple water users. The CGA can be a powerful tool in searching for the optimal strategy for multi-use reservoir operations in water resources management.

  10. [A multi-user documentation system for pain clinics.].

    PubMed

    Bautz, M; Pfingsten, M; Weber, M; Weyland, A; Ensink, B; Hildebrandt, J

    1989-09-01

    In pain clinics, thorough documentation of patient-related data is essential for analysis of patient history, long-term evaluation of diagnostic and therapeutic procedures, and research on the etiology and epidemiology of chronic pain syndromes. With these requirements in mind, we realized a microcomputer documentation system based on a commercial data-base software concept (dBASE). Each patient's data are stored in three different sections: data for identification, basic data (mainly diagnostic findings), and treatment related follow-up data. The program was initially developed to run on a single IBM/XT- or AT-compatible computer (at least 640 kB RAM, 1 hard-disk-drive) with MS-DOS but has now been improved to work on a local area network (LAN) with the NOVELL-Netware operating system. Important features of our new system are: multi-user capability, flexible data management via menu-driven user dialogue, rapid data access, and high compatibility allowing data exchange with other standard software packages. The microcomputer documentation system offers listings for administration as well as effective patient scheduling thanks to a recall system by date of last contact, selected therapeutic procedures and any other item in the medical record. A mail-merge service can be applied, which is particularly useful for follow-up-studies. The documentation system means routine work can be standardized and performed in an economical manner, with the ultimate aim of enhancing the quality of pain therapy. PMID:18415351

  11. The impact of multiuser virtual environments on student engagement.

    PubMed

    Claman, Faith L

    2015-01-01

    The purpose of this pilot study was to test the hypothesis that web-based synchronous instruction utilizing Multi-user Virtual World Environments (MUVEs) increases student engagement compared to traditional asynchronous learning methods. In a quasi-experimental two group posttest only study, a sample of Family Nurse Practitioner students (n = 21) received instruction using either a synchronous (n = 10) or asynchronous (n = 11) learning method. Engagement was measured using the Community of Inquiry survey. Results indicated that engagement scores were significantly higher for the synchronous learning platform (mean = 3.61, SD = 1.13) compared to the asynchronous learning platform (mean = 3.49, SD = 1.08, t(1766) = -2.21, p < 0.05). Increased student engagement with synchronous MUVE platforms have the potential to improve learning outcomes and offer nursing students a multitude of educational opportunities to practice new skills and behaviors in real life scenarios, all within the safety of a controlled environment. PMID:25532889

  12. Atmospheric lidar multi-user instrument system definition study

    NASA Technical Reports Server (NTRS)

    Greco, R. V. (Editor)

    1980-01-01

    A spaceborne lidar system for atmospheric studies was defined. The primary input was the Science Objectives Experiment Description and Evolutionary Flow Document. The first task of the study was to perform an experiment evolutionary analysis of the SEED. The second task was the system definition effort of the instrument system. The third task was the generation of a program plan for the hardware phase. The fourth task was the supporting studies which included a Shuttle deficiency analysis, a preliminary safety hazard analysis, the identification of long lead items, and development studies required. As a result of the study an evolutionary Lidar Multi-User Instrument System (MUIS) was defined. The MUIS occupies a full Spacelab pallet and has a weight of 1300 kg. The Lidar MUIS laser provides a 2 joule frequency doubled Nd:YAG laser that can also pump a tuneable dye laser wide frequency range and bandwidth. The MUIS includes a 1.25 meter diameter aperture Cassegrain receiver, with a moveable secondary mirror to provide precise alignment with the laser. The receiver can transmit the return signal to three single and multiple photomultiple tube detectors by use of a rotating fold mirror. It is concluded that the Lidar MUIS proceed to program implementation.

  13. Multi-user distribution of polarization entangled photon pairs

    NASA Astrophysics Data System (ADS)

    Trapateau, J.; Ghalbouni, J.; Orieux, A.; Diamanti, E.; Zaquine, I.

    2015-10-01

    We experimentally demonstrate multi-user distribution of polarization entanglement using commercial telecom wavelength division demultiplexers. The entangled photon pairs are generated from a broadband source based on spontaneous parametric down conversion in a periodically poled lithium niobate crystal using a double path setup employing a Michelson interferometer and active phase stabilisation. We test and compare demultiplexers based on various technologies and analyze the effect of their characteristics, such as losses and polarization dependence, on the quality of the distributed entanglement for three channel pairs of each demultiplexer. In all cases, we obtain a Bell inequality violation, whose value depends on the demultiplexer features. This demonstrates that entanglement can be distributed to at least three user pairs of a network from a single source. Additionally, we verify for the best demultiplexer that the violation is maintained when the pairs are distributed over a total channel attenuation corresponding to 20 km of optical fiber. These techniques are therefore suitable for resource-efficient practical implementations of entanglement-based quantum key distribution and other quantum communication network applications.

  14. Multi-user distribution of polarization entangled photon pairs

    SciTech Connect

    Trapateau, J.; Orieux, A.; Diamanti, E.; Zaquine, I.; Ghalbouni, J.

    2015-10-14

    We experimentally demonstrate multi-user distribution of polarization entanglement using commercial telecom wavelength division demultiplexers. The entangled photon pairs are generated from a broadband source based on spontaneous parametric down conversion in a periodically poled lithium niobate crystal using a double path setup employing a Michelson interferometer and active phase stabilisation. We test and compare demultiplexers based on various technologies and analyze the effect of their characteristics, such as losses and polarization dependence, on the quality of the distributed entanglement for three channel pairs of each demultiplexer. In all cases, we obtain a Bell inequality violation, whose value depends on the demultiplexer features. This demonstrates that entanglement can be distributed to at least three user pairs of a network from a single source. Additionally, we verify for the best demultiplexer that the violation is maintained when the pairs are distributed over a total channel attenuation corresponding to 20 km of optical fiber. These techniques are therefore suitable for resource-efficient practical implementations of entanglement-based quantum key distribution and other quantum communication network applications.

  15. Non-LTE profiles of the Al I autoionization lines. [for solar model atmospheres

    NASA Technical Reports Server (NTRS)

    Finn, G. D.; Jefferies, J. T.

    1974-01-01

    A non-LTE formulation is given for the transfer of radiation in the autoionizing lines of neutral aluminum at 1932 and 1936 A through both the Bilderberg and Harvard-Smithsonian model atmospheres. Numerical solutions for the common source function of these lines and their theoretical line profiles are calculated and compared with the corresponding LTE profiles. The results show that the non-LTE profiles provide a better match with the observations. They also indicate that the continuous opacity of the standard solar models should be increased in this wavelength region if the center-limb variations of observed and theoretical profiles of these lines are to be in reasonable agreement.

  16. Detailed Configuration Calculations for Non-LTE Modeling

    NASA Astrophysics Data System (ADS)

    Fontes, Christopher J.; Abdallah, Joseph, Jr.; Clark, Robert E. H.; Kilcrease, David P.

    1998-11-01

    We continue our work to explore the feasibility of creating detailed atomic models for radiation-hydrodynamics simulations of ICF applications. By further optimizing our atomic data codes we are able to create non-LTE models with a level of complexity approximately one order of magnitude greater (in size) than previously obtained. We present emissivities for gold which include on the order of 75,000 configurations per temperature-density point. The inclusion of additional configurations has yielded improved results for quantities such as the ion fraction distributions, but the question of spectral convergence is yet unanswered. The creation of still larger models will be discussed as well as comparison with experiment and other theories. The possibility of using these models for in-line simulations will also be discussed.

  17. Fully Relativistic Calculations for Non-LTE Modeling

    NASA Astrophysics Data System (ADS)

    Fontes, Christopher J.; Zhang, Hong Lin; Abdallah, Joseph, Jr.; Clark, Robert E. H.; Kilcrease, David P.

    1999-11-01

    A set of fully relativistic codes has been developed to calculate non-LTE, configuration-average atomic models for use in ICF simulations. The codes are based on the same architecture as that used by existing atomic data codes at Los Alamos such as CATS, ACE, GIPPER and FINE. Therefore the new codes are just as easily used in detailed configuration calculations, similar to work reported at previous meetings. In keeping with earlier work we provide sample calculations for some simple gold models. The effect of a fully relativistic treatment on quantities such as average charge state, ion fractions and emissivity will be reported. The possibility of applying the new codes to a very large number of configurations will also be discussed.

  18. A grid of LTE zero-metallicity stellar fluxes

    NASA Astrophysics Data System (ADS)

    Chávez, M.; Cardona, O.

    We present a grid of LTE theoretical spectral energy distributions (SEDs) of models composed of only H and He. The calculations were based on the codes developed by L. Auer and considered 71 atmospheric layers in hydrostatic and radiative equilibria. The SEDs consist on 46 wavelength points extending from the extreme ultraviolet to the infrared and cover the parameter space from 10000 to 140000K in effective temperature and 4.0-6.0 dex in surface gravity. The coarse coverage in wavelength makes the grid suitable for continuum studies since the Lyman and Balmer breaks at 912 and 3647 Å: respectively are among the most prominent features for the parameter space covered by the grid.

  19. A Hybrid Multiuser Detector Based on MMSE and AFSA for TDRS System Forward Link

    PubMed Central

    Yin, Zhendong; Liu, Xiaohui

    2014-01-01

    This study mainly focuses on multiuser detection in tracking and data relay satellite (TDRS) system forward link. Minimum mean square error (MMSE) is a low complexity multiuser detection method, but MMSE detector cannot achieve satisfactory bit error ratio and near-far resistance, whereas artificial fish swarm algorithm (AFSA) is expert in optimization and it can realize the global convergence efficiently. Therefore, a hybrid multiuser detector based on MMSE and AFSA (MMSE-AFSA) is proposed in this paper. The result of MMSE and its modified formations are used as the initial values of artificial fishes to accelerate the speed of global convergence and reduce the iteration times for AFSA. The simulation results show that the bit error ratio and near-far resistance performances of the proposed detector are much better, compared with MF, DEC, and MMSE, and are quite close to OMD. Furthermore, the proposed MMSE-AFSA detector also has a large system capacity. PMID:24883418

  20. Low-cost extrapolation method for maximal LTE radio base station exposure estimation: test and validation.

    PubMed

    Verloock, Leen; Joseph, Wout; Gati, Azeddine; Varsier, Nadège; Flach, Björn; Wiart, Joe; Martens, Luc

    2013-06-01

    An experimental validation of a low-cost method for extrapolation and estimation of the maximal electromagnetic-field exposure from long-term evolution (LTE) radio base station installations are presented. No knowledge on downlink band occupation or service characteristics is required for the low-cost method. The method is applicable in situ. It only requires a basic spectrum analyser with appropriate field probes without the need of expensive dedicated LTE decoders. The method is validated both in laboratory and in situ, for a single-input single-output antenna LTE system and a 2×2 multiple-input multiple-output system, with low deviations in comparison with signals measured using dedicated LTE decoders. PMID:23179190

  1. The Non-LTE Model of IR Emissions of Methane in the Titan's Atmosphere

    NASA Astrophysics Data System (ADS)

    Kutepov, Alexander; Rezac, Ladislav; Rey, Michael; Nikitin, Andrei; Boursier, Corinne

    2014-11-01

    Above about 400-450 km in Titan's atmosphere, the assumption of local thermodynamic equilibrium (LTE) breaks down for molecular vibrational levels of methane and various trace gases. Above this altitude non-LTE significantly impacts the formation of infrared ro-vibrational band emissions of these species observed in the limb viewing geometry. We present detailed model of the non-LTE in methane in the Titan's atmosphere based on a new extended database of the CH4 spectroscopic parameters as well as on the revised system of collisional V-T and V-V exchange rates. We analyze for a number of atmospheric models the vibrational temperatures of various CH4 levels and limb emissions, and compare them with those obtained for the HITRAN-2012 methane spectroscopic parameters. Implications for the non-LTE diagnostics of the Cassini CIRS and VIMS measurements are discussed.

  2. The Non-LTE Model of IR Emissions of Methane in the Titan'sAtmosphere

    NASA Astrophysics Data System (ADS)

    Kutepov, Alexander; Rezac, Ladislav; Feofilov, Artem; Rey, Michael; Nikitin, Andrei; Tyuterev, Vladimir

    2015-11-01

    Above about 400-450 km in Titan's atmosphere, the assumption of local thermodynamic equilibrium (LTE) breaks down for molecular vibrational levels of methane and various trace gases. Above this altitude non-LTE significantly impacts the formation of infrared ro-vibrational band emissions of these species observed in the limb viewing geometry. We present detailed model of the non-LTE in methane in the Titan's atmosphere based on a new extended database of the CH4 spectroscopic parameters calculated for this study. We analyze vibrational temperatures of various 12CH4 and 13CH4 levels as well as CH4 limb emissions in the 7.6 and 3.3 um spectral regions. The impact on these emissions of many weak one-quantum and combinational bands, which are missing in current databases, is studied. Implications for the non-LTE diagnostics of the Cassini CIRS and VIMS measurements are discussed.

  3. Sensor-Based Human Activity Recognition in a Multi-user Scenario

    NASA Astrophysics Data System (ADS)

    Wang, Liang; Gu, Tao; Tao, Xianping; Lu, Jian

    Existing work on sensor-based activity recognition focuses mainly on single-user activities. However, in real life, activities are often performed by multiple users involving interactions between them. In this paper, we propose Coupled Hidden Markov Models (CHMMs) to recognize multi-user activities from sensor readings in a smart home environment. We develop a multimodal sensing platform and present a theoretical framework to recognize both single-user and multi-user activities. We conduct our trace collection done in a smart home, and evaluate our framework through experimental studies. Our experimental result shows that we achieve an average accuracy of 85.46% with CHMMs.

  4. RBF multiuser detector with channel estimation capability in a synchronous MC-CDMA system.

    PubMed

    Ko, K; Choi, S; Kang, C; Hong, D

    2001-01-01

    The authors propose a multiuser detector with channel estimation capability using a radial basis function (RBF) network in a synchronous multicarrier-code division multiple access (MC-CDMA) system. The authors propose to connect an RBF network to the frequency domain to effectively utilize the frequency diversity. Simulations were performed over frequency-selective and multi-path fading channels. These simulations confirmed that the proposed receiver can be used both for the channel estimation and as a multi-user receiver, thus permitting an increase in the number of active users. PMID:18249987

  5. Application of syndrome based Turbo decoding with adaptive computational complexity in LTE downlink

    NASA Astrophysics Data System (ADS)

    Geldmacher, J.; Hueske, K.; Kosakowski, M.; Götze, J.

    2012-09-01

    This paper describes the application of an adaptive complexity decoder for the Long Term Evolution (LTE) downlink Turbo code. The proposed decoding approach is based on the block syndrome decoding principle and enables adaptive reduction of decoding effort depending on current SNR and iteration number with negligible influence on decoding performance. Numerical results in context of LTE downlink using typical mobile channels are used to demonstrate the efficiency of the approach.

  6. New computational method for non-LTE, the linear response matrix

    SciTech Connect

    Fournier, K. B.; Graziani, F. R.; Harte, J. A.; Libby, S. B.; More, R. M.; Rathkopf, J.; Zimmerman, G. B.

    1998-10-01

    We investigate non-local thermodynamic equilibrium atomic kinetics using nonequilibrium thermodynamics and linear response theory. This approach gives a rigorous general framework for exploiting results from non-LTE kinetic calculations and offers a practical data-tabulation scheme suitable for use in plasma simulation codes. We describe how this method has been implemented to supply a fast and accurate non-LTE option in Lasnex.

  7. The Fluids And Combustion Facility Combustion Integrated Rack And The Multi-User Droplet Combustion Apparatus: Microgravity Combustion Science Using Modular Multi-User Hardware

    NASA Technical Reports Server (NTRS)

    OMalley, Terence F.; Myhre, Craig A.

    2000-01-01

    The Fluids and Combustion Facility (FCF) is a multi-rack payload planned for the International Space Station (ISS) that will enable the study of fluid physics and combustion science in a microgravity environment. The Combustion Integrated Rack (CIR) is one of two International Standard Payload Racks of the FCF and is being designed primarily to support combustion science experiments. The Multi-user Droplet Combustion Apparatus (MDCA) is a multi-user apparatus designed to accommodate four different droplet combustion science experiments and is the first payload for CIR. The CIR will function independently until the later launch of the Fluids Integrated Rack component of the FCF. This paper provides an overview of the capabilities and the development status of the CIR and MDCA.

  8. Multi-User Space Link Extension (SLE) System

    NASA Technical Reports Server (NTRS)

    Perkins, Toby

    2013-01-01

    The Multi-User Space (MUS) Link Extension system, a software and data system, provides Space Link Extension (SLE) users with three space data transfer services in timely, complete, and offline modes as applicable according to standards defined by the Consultative Committee for Space Data Systems (CCSDS). MUS radically reduces the schedule, cost, and risk of implementing a new SLE user system, minimizes operating costs with a lights-out approach to SLE, and is designed to require no sustaining engineering expense during its lifetime unless changes in the CCSDS SLE standards, combined with new provider implementations, force changes. No software modification to MUS needs to be made to support a new mission. Any systems engineer with Linux experience can begin testing SLE user service instances with MUS starting from a personal computer (PC) within five days. For flight operators, MUS provides a familiar-looking Web page for entering SLE configuration data received from SLE. Operators can also use the Web page to back up a space mission's entire set of up to approximately 500 SLE service instances in less than five seconds, or to restore or transfer from another system the same amount of data from a MUS backup file in about the same amount of time. Missions operate each MUS SLE service instance independently by sending it MUS directives, which are legible, plain ASCII strings. MUS directives are usually (but not necessarily) sent through a TCP-IP (Transmission Control Protocol Internet Protocol) socket from a MOC (Mission Operations Center) or POCC (Payload Operations Control Center) system, under scripted control, during "lights-out" spacecraft operation. MUS permits the flight operations team to configure independently each of its data interfaces; not only commands and telemetry, but also MUS status messages to the MOC. Interfaces can use single- or multiple-client TCP/IP server sockets, TCP/IP client sockets, temporary disk files, the system log, or standard in

  9. Socialisation for Learning at a Distance in a 3-D Multi-User Virtual Environment

    ERIC Educational Resources Information Center

    Edirisingha, Palitha; Nie, Ming; Pluciennik, Mark; Young, Ruth

    2009-01-01

    This paper reports findings of a pilot study that examined the pedagogical potential of "Second Life" (SL), a popular three-dimensional multi-user virtual environment (3-D MUVE) developed by the Linden Lab. The study is part of a 1-year research and development project titled "Modelling of Secondlife Environments" (http://www.le.ac.uk/moose)…

  10. OPERATION OF THE OLD RIVER CONTROL PROJECT, ATCHAFALAYA BASIN: AN EVALUATION FROM MULTIUSE MANAGEMENT STANDPOINT

    EPA Science Inventory

    This report evaluated from a multiuse management standpoint the operation of the Old River Control Project. It was found that limiting diversions to the extent presently being considered by the Old River Control Project would effectively remove those wetlands that are presently f...

  11. Civic Participation among Seventh-Grade Social Studies Students in Multi-User Virtual Environments

    ERIC Educational Resources Information Center

    Zieger, Laura; Farber, Matthew

    2012-01-01

    Technological advances on the Internet now enable students to develop participation skills in virtual worlds. Similar to controlling a character in a video game, multi-user virtual environments, or MUVEs, allow participants to interact with others in synchronous, online settings. The authors of this study created a link between MUVEs and…

  12. A Multi-User Virtual Environment for Building and Assessing Higher Order Inquiry Skills in Science

    ERIC Educational Resources Information Center

    Ketelhut, Diane Jass; Nelson, Brian C.; Clarke, Jody; Dede, Chris

    2010-01-01

    This study investigated novel pedagogies for helping teachers infuse inquiry into a standards-based science curriculum. Using a multi-user virtual environment (MUVE) as a pedagogical vehicle, teams of middle-school students collaboratively solved problems around disease in a virtual town called River City. The students interacted with "avatars" of…

  13. First Eigenmode Transmission by High Efficient CSI Estimation for Multiuser Massive MIMO Using Millimeter Wave Bands

    PubMed Central

    Maruta, Kazuki; Iwakuni, Tatsuhiko; Ohta, Atsushi; Arai, Takuto; Shirato, Yushi; Kurosaki, Satoshi; Iizuka, Masataka

    2016-01-01

    Drastic improvements in transmission rate and system capacity are required towards 5th generation mobile communications (5G). One promising approach, utilizing the millimeter wave band for its rich spectrum resources, suffers area coverage shortfalls due to its large propagation loss. Fortunately, massive multiple-input multiple-output (MIMO) can offset this shortfall as well as offer high order spatial multiplexing gain. Multiuser MIMO is also effective in further enhancing system capacity by multiplexing spatially de-correlated users. However, the transmission performance of multiuser MIMO is strongly degraded by channel time variation, which causes inter-user interference since null steering must be performed at the transmitter. This paper first addresses the effectiveness of multiuser massive MIMO transmission that exploits the first eigenmode for each user. In Line-of-Sight (LoS) dominant channel environments, the first eigenmode is chiefly formed by the LoS component, which is highly correlated with user movement. Therefore, the first eigenmode provided by a large antenna array can improve the robustness against the channel time variation. In addition, we propose a simplified beamforming scheme based on high efficient channel state information (CSI) estimation that extracts the LoS component. We also show that this approximate beamforming can achieve throughput performance comparable to that of the rigorous first eigenmode transmission. Our proposed multiuser massive MIMO scheme can open the door for practical millimeter wave communication with enhanced system capacity. PMID:27399715

  14. Exploring Embedded Guidance and Self-Efficacy in Educational Multi-User Virtual Environments

    ERIC Educational Resources Information Center

    Nelson, Brian C.; Ketelhut, Diane Jass

    2008-01-01

    In this paper, we present the results of an exploratory study into the relationship between student self-efficacy and guidance use in a Multi-User Virtual Environment (MUVE) science curriculum project. We describe findings from a sample of middle school science students on the combined impact on learning of student self-efficacy in scientific…

  15. Exploring the Use of Individualized, Reflective Guidance in an Educational Multi-User Virtual Environment

    ERIC Educational Resources Information Center

    Nelson, Brian C.

    2007-01-01

    This study examines the patterns of use and potential impact of individualized, reflective guidance in an educational Multi-User Virtual Environment (MUVE). A guidance system embedded within a MUVE-based scientific inquiry curriculum was implemented with a sample of middle school students in an exploratory study investigating (a) whether access to…

  16. Implications of Placedness for Learning in Multi-User Virtual Environments

    ERIC Educational Resources Information Center

    Lim, Kenneth Y. T.

    2010-01-01

    This article considers some of the unique affordances that Multi-User Virtual Environments--in particular, Second Life--present to the design of learning environments. Drawing upon some preliminary experiences of acquainting teachers in several schools in Singapore with Second Life, specific attention is paid to the inherent spatiality of the…

  17. First Eigenmode Transmission by High Efficient CSI Estimation for Multiuser Massive MIMO Using Millimeter Wave Bands.

    PubMed

    Maruta, Kazuki; Iwakuni, Tatsuhiko; Ohta, Atsushi; Arai, Takuto; Shirato, Yushi; Kurosaki, Satoshi; Iizuka, Masataka

    2016-01-01

    Drastic improvements in transmission rate and system capacity are required towards 5th generation mobile communications (5G). One promising approach, utilizing the millimeter wave band for its rich spectrum resources, suffers area coverage shortfalls due to its large propagation loss. Fortunately, massive multiple-input multiple-output (MIMO) can offset this shortfall as well as offer high order spatial multiplexing gain. Multiuser MIMO is also effective in further enhancing system capacity by multiplexing spatially de-correlated users. However, the transmission performance of multiuser MIMO is strongly degraded by channel time variation, which causes inter-user interference since null steering must be performed at the transmitter. This paper first addresses the effectiveness of multiuser massive MIMO transmission that exploits the first eigenmode for each user. In Line-of-Sight (LoS) dominant channel environments, the first eigenmode is chiefly formed by the LoS component, which is highly correlated with user movement. Therefore, the first eigenmode provided by a large antenna array can improve the robustness against the channel time variation. In addition, we propose a simplified beamforming scheme based on high efficient channel state information (CSI) estimation that extracts the LoS component. We also show that this approximate beamforming can achieve throughput performance comparable to that of the rigorous first eigenmode transmission. Our proposed multiuser massive MIMO scheme can open the door for practical millimeter wave communication with enhanced system capacity. PMID:27399715

  18. From Multi-User Virtual Environment to 3D Virtual Learning Environment

    ERIC Educational Resources Information Center

    Livingstone, Daniel; Kemp, Jeremy; Edgar, Edmund

    2008-01-01

    While digital virtual worlds have been used in education for a number of years, advances in the capabilities and spread of technology have fed a recent boom in interest in massively multi-user 3D virtual worlds for entertainment, and this in turn has led to a surge of interest in their educational applications. In this paper we briefly review the…

  19. Multi-User Virtual Environments for Learning: Experience and Technology Design

    ERIC Educational Resources Information Center

    Di Blas, N.; Bucciero, A.; Mainetti, L.; Paolini, P.

    2012-01-01

    Multi-User Virtual Environments (MUVEs) are often used to support learning in formal and informal educational contexts. A technology-based educational experience consists of several elements: content, syllabus, roles, sequence of activities, assignments, assessment procedures, etc. that must be aligned with the affordances of the technologies to…

  20. Language Learning in Multi-User Virtual Environments: Using the Enter-the-Story Teaching Method

    ERIC Educational Resources Information Center

    Wong, Yin-Mei; Tan, Seng-Chee

    2009-01-01

    The authors propose using the Enter-the-Story teaching method for language learning in Multi-User Virtual Environments (MUVEs). A MUVE's immersive story-world imbued with rich cultural artifacts provides an appealing environment for young learners to learn a language by taking on roles in a story and describing their imaginative experience in the…

  1. Studying the Effectiveness of Multi-User Immersive Environments for Collaborative Evaluation Tasks

    ERIC Educational Resources Information Center

    Lorenzo, Carlos-Miguel; Sicilia, Miguel Angel; Sanchez, Salvador

    2012-01-01

    Massively Multiuser On-line Learning (MMOL) Platforms, often called "virtual learning worlds", constitute a still unexplored context for communication-enhanced learning, where synchronous communication skills in an explicit social setting enhance the potential of effective collaboration. In this paper, we report on an experimental study of…

  2. Teacher Perceptions of Learning Affordances of Multi-User Virtual Environments

    ERIC Educational Resources Information Center

    Gamage, Vimani; Tretiakov, Alexei; Crump, Barbara

    2011-01-01

    While the affordances of multi-user virtual environments (MUVEs) for teaching and learning are a subject of numerous experience reports, there is little research on educators' perceptions of various MUVE affordances claimed in the literature. We investigate the educators' perceptions of claimed MUVE affordances for learning by conducting in-depth…

  3. Design and Implementation of a 3D Multi-User Virtual World for Language Learning

    ERIC Educational Resources Information Center

    Ibanez, Maria Blanca; Garcia, Jose Jesus; Galan, Sergio; Maroto, David; Morillo, Diego; Kloos, Carlos Delgado

    2011-01-01

    The best way to learn is by having a good teacher and the best language learning takes place when the learner is immersed in an environment where the language is natively spoken. 3D multi-user virtual worlds have been claimed to be useful for learning, and the field of exploiting them for education is becoming more and more active thanks to the…

  4. Teacher Candidates' Views of a Multi-User Virtual Environment (MUVE)

    ERIC Educational Resources Information Center

    Sardone, Nancy B.; Devlin-Scherer, Roberta

    2008-01-01

    Multi-user virtual environments (MUVEs) are new to formal educational settings as teaching and learning tools but are growing in popularity. MUVEs simulate real-world problems. They have an ability to reach students in ways that are familiar as they resemble videogames where players assume roles, work in teams, and gather data. MUVEs include…

  5. The Role of Teacher, Student and ICT in Enhancing Student Engagement in Multiuser Virtual Environments

    ERIC Educational Resources Information Center

    Rappa, Natasha Anne; Yip, Daniel Kok Hoong; Baey, Shi Chen

    2009-01-01

    This paper reviews the teaching and learning practices and processes that were adopted in a study that incorporated multi-user virtual environments to support General Paper teaching and learning. The paper discusses the roles of the teacher, student and ICT in facilitating engaged learning. As this project is the first of its kind for the subject…

  6. A "Second Life" for Gross Anatomy: Applications for Multiuser Virtual Environments in Teaching the Anatomical Sciences

    ERIC Educational Resources Information Center

    Richardson, April; Hazzard, Matthew; Challman, Sandra D.; Morgenstein, Aaron M.; Brueckner, Jennifer K.

    2011-01-01

    This article describes the emerging role of educational multiuser virtual environments, specifically Second Life[TM], in anatomical sciences education. Virtual worlds promote inquiry-based learning and conceptual understanding, potentially making them applicable for teaching and learning gross anatomy. A short introduction to Second Life as an…

  7. Multi-User Virtual Environments for Education and Training? A Critical Review of "Second Life"

    ERIC Educational Resources Information Center

    Berge, Zane L., Ed.

    2008-01-01

    "Second Life" is a popular example of an immersive, three-dimensional, virtual world. Inhabitants of "Second Life" often describe their experiences in-world as having great social presence. Certainly there is a good deal of potential for education and training to occur in multi-user virtual environments (MUVEs), if designed properly, especially…

  8. Pre-coding method and apparatus for multiple source or time-shifted single source data and corresponding inverse post-decoding method and apparatus

    NASA Technical Reports Server (NTRS)

    Yeh, Pen-Shu (Inventor)

    1997-01-01

    A pre-coding method and device for improving data compression performance by removing correlation between a first original data set and a second original data set, each having M members, respectively. The pre-coding method produces a compression-efficiency-enhancing double-difference data set. The method and device produce a double-difference data set, i.e., an adjacent-delta calculation performed on a cross-delta data set or a cross-delta calculation performed on two adjacent-delta data sets, from either one of (1) two adjacent spectral bands coming from two discrete sources, respectively, or (2) two time-shifted data sets coming from a single source. The resulting double-difference data set is then coded using either a distortionless data encoding scheme (entropy encoding) or a lossy data compression scheme. Also, a post-decoding method and device for recovering a second original data set having been represented by such a double-difference data set.

  9. Pre-coding method and apparatus for multiple source or time-shifted single source data and corresponding inverse post-decoding method and apparatus

    NASA Technical Reports Server (NTRS)

    Yeh, Pen-Shu (Inventor)

    1998-01-01

    A pre-coding method and device for improving data compression performance by removing correlation between a first original data set and a second original data set, each having M members, respectively. The pre-coding method produces a compression-efficiency-enhancing double-difference data set. The method and device produce a double-difference data set, i.e., an adjacent-delta calculation performed on a cross-delta data set or a cross-delta calculation performed on two adjacent-delta data sets, from either one of (1) two adjacent spectral bands coming from two discrete sources, respectively, or (2) two time-shifted data sets coming from a single source. The resulting double-difference data set is then coded using either a distortionless data encoding scheme (entropy encoding) or a lossy data compression scheme. Also, a post-decoding method and device for recovering a second original data set having been represented by such a double-difference data set.

  10. Non-LTE analysis of copper abundances for the two distinct halo populations in the solar neighborhood

    NASA Astrophysics Data System (ADS)

    Yan, H. L.; Shi, J. R.; Nissen, P. E.; Zhao, G.

    2016-01-01

    Context. Two distinct halo populations were found in the solar neighborhood by a series of works. They can be clearly separated by [α/Fe] and several other elemental abundance ratios including [Cu/Fe]. Very recently, a non-local thermodynamic equilibrium (non-LTE) study revealed that relatively large departures exist between LTE and non-LTE results in copper abundance analysis. The study also showed that non-LTE effects of neutral copper vary with stellar parameters and thus affect the [Cu/Fe] trend. Aims: We aim to derive the copper abundances for the stars from the sample of Nissen & Schuster (2010) with both LTE and non-LTE calculations. Based on our results, we study the non-LTE effects of copper and investigate whether the high-α population can still be distinguished from the low-α population in the non-LTE [Cu/Fe] results. Methods: Our differential abundance ratios are derived from the high-resolution spectra collected from VLT/UVES and NOT/FIES spectrographs. Applying the MAFAGS opacity sampling atmospheric models and spectrum synthesis method, we derive the non-LTE copper abundances based on the new atomic model with current atomic data obtained from both laboratory and theoretical calculations. Results: The copper abundances determined from non-LTE calculations are increased by 0.01 to 0.2 dex depending on the stellar parameters compared with the LTE results. The non-LTE [Cu/Fe] trend is much flatter than the LTE one in the metallicity range -1.6 < [ Fe / H ] < -0.8. Taking non-LTE effects into consideration, the high- and low-α stars still show distinguishable copper abundances, which appear even more clear in a diagram of non-LTE [Cu/Fe] versus [Fe/H]. Conclusions: The non-LTE effects are strong for copper, especially in metal-poor stars. Our results confirmed that there are two distinct halo populations in the solar neighborhood. The dichotomy in copper abundance is a peculiar feature of each population, suggesting that they formed in different

  11. Spectroscopic Non-LTE Modeling of Highly Charged Gold Plasma

    NASA Astrophysics Data System (ADS)

    Dasgupta, A.; Ouart, N. D.; Giuliani, J. L.; Obenschain, S. P.; Clark, R. W.; Aglitskiy, Y.

    2013-10-01

    An X-ray spectrometer is under development at the Naval Research Laboratory (NRL) to investigate emissions from gold targets irradiated by the NIKE KrF facility. This effort is in support of the indirect drive campaign on the National Ignition Facility (NIF). To analyze and interpret the NIKE experimental spectra, we are theoretically exploring line emissions from a gold plasma in the M-band, i.e., 1.5 to 3.5 keV. We employ a detailed Non-LTE atomic model for ions near Ni-like gold by including an adequate number of configurations to obtain spectroscopic details in this range. The atomic states are coupled both collisionally and radiatively, including all dominant atomic processes that have significant contributions to the ionization and emitted synthetic spectra. In particular, we will investigate the effect of dielectronic recombination, which can have a dominant effect on level populations for highly ionized high Z plasmas. Since the radiation field can affect level populations through photoionization and photoexcitation, our collisional-radiative model will include non-local radiation transport. The line shapes of the strong overlapping lines will be resolved by a multifrequency radiation transport method. Synthetic spectra with radiation transport, including resonant photo-pumping, will be generated for realistic densities and temperatures to compare with the NIKE data. Work supported by DOE/NNSA.

  12. The theory research of multi-user quantum access network with Measurement Device Independent quantum key distribution

    NASA Astrophysics Data System (ADS)

    Ji, Yi-Ming; Li, Yun-Xia; Shi, Lei; Meng, Wen; Cui, Shu-Min; Xu, Zhen-Yu

    2015-10-01

    Quantum access network can't guarantee the absolute security of multi-user detector and eavesdropper can get access to key information through time-shift attack and other ways. Measurement-device-independent quantum key distribution is immune from all the detection attacks, and accomplishes the safe sharing of quantum key. In this paper, that Measurement-device-independent quantum key distribution is used in the application of multi-user quantum access to the network is on the research. By adopting time-division multiplexing technology to achieve the sharing of multiuser detector, the system structure is simplified and the security of quantum key sharing is acquired.

  13. Non-LTE line formation of Fe in late-type stars - III. 3D non-LTE analysis of metal-poor stars

    NASA Astrophysics Data System (ADS)

    Amarsi, A. M.; Lind, K.; Asplund, M.; Barklem, P. S.; Collet, R.

    2016-08-01

    As one of the most important elements in astronomy, iron abundance determinations need to be as accurate as possible. We investigate the accuracy of spectroscopic iron abundance analyses using archetypal metal-poor stars. We perform detailed 3D non-LTE radiative transfer calculations based on 3D hydrodynamic STAGGER model atmospheres, and employ a new model atom that includes new quantum-mechanical neutral hydrogen collisional rate coefficients. With the exception of the red giant HD122563, we find that the 3D non-LTE models achieve Fe I/Fe II excitation and ionization balance as well as not having any trends with equivalent width to within modelling uncertainties of 0.05 dex, all without having to invoke any microturbulent broadening; for HD122563 we predict that the current best parallax-based surface gravity is overestimated by 0.5 dex. Using a 3D non-LTE analysis, we infer iron abundances from the 3D model atmospheres that are roughly 0.1 dex higher than corresponding abundances from 1D MARCS model atmospheres; these differences go in the same direction as the non-LTE effects themselves.We make available grids of departure coefficients, equivalent widths and abundance corrections, calculated on 1D MARCS model atmospheres and horizontally- and temporally-averaged 3D STAGGER model atmospheres.

  14. Untersuchung der Störwirkung von LTE auf SRD Anwendungen bei 868 MHz

    NASA Astrophysics Data System (ADS)

    Welpot, M.; Wunderlich, S.; Gaspard, I.

    2014-11-01

    Moderne Hausautomatisierungssysteme, Alarmanlagen oder auch Funk-Zugangssysteme in Haus und Automobil setzen auf frei nutzbare Frequenzen in ISM/SRD-Bändern. Die rasante Zunahme an privaten und kommerziell genutzten Applikationen im SRD-Band bei 868 MHz und der Ausbau der LTE-Mobilfunknetze im Frequenzbereich unterhalb von 1 GHz ("Digital Dividend") wirft zunehmend die Frage nach der Funkverträglichkeit dieser Systeme untereinander auf. Während die SRD-Funkmodule auf eine geringe Sendeleistung von ~ +14 dBm beschränkt sind (Ralf and Thomas, 2009), beträgt die maximale LTE-Sendeleistung im Uplink nach (ETSI-Norm, 2011) +23 dBm. Zusammen mit der Einführung von LTE im Frequenzbereich unterhalb 1 GHz als DSL-Ersatz vor allem in ländlichen Gebieten, ergibt sich damit als mögliches Störszenario, dass durch die Aussendung des LTE-Endgerätes im Bereich von ca. 850 MHz die SRD-Funkverbindungen bei 868 MHz insbesondere dann gestört werden, wenn die Antennen beider Funksysteme räumlich nahe zueinander angeordnet sind und folglich nur eine geringe zusätzliche Entkopplung der Systeme bieten. In der vorliegenden Arbeit wird das LTE-Störpotential auf SRD-Empfänger praxisnah untersucht.

  15. Rotational non-LTE in HCN in the thermosphere of Titan: Implications for the radiative cooling

    NASA Astrophysics Data System (ADS)

    Rezac, L.; Kutepov, A. A.; Faure, A.; Hartogh, P.; Feofilov, A. G.

    2013-07-01

    Context. The thermal structure of Titan's thermosphere is determined by the balance between several heating and cooling processes. These processes must be accurately modeled to correctly interpret the available measurements and enhance our understanding of the formation and evolution of this atmosphere. One of the most important thermospheric cooling process for Titan is emission in the HCN rotational band. Aims: We aim to determine the validity of local thermodynamic equilibrium (LTE) for the HCN rotational distribution in the thermosphere of Titan and the impact of its breakdown on the HCN radiative cooling rate in the thermosphere. Methods: A general non-LTE radiative transfer code for rotational lines based on the accelerated lambda iteration (ALI) was used to calculate the excitation of HCN rotational levels in Titan's atmosphere. These level populations were then used to calculate the associated cooling rate. Results: We show that the common assumption in the models of Titan's thermospheric energy balance, namely the LTE distribution of rotational lines of HCN, is generally not valid above about 1100 km, or ~0.025 nbar, which will affect the derived thermospheric cooling rates. The effect of non-LTE is to reduce the cooling rate to 15% of the LTE value at around the exobase altitudes depending on the given density of HCN and collisional partners (N2, CH4, H2, and electrons). Since collision state-to-state quenching rates of HCN rotational levels are poorly known, a sensitivity analysis of our results to these rates is also presented.

  16. A non-LTE treatment of beryllium lines - Misidentification of the solar Be I feature at 2650 A

    NASA Technical Reports Server (NTRS)

    Shipman, H. L.; Auer, L. H.

    1979-01-01

    The formation of beryllium lines, with particular reference to the solar Be spectrum, is investigated in a non-LTE context with a 25-level model atom in which 15 levels are allowed to depart from LTE. In some transitions, particularly the Be I 2650-A line, the non-LTE effects can be quite dramatic, changing the deduced abundances by a factor of 4. Based on the non-LTE calculations and Copernicus observations of other stars, it is found that a solar spectral feature at 2650 A, previously identified by numerous investigators as a Be I line, cannot be produced by Be I. Non-LTE effects on the Be II 3131-A line, used for most Be abundance determinations in the literature, are small by comparison.

  17. 3D Multi-Level Non-LTE Radiative Transfer for the CO Molecule

    NASA Astrophysics Data System (ADS)

    Berkner, A.; Schweitzer, A.; Hauschildt, P. H.

    2015-01-01

    The photospheres of cool stars are both rich in molecules and an environment where the assumption of LTE can not be upheld under all circumstances. Unfortunately, detailed 3D non-LTE calculations involving molecules are hardly feasible with current computers. For this reason, we present our implementation of the super level technique, in which molecular levels are combined into super levels, to reduce the number of unknowns in the rate equations and, thus, the computational effort and memory requirements involved, and show the results of our first tests against the 1D implementation of the same method.

  18. Novel wideband MIMO antennas that can cover the whole LTE spectrum in handsets and portable computers.

    PubMed

    Sanad, Mohamed; Hassan, Noha

    2014-01-01

    A dual resonant antenna configuration is developed for multistandard multifunction mobile handsets and portable computers. Only two wideband resonant antennas can cover most of the LTE spectrums in portable communication equipment. The bandwidth that can be covered by each antenna exceeds 70% without using any matching or tuning circuits, with efficiencies that reach 80%. Thus, a dual configuration of them is capable of covering up to 39 LTE (4G) bands besides the existing 2G and 3G bands. 2×2 MIMO configurations have been also developed for the two wideband antennas with a maximum isolation and a minimum correlation coefficient between the primary and the diversity antennas. PMID:24558322

  19. Sediment Contaminants and Infauna Associated with Recreational Boating Structures in a Multi-Use Marine Park

    PubMed Central

    Sim, Vivian X. Y.; Dafforn, Katherine A.; Simpson, Stuart L.; Kelaher, Brendan P.; Johnston, Emma L.

    2015-01-01

    Multi-use marine parks achieve conservation through spatial management of activities. Zoning of marine parks in New South Wales, Australia, includes high conservation areas and special purpose zones (SPZ) where maritime activities are concentrated. Although such measures geographically constrain anthropogenic impacts, we have limited understanding of potential ecological effects. We assessed sediment communities and contaminants adjacent to boating infrastructure (boat ramps, jetties and a marina) in a SPZ from the Clyde Estuary in Batemans Marine Park. Metal concentrations and fines content were elevated at boating structures compared to reference sites. Species richness was higher at sites with boating structures, where capitellid polychaetes and nematodes dominated the communities. Changes associated with boating structures were localised and did not extend beyond breakwalls or to reference sites outside the SPZ. The study highlights the benefits of appropriate zoning in a multi-use marine park and the potential to minimise stress on pristine areas through the application of spatial management. PMID:26086427

  20. Sediment Contaminants and Infauna Associated with Recreational Boating Structures in a Multi-Use Marine Park.

    PubMed

    Sim, Vivian X Y; Dafforn, Katherine A; Simpson, Stuart L; Kelaher, Brendan P; Johnston, Emma L

    2015-01-01

    Multi-use marine parks achieve conservation through spatial management of activities. Zoning of marine parks in New South Wales, Australia, includes high conservation areas and special purpose zones (SPZ) where maritime activities are concentrated. Although such measures geographically constrain anthropogenic impacts, we have limited understanding of potential ecological effects. We assessed sediment communities and contaminants adjacent to boating infrastructure (boat ramps, jetties and a marina) in a SPZ from the Clyde Estuary in Batemans Marine Park. Metal concentrations and fines content were elevated at boating structures compared to reference sites. Species richness was higher at sites with boating structures, where capitellid polychaetes and nematodes dominated the communities. Changes associated with boating structures were localised and did not extend beyond breakwalls or to reference sites outside the SPZ. The study highlights the benefits of appropriate zoning in a multi-use marine park and the potential to minimise stress on pristine areas through the application of spatial management. PMID:26086427

  1. Service description of communication systems supporting multi-media multi-user applications

    NASA Astrophysics Data System (ADS)

    Heijenk, G. J.; Hou, X.; Niemegeers, I. G.

    The paper presents a service description of communication systems supporting multi-media multi-user applications. In particular, it focuses on service elements related to the call control. The service description specifies the functional behavior of the communication system as a whole. It can be used as a common reference in the next design stages, e.g., in the protocol design and implementation of both Customer Premises Networks and public telecommunication networks. After discussing the requirements of multi-media multi-user applications, a call model is presented. This model creates an abstract view of those aspects of the call relevant for the design and helps us in structuring the service. Only those service elements of a communication system that are related to the call establishment, modification and termination are fully specified by describing service primitives, their parameters and temporal ordering constraints.

  2. Soft-PIC multiuser detection in MC-CDMA uplink system

    NASA Astrophysics Data System (ADS)

    Guo, Li-Li; Yuan, Bing-Bing

    2005-06-01

    It is necessary for an MC-CDMA uplink receiver to employ MUD (multiuser detection) in a frequency selective fading channel. After analyzing the algorithm of PIC (parallel interference cancellation) MUD, a novel MUD scheme, Soft-PIC (soft parallel interference cancellation) is proposed. Based on the reliability of each detected user signal in the former stage, this Soft-PIC detection scheme substitutes a soft decision of the variable for the hard decision in PIC scheme. Compared with the PIC scheme, it can reconstruct the interference signals more accurately and eliminate MAI (multiple access interference) in a more efficient way. PIC is one of the most practical schemes in numerous multiuser detection technologies. However, Soft-PIC as an improved PIC scheme deserves further study.

  3. Blind CMA-Based Asynchronous Multiuser Detection Using Generalized Sidelobe Canceller with Decision Feedback

    NASA Astrophysics Data System (ADS)

    Chang, Ann-Chen; Jen, Chih-Wei

    This letter deals with blind multiuser detection based on the multi-channel linearly constrained constant modulus algorithm (MLCCMA) for asynchronous code division multiple access (CDMA) systems over frequency-selective Rayleigh fading channels. In conjunction with the decision-feedback generalized sidelobe canceller (DFGSC), we present an efficient approach to combat multiple access interference and intersymbol interference. Computer simulations confirm that the proposed MLCCMA-based DFGSC can significantly speed up convergence and improve the output performance.

  4. OpenGL in Multi-User Web-Based Applications

    NASA Astrophysics Data System (ADS)

    Szostek, K.; Piórkowski, A.

    In this article construction and potential of OpenGL multi-user web-based application are presented. The most common technologies like: .NET ASP, Java and Mono were used with specific OpenGL libraries to visualize tree-dimensional medical data. The most important conclusion of this work is that server side applications can easily take advantage of fast GPU and produce efficient results of advanced computation just like the visualization.

  5. A multiuser detector based on artificial bee colony algorithm for DS-UWB systems.

    PubMed

    Yin, Zhendong; Liu, Xiaohui; Wu, Zhilu

    2013-01-01

    Artificial Bee Colony (ABC) algorithm is an optimization algorithm based on the intelligent behavior of honey bee swarm. The ABC algorithm was developed to solve optimizing numerical problems and revealed premising results in processing time and solution quality. In ABC, a colony of artificial bees search for rich artificial food sources; the optimizing numerical problems are converted to the problem of finding the best parameter which minimizes an objective function. Then, the artificial bees randomly discover a population of initial solutions and then iteratively improve them by employing the behavior: moving towards better solutions by means of a neighbor search mechanism while abandoning poor solutions. In this paper, an efficient multiuser detector based on a suboptimal code mapping multiuser detector and artificial bee colony algorithm (SCM-ABC-MUD) is proposed and implemented in direct-sequence ultra-wideband (DS-UWB) systems under the additive white Gaussian noise (AWGN) channel. The simulation results demonstrate that the BER and the near-far effect resistance performances of this proposed algorithm are quite close to those of the optimum multiuser detector (OMD) while its computational complexity is much lower than that of OMD. Furthermore, the BER performance of SCM-ABC-MUD is not sensitive to the number of active users and can obtain a large system capacity. PMID:23983638

  6. Color coded multiple access scheme for bidirectional multiuser visible light communications in smart home technologies

    NASA Astrophysics Data System (ADS)

    Tiwari, Samrat Vikramaditya; Sewaiwar, Atul; Chung, Yeon-Ho

    2015-10-01

    In optical wireless communications, multiple channel transmission is an attractive solution to enhancing capacity and system performance. A new modulation scheme called color coded multiple access (CCMA) for bidirectional multiuser visible light communications (VLC) is presented for smart home applications. The proposed scheme uses red, green and blue (RGB) light emitting diodes (LED) for downlink and phosphor based white LED (P-LED) for uplink to establish a bidirectional VLC and also employs orthogonal codes to support multiple users and devices. The downlink transmission for data user devices and smart home devices is provided using red and green colors from the RGB LEDs, respectively, while uplink transmission from both types of devices is performed using the blue color from P-LEDs. Simulations are conducted to verify the performance of the proposed scheme. It is found that the proposed bidirectional multiuser scheme is efficient in terms of data rate and performance. In addition, since the proposed scheme uses RGB signals for downlink data transmission, it provides flicker-free illumination that would lend itself to multiuser VLC system for smart home applications.

  7. RACOON: a multiuser QoS design for mobile wireless body area networks.

    PubMed

    Cheng, Shihheng; Huang, Chingyao; Tu, Chun Chen

    2011-10-01

    In this study, Random Contention-based Resource Allocation (RACOON) medium access control (MAC) protocol is proposed to support the quality of service (QoS) for multi-user mobile wireless body area networks (WBANs). Different from existing QoS designs that focus on a single WBAN, a multiuser WBAN QoS should further consider both inter-WBAN interference and inter-WBAN priorities. Similar problems have been studied in both overlapped wireless local area networks (WLANs) and Bluetooth piconets that need QoS supports. However, these solutions are designed for non-medical transmissions that do not consider any priority scheme for medical applications. Most importantly, these studies focus on only static or low mobility networks. Network mobility of WBANs will introduce unnecessary inter-network collisions and energy waste, which are not considered by these solutions. The proposed multiuser-QoS protocol, RACOON, simultaneously satisfies the inter WBAN QoS requirements and overcomes the performance degradation caused by WBAN mobility. Simulation results verify that RACOON provides better latency and energy control, as compared with WBAN QoS protocols without considering the inter-WBAN requirements. PMID:21465185

  8. DEEP SPACE: High Resolution VR Platform for Multi-user Interactive Narratives

    NASA Astrophysics Data System (ADS)

    Kuka, Daniela; Elias, Oliver; Martins, Ronald; Lindinger, Christopher; Pramböck, Andreas; Jalsovec, Andreas; Maresch, Pascal; Hörtner, Horst; Brandl, Peter

    DEEP SPACE is a large-scale platform for interactive, stereoscopic and high resolution content. The spatial and the system design of DEEP SPACE are facing constraints of CAVETM-like systems in respect to multi-user interactive storytelling. To be used as research platform and as public exhibition space for many people, DEEP SPACE is capable to process interactive, stereoscopic applications on two projection walls with a size of 16 by 9 meters and a resolution of four times 1080p (4K) each. The processed applications are ranging from Virtual Reality (VR)-environments to 3D-movies to computationally intensive 2D-productions. In this paper, we are describing DEEP SPACE as an experimental VR platform for multi-user interactive storytelling. We are focusing on the system design relevant for the platform, including the integration of the Apple iPod Touch technology as VR control, and a special case study that is demonstrating the research efforts in the field of multi-user interactive storytelling. The described case study, entitled "Papyrate's Island", provides a prototypical scenario of how physical drawings may impact on digital narratives. In this special case, DEEP SPACE helps us to explore the hypothesis that drawing, a primordial human creative skill, gives us access to entirely new creative possibilities in the domain of interactive storytelling.

  9. User Acceptance of Long-Term Evolution (LTE) Services: An Application of Extended Technology Acceptance Model

    ERIC Educational Resources Information Center

    Park, Eunil; Kim, Ki Joon

    2013-01-01

    Purpose: The aim of this paper is to propose an integrated path model in order to explore user acceptance of long-term evolution (LTE) services by examining potential causal relationships between key psychological factors and user intention to use the services. Design/methodology/approach: Online survey data collected from 1,344 users are analysed…

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

    SciTech Connect

    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.

  11. Non-LTE effects on the strength of the Lyman edge in quasar accretion disks

    NASA Technical Reports Server (NTRS)

    Stoerzer, H.; Hauschildt, P. H.; Allard, F.

    1994-01-01

    We have calculated UV/EUV (300 A which is less than or equal to lambda which is less than or equal to 1500 A) continuous energy distributions of accretion disks in the centers of active galactic nuclei (AGNs) for disk luminosities in the range 0.1 L(sub Edd) less than or equal to L(sub acc) less than 1.0 L(sub Edd) and central masses ranging from 10(exp 8) solar mass to 10(exp 9) solar mass. The vertical gas pressure structure of the disk and the disk height are obtained analytically; the temperature stratification and the resulting continuum radiation fields are calculated numerically. We have included non-Local Thermodynamic Equilibrium (LTE) effects of both the ionization equilibrium and the level populations of hydrogen and helium. We show that these non-LTE effects reduce the strength of the Lyman edge when comapred to the LTE case. In non-LTE we find that the edge can be weakly in emission or absorption for disks seen face-on, depending on the disk parameters.

  12. Inspiring Equal Contribution and Opportunity in a 3D Multi-User Virtual Environment: Bringing Together Men Gamers and Women Non-Gamers in Second Life[R

    ERIC Educational Resources Information Center

    deNoyelles, Aimee; Seo, Kay Kyeong-Ju

    2012-01-01

    A 3D multi-user virtual environment holds promise to support and enhance student online learning communities due to its ability to promote global synchronous interaction and collaboration, rich multisensory experience and expression, and elaborate design capabilities. Second Life[R], a multi-user virtual environment intended for adult users 18 and…

  13. Multi-user multiplexed scheme for decoding modulated-encoded sequential information

    NASA Astrophysics Data System (ADS)

    Mosso, Fabian; Tebaldi, Myrian; Barrera, John Fredy; Bolognini, Néstor; Torroba, Roberto

    2011-08-01

    Encrypting procedures with multiplexed operations exhibit an inherent noise. We presented options to avoid background noise arising from the non-decoded images. We have a coding mask corresponding to each single input object, thus resulting in a static decrypting mechanism. Besides, if we manage the spatial destination of each decoded output, then we avoid the noise superposition. In those schemes, the displaying output order was irrelevant. However, when we face a sequence of events including multi-users, we need to develop another strategy. We present a multi-user encrypting scheme with a single encoding mask that removes the background noise, also showing the decrypted data in a prescribed sequence. The multiplexing scheme is based on the 4f double random phase encryption architecture and a theta modulation method, which consists in superposing each encrypted information with a determined sinusoidal grating. Afterwards we proceed to the completely encoded data multiplexing. In a multi-user scheme, we employ different encrypting masks in the 4f optical setup for each user, and the same mask is employed for the user sequence. We store the encrypted data in the single medium. After a Fourier transform operation and an appropriate filtering procedure, we reach the sequence of isolated encrypted spots corresponding to the right user. With the aid of the pertaining decoding mask, the user can decrypt the sequence. We avoid the noise by the appropriate choice of the modulating gratings pitch as to elude the overlapping of spots at the Fourier plane, which is the cause of information degradation.

  14. Assessing the existence of non-LTE behavior in aluminum K-shell diagnostic lines from dynamic hohlraum driven experiments

    NASA Astrophysics Data System (ADS)

    Sherrill, M. E.

    2015-11-01

    We describe in this work a study designed to obtain insight into the sensitivity of foil targets driven out of local thermodynamic equilibrium (LTE) by an idealized dynamic hohlraum during its brightest phase. This work is motivated by a perceived over-prediction of the plasma temperature by current LTE spectral modeling of opacity experiments performed by Bailey et al at the Sandia Z facility. Although several aspects of this modeling study parallel the SNL/LANL opacity experiments, this work is primarily intended to gain insight into radiatively over-driven systems. The results from this idealized study suggest that a non-LTE population distribution with qualities similar to an LTE distribution at higher material temperatures are possible, and therefore support a further theoretical investigation with experimental parameters.

  15. Evidence of non-LTE Effects in Mesospheric Water Vapor from Spectrally-Resolved Emissions Observed by CIRRIS-1A

    NASA Technical Reports Server (NTRS)

    Zhou, D. K.; Mlynczak, M. G.; Lopez-Puertas, M.; Zaragoza, G.

    1999-01-01

    Evidence of non-LTE effects in mesospheric water vapor as determined by infrared spectral emission measurements taken from the space shuttle is reported. A cryogenic Michelson interferometer in the CIRRIS-1A shuttle payload yielded high quality, atmospheric infrared spectra. These measurements demonstrate the enhanced daytime emissions of H2O (020-010) which are the result of non-LTE processes and in agreement with non-LTE models. The radiance ratios of H2O (010 to 000) and (020 to 010) Q(1) transitions during daytime are compared with non-LTE model calculations to assess the vibration-to-vibration exchange rate between H2O and O2 in the mesosphere. An exchange rate of 1.2 x 10(exp -12)cc/s is derived.

  16. Demonstration of high-speed multi-user multi-carrier CDMA visible light communication

    NASA Astrophysics Data System (ADS)

    Yang, Chao; Wang, Yuanquan; Wang, Yiguang; Huang, Xingxing; Chi, Nan

    2015-02-01

    We experimentally demonstrated a high-speed multi-user multi-carrier code-division multiple access (MC-CDMA) visible light communication (VLC) system. By employing a commercially available red light emitting diode (LED) and an avalanche photo diode (APD), we achieved a 16-user VLC system enabled by MC-CDMA, pre- and post-equalization, with an overall bit rate of 750 Mb/s over 1.5 m free-space transmission. The measured bit error ratio (BER) of each user is below the 7% pre-forward-error-correction (pre-FEC) threshold of 3.8×10-3.

  17. Robots, multi-user virtual environments and healthcare: synergies for future directions.

    PubMed

    Moon, Ajung; Grajales, Francisco J; Van der Loos, H F Machiel

    2011-01-01

    The adoption of technology in healthcare over the last twenty years has steadily increased, particularly as it relates to medical robotics and Multi-User Virtual Environments (MUVEs) such as Second Life. Both disciplines have been shown to improve the quality of care and have evolved, for the most part, in isolation from each other. In this paper, we present four synergies between medical robotics and MUVEs that have the potential to decrease resource utilization and improve the quality of healthcare delivery. We conclude with some foreseeable barriers and future research directions for researchers in these fields. PMID:21335746

  18. Characterization of dual-polarization LTE radio over a free-space optical turbulence channel.

    PubMed

    Bohata, J; Zvanovec, S; Korinek, T; Mansour Abadi, M; Ghassemlooy, Z

    2015-08-10

    A dual polarization (DP) radio over a free-space optical (FSO) communication link using a long-term evolution (LTE) radio signal is proposed and analyzed under different turbulence channel conditions. Radio signal transmission over the DP FSO channel is experimentally verified by means of error vector magnitude (EVM) statistics. We demonstrate that such a system, employing a 64 quadrature amplitude modulation at the frequency bands of 800 MHz and 2.6 GHz, evinces reliability with <8% of EVM in a turbulent channel. Based on the results, we show that transmitting the LTE signal over the FSO channel is a potential solution for last-mile access or backbone networks, when using multiple-input multiple-output based DP signals. PMID:26368379

  19. Limb-darkening coefficients from line-blanketed non-LTE hot-star model atmospheres

    NASA Astrophysics Data System (ADS)

    Reeve, D. C.; Howarth, I. D.

    2016-02-01

    We present grids of limb-darkening coefficients computed from non-local thermodynamic equilibrium (non-LTE), line-blanketed TLUSTY model atmospheres, covering effective-temperature and surface-gravity ranges of 15-55 kK and 4.75 dex (cgs) down to the effective Eddington limit, at 2×, 1×, 0.5× (Large Magellanic Cloud), 0.2× (Small Magellanic Cloud), and 0.1× solar. Results are given for the Bessell UBVRICJKHL, Sloan ugriz, Strömgren ubvy, WFCAM ZYJHK, Hipparcos, Kepler, and Tycho passbands, in each case characterized by several different limb-darkening `laws'. We examine the sensitivity of limb darkening to temperature, gravity, metallicity, microturbulent velocity, and wavelength, and make a comparison with LTE models. The dependence on metallicity is very weak, but limb darkening is a moderately strong function of log g in this temperature regime.

  20. Accurate Collisional Cross-Sections: Important Non-Lte Input Data

    NASA Astrophysics Data System (ADS)

    Mashonkina, L.

    2010-11-01

    Non-LTE modelling for a particular atom requires accurate collisional excitation and ionization cross-sections for the entire system of transitions in the atom. This review concerns with inelastic collisions with electrons and neutral hydrogen atoms. For the selected atoms, H i and Ca ii, comparisons are made between electron impact excitation rates from ab initio calculations and various theoretical approximations. The effect of the use of modern data on non-LTE modelling is shown. For most transitions and most atoms, hydrogen collisional rates are calculated using a semi-empirical modification of the classical Thomson formula for ionization by electrons. Approaches used to estimate empirically the efficiency of hydrogenic collisions in the statistical equilibrium of atoms are reviewed. This research was supported by the Deutsche Forschungsgemeinschaft with grant 436 RUS 17/13/07.

  1. TD-LTE Wireless Private Network QoS Transmission Protection

    NASA Astrophysics Data System (ADS)

    Zhang, Jianming; Cheng, Chao; Wu, Zanhong

    With the commencement of construction of the smart grid, the demand power business for reliability and security continues to improve, the reliability transmission of power TD-LTE Wireless Private Network are more and more attention. For TD-LTE power private network, it can provide different QoS services according to the user's business type, to protect the reliable transmission of business. This article describes in detail the AF module of PCC in the EPC network, specifically introduces set up AF module station and QoS mechanisms in the EPS load, fully considers the business characteristics of the special power network, establishing a suitable architecture for mapping QoS parameters, ensuring the implementation of each QoS business. Through using radio bearer management, we can achieve the reliable transmission of each business on physical channel.

  2. Construction of non-LTE model atmospheres using approximate lambda operators

    NASA Astrophysics Data System (ADS)

    Werner, K.

    1986-06-01

    A new method of calculating model atmospheres for hot stars subject to constraints of radiative, hydrostatic and statistical equilibrium is introduced using approximate lambda operators, and the exact solution of the transfer problem is obtained by combination with a perturbation technique. Model atmospheres with up to 100 atomic levels in non-LTE can be constructed, exceeding remarkably the capacities of the classical linearization approach as presented by Auer and Mihalas (1969). It is now possible to examine the effects of metal line blanketing in non-LTE stellar atmospheres, since many more sources of opacities may be included. The applicability of this method is demonstrated by calculating a small sample of pure-hydrogen atmospheres.

  3. Non-LTE equivalent widths for N II with error estimates

    NASA Astrophysics Data System (ADS)

    Ahmed, A.; Sigut, T. A. A.

    2016-01-01

    Non-local thermodynamic equilibrium (non-LTE) calculations are performed for N II in stellar atmospheric models appropriate to main-sequence B stars to produce new grids of equivalent widths for the strongest N II lines commonly used for abundance analysis. There is reasonable agreement between our calculations and previous results, although we find weaker non-LTE effects in the strongest optical N II transition, λ3995. We also present a detailed estimation of the uncertainties in the equivalent widths due to inaccuracies in the atomic data via Monte Carlo simulation and investigate the completeness of our model atom in terms of included energy levels. Uncertainties in the basic N II atomic data limit the accuracy of abundance determinations to ≈ ±0.10 dex at the peak of the N II optical spectrum near Teff ≈ 24 000 K.

  4. X-ray emission spectroscopy of well-characterised non-LTE plasmas

    NASA Astrophysics Data System (ADS)

    Bourgaux, A. C.; Bastiani-Ceccotti, S.; Audebert, P.; Marquès, J. R.; Vassura, L.; Vinci, T.; Dorchies, F.; Leguay, P. M.; Chung, H. K.; Bowen, C.; Dervieux, V.; Renaudin, P.; Silvert, V.; Jacquemot, S.

    2016-03-01

    This paper will present an experimental platform developed on LULI2000 to measure x-ray emission of non-LTE plasmas in well-defined hydrodynamic conditions thanks to implementation of a whole set of diagnostics, including time-resolved electronic and ionic Thomson scattering and self-optical pyrometry. K-, L- and M-shell spectra will be presented and the methodology, that has been developed to analyze them, discussed.

  5. A non-LTE retrieval scheme for sounding the upper atmosphere of Mars in the infrared

    NASA Astrophysics Data System (ADS)

    Lopez-Valverde, Miguel Angel; García-Comas, Maya; Funke, Bernd; Jimenez-Monferrer, Sergio; Lopez-Puertas, Manuel

    2016-04-01

    Several instruments on board Mars Express have been sounding the upper atmosphere of Mars systematically in a limb geometry in the IR part of the spectrum. Two of them in particular, OMEGA and PFS, performed emission measurements during daytime and detected the strongest IR bands of species like CO2 and CO (Piccialli et al, JGRE, submitted). Similarly on Venus, the instrument VIRTIS carried out observations of CO2 and CO bands at 2.7, 4.3 and 4.7 um at high altitudes (Gilli et al, JGRE, 2009). All these daylight atmospheric emissions respond to fluorescent situations, a case of non-local thermodynamic equilibrum conditions (non-LTE), well understood nowadays using comprehensive non-LTE theoretical models and tools (Lopez-Valverde et al., Planet. Space Sci., 2011). However, extensive exploitation of these emissions has only been done in optically thin conditions to date (Gilli et al, Icarus, 2015) or in a broad range of altitudes if in nadir geometry (Peralta et al, Apj, 2015). Within the H2020 project UPWARDS we aim at performing retrievals under non-LTE conditions including optically thick cases, like those of the CO2 and CO strongest bands during daytime in the upper atmosphere of Mars. Similar effort will also be applied eventually to Venus. We will present the non-LTE scheme used for such retrievals, based on similar efforts performed recently in studies of the Earth's upper atmosphere using data from the MIPAS instrument, on board Envisat (Funke et al., Atmos. Chem. Phys., 2009; Jurado-Navarro, PhD Thesis, Univ. Granada, 2015). Acknowledgemnt: This work is supported by the European Union's Horizon 2020 Programme under grant agreement UPWARDS-633127

  6. Departures from LTE for neutral Li in late-type stars

    NASA Astrophysics Data System (ADS)

    Lind, K.; Asplund, M.; Barklem, P. S.

    2009-08-01

    We perform non-LTE calculations of lithium in late-type stars for a wide range of stellar parameters, including quantum mechanical cross-sections for collisions with neutral hydrogen and the negative hydrogen ion. Non-LTE abundance corrections for the lithium resonance line at 670.7 nm and the subordinate line at 610.3 nm, are calculated using 1D MARCS model atmospheres spanning a grid T_eff = [4000, 8000] K, log g = [1.0, 5.0], and [Fe/H] = [0.0, -3.0], for lithium abundances in the range A(Li) = [-0.3, 4.2]. The competing effects of ultraviolet over-ionization and photon losses in the resonance line govern the behaviour of the non-LTE effects with stellar parameters and lithium abundance. The size and sign of the non-LTE abundance corrections vary significantly over the grid for the 670.7 nm line, but are typically positive and below 0.15 dex for the 610.3 nm, line. The new collisional data play a significant role in determining the abundance corrections. Complete Tables [see full textsee full textsee full textsee full textsee full text] and [see full textsee full textsee full textsee full textsee full text] are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/503/541

  7. Wideband LTE power amplifier with integrated novel analog pre-distorter linearizer for mobile wireless communications.

    PubMed

    Uthirajoo, Eswaran; Ramiah, Harikrishnan; Kanesan, Jeevan; Reza, Ahmed Wasif

    2014-01-01

    For the first time, a new circuit to extend the linear operation bandwidth of a LTE (Long Term Evolution) power amplifier, while delivering a high efficiency is implemented in less than 1 mm2 chip area. The 950 µm × 900 µm monolithic microwave integrated circuit (MMIC) power amplifier (PA) is fabricated in a 2 µm InGaP/GaAs process. An on-chip analog pre-distorter (APD) is designed to improve the linearity of the PA, up to 20 MHz channel bandwidth. Intended for 1.95 GHz Band 1 LTE application, the PA satisfies adjacent channel leakage ratio (ACLR) and error vector magnitude (EVM) specifications for a wide LTE channel bandwidth of 20 MHz at a linear output power of 28 dBm with corresponding power added efficiency (PAE) of 52.3%. With a respective input and output return loss of 30 dB and 14 dB, the PA's power gain is measured to be 32.5 dB while exhibiting an unconditional stability characteristic from DC up to 5 GHz. The proposed APD technique serves to be a good solution to improve linearity of a PA without sacrificing other critical performance metrics. PMID:25033049

  8. Multi-Group Reductions of LTE Air Plasma Radiative Transfer in Cylindrical Geometries

    NASA Technical Reports Server (NTRS)

    Scoggins, James; Magin, Thierry Edouard Bertran; Wray, Alan; Mansour, Nagi N.

    2013-01-01

    Air plasma radiation in Local Thermodynamic Equilibrium (LTE) within cylindrical geometries is studied with an application towards modeling the radiative transfer inside arc-constrictors, a central component of constricted-arc arc jets. A detailed database of spectral absorption coefficients for LTE air is formulated using the NEQAIR code developed at NASA Ames Research Center. The database stores calculated absorption coefficients for 1,051,755 wavelengths between 0.04 µm and 200 µm over a wide temperature (500K to 15 000K) and pressure (0.1 atm to 10.0 atm) range. The multi-group method for spectral reduction is studied by generating a range of reductions including pure binning and banding reductions from the detailed absorption coefficient database. The accuracy of each reduction is compared to line-by-line calculations for cylindrical temperature profiles resembling typical profiles found in arc-constrictors. It is found that a reduction of only 1000 groups is sufficient to accurately model the LTE air radiation over a large temperature and pressure range. In addition to the reduction comparison, the cylindrical-slab formulation is compared with the finite-volume method for the numerical integration of the radiative flux inside cylinders with varying length. It is determined that cylindrical-slabs can be used to accurately model most arc-constrictors due to their high length to radius ratios.

  9. Non-LTE modeling for the National Ignition Facility (and beyond)

    NASA Astrophysics Data System (ADS)

    Scott, H. A.; Hammel, B. A.; Hansen, S. B.

    2012-05-01

    Considerable progress has been made in the last year in the study of laser-driven inertial confinement fusion at the National Ignition Facility (NIF). Experiments have demonstrated symmetric capsule implosions with plasma conditions approaching those required for ignition. Improvements in computational models - in large part due to advances in non-LTE modeling - have resulted in simulations that match experimental results quite well for the X-ray drive, implosion symmetry and total wall emission [1]. Non-LTE modeling is a key part of the NIF simulation effort, affecting several aspects of experimental design and diagnostics. The X-rays that drive the capsule arise from high-Z material ablated off the hohlraum wall. Current capsule designs avoid excessive preheat from high-energy X-rays by shielding the fuel with a mid-Z dopant, which affects the capsule dynamics. The dopant also mixes into the hot spot through hydrodynamic instabilities, providing diagnostic possibilities but potentially impacting the energy balance of the capsule [2]. Looking beyond the NIF, a proposed design for a fusion reactor chamber depends on lowdensity high-Z gas absorbing X-rays and particles to protect the first wall [3]. These situations encompass a large range of temperatures, densities and spatial scales. They each emphasize different aspects of atomic physics and present a variety of challenges for non-LTE modeling. We discuss the relevant issues and summarize the current state of the modeling effort for these applications.

  10. Investigation of a new handover approach in LTE and WiMAX.

    PubMed

    Hindia, Mohammad Nour; Reza, Ahmed Wasif; Noordin, Kamarul Ariffin

    2014-01-01

    Nowadays, one of the most important challenges in heterogeneous networks is the connection consistency between the mobile station and the base stations. Furthermore, along the roaming process between the mobile station and the base station, the system performance degrades significantly due to the interferences from neighboring base stations, handovers to inaccurate base station and inappropriate technology selection. In this paper, several algorithms are proposed to improve mobile station performance and seamless mobility across the long-term evolution (LTE) and Worldwide Interoperability for Microwave Access (WiMAX) technologies, along with a minimum number of redundant handovers. Firstly, the enhanced global positioning system (GPS) and the novel received signal strength (RSS) prediction approaches are suggested to predict the target base station accurately. Then, the multiple criteria with two thresholds algorithm is proposed to prioritize the selection between LTE and WiMAX as the target technology. In addition, this study also covers the intercell and cochannel interference reduction by adjusting the frequency reuse ratio 3 (FRR3) to work with LTE and WiMAX. The obtained results demonstrate high next base station prediction efficiency and high accuracy for both horizontal and vertical handovers. Moreover, the received signal strength is kept at levels higher than the threshold, while maintaining low connection cost and delay within acceptable levels. In order to highlight the combination of the proposed algorithms' performance, it is compared with the existing RSS and multiple criteria handover decision algorithms. PMID:25379524

  11. Wideband LTE Power Amplifier with Integrated Novel Analog Pre-Distorter Linearizer for Mobile Wireless Communications

    PubMed Central

    Uthirajoo, Eswaran; Ramiah, Harikrishnan; Kanesan, Jeevan; Reza, Ahmed Wasif

    2014-01-01

    For the first time, a new circuit to extend the linear operation bandwidth of a LTE (Long Term Evolution) power amplifier, while delivering a high efficiency is implemented in less than 1 mm2 chip area. The 950 µm × 900 µm monolithic microwave integrated circuit (MMIC) power amplifier (PA) is fabricated in a 2 µm InGaP/GaAs process. An on-chip analog pre-distorter (APD) is designed to improve the linearity of the PA, up to 20 MHz channel bandwidth. Intended for 1.95 GHz Band 1 LTE application, the PA satisfies adjacent channel leakage ratio (ACLR) and error vector magnitude (EVM) specifications for a wide LTE channel bandwidth of 20 MHz at a linear output power of 28 dBm with corresponding power added efficiency (PAE) of 52.3%. With a respective input and output return loss of 30 dB and 14 dB, the PA’s power gain is measured to be 32.5 dB while exhibiting an unconditional stability characteristic from DC up to 5 GHz. The proposed APD technique serves to be a good solution to improve linearity of a PA without sacrificing other critical performance metrics. PMID:25033049

  12. Investigation of a New Handover Approach in LTE and WiMAX

    PubMed Central

    Hindia, Mohammad Nour; Reza, Ahmed Wasif; Noordin, Kamarul Ariffin

    2014-01-01

    Nowadays, one of the most important challenges in heterogeneous networks is the connection consistency between the mobile station and the base stations. Furthermore, along the roaming process between the mobile station and the base station, the system performance degrades significantly due to the interferences from neighboring base stations, handovers to inaccurate base station and inappropriate technology selection. In this paper, several algorithms are proposed to improve mobile station performance and seamless mobility across the long-term evolution (LTE) and Worldwide Interoperability for Microwave Access (WiMAX) technologies, along with a minimum number of redundant handovers. Firstly, the enhanced global positioning system (GPS) and the novel received signal strength (RSS) prediction approaches are suggested to predict the target base station accurately. Then, the multiple criteria with two thresholds algorithm is proposed to prioritize the selection between LTE and WiMAX as the target technology. In addition, this study also covers the intercell and cochannel interference reduction by adjusting the frequency reuse ratio 3 (FRR3) to work with LTE and WiMAX. The obtained results demonstrate high next base station prediction efficiency and high accuracy for both horizontal and vertical handovers. Moreover, the received signal strength is kept at levels higher than the threshold, while maintaining low connection cost and delay within acceptable levels. In order to highlight the combination of the proposed algorithms' performance, it is compared with the existing RSS and multiple criteria handover decision algorithms. PMID:25379524

  13. Optimized Scheduling Technique of Null Subcarriers for Peak Power Control in 3GPP LTE Downlink

    PubMed Central

    Park, Sang Kyu

    2014-01-01

    Orthogonal frequency division multiple access (OFDMA) is a key multiple access technique for the long term evolution (LTE) downlink. However, high peak-to-average power ratio (PAPR) can cause the degradation of power efficiency. The well-known PAPR reduction technique, dummy sequence insertion (DSI), can be a realistic solution because of its structural simplicity. However, the large usage of subcarriers for the dummy sequences may decrease the transmitted data rate in the DSI scheme. In this paper, a novel DSI scheme is applied to the LTE system. Firstly, we obtain the null subcarriers in single-input single-output (SISO) and multiple-input multiple-output (MIMO) systems, respectively; then, optimized dummy sequences are inserted into the obtained null subcarrier. Simulation results show that Walsh-Hadamard transform (WHT) sequence is the best for the dummy sequence and the ratio of 16 to 20 for the WHT and randomly generated sequences has the maximum PAPR reduction performance. The number of near optimal iteration is derived to prevent exhausted iterations. It is also shown that there is no bit error rate (BER) degradation with the proposed technique in LTE downlink system. PMID:24883376

  14. Physics of Solar Prominences: I—Spectral Diagnostics and Non-LTE Modelling

    NASA Astrophysics Data System (ADS)

    Labrosse, N.; Heinzel, P.; Vial, J.-C.; Kucera, T.; Parenti, S.; Gunár, S.; Schmieder, B.; Kilper, G.

    2010-04-01

    This review paper outlines background information and covers recent advances made via the analysis of spectra and images of prominence plasma and the increased sophistication of non-LTE ( i.e. when there is a departure from Local Thermodynamic Equilibrium) radiative transfer models. We first describe the spectral inversion techniques that have been used to infer the plasma parameters important for the general properties of the prominence plasma in both its cool core and the hotter prominence-corona transition region. We also review studies devoted to the observation of bulk motions of the prominence plasma and to the determination of prominence mass. However, a simple inversion of spectroscopic data usually fails when the lines become optically thick at certain wavelengths. Therefore, complex non-LTE models become necessary. We thus present the basics of non-LTE radiative transfer theory and the associated multi-level radiative transfer problems. The main results of one- and two-dimensional models of the prominences and their fine-structures are presented. We then discuss the energy balance in various prominence models. Finally, we outline the outstanding observational and theoretical questions, and the directions for future progress in our understanding of solar prominences.

  15. A Multiuser Manufacturing Resource Service Composition Method Based on the Bees Algorithm.

    PubMed

    Xie, Yongquan; Zhou, Zude; Pham, Duc Truong; Xu, Wenjun; Ji, Chunqian

    2015-01-01

    In order to realize an optimal resource service allocation in current open and service-oriented manufacturing model, multiuser resource service composition (RSC) is modeled as a combinational and constrained multiobjective problem. The model takes into account both subjective and objective quality of service (QoS) properties as representatives to evaluate a solution. The QoS properties aggregation and evaluation techniques are based on existing researches. The basic Bees Algorithm is tailored for finding a near optimal solution to the model, since the basic version is only proposed to find a desired solution in continuous domain and thus not suitable for solving the problem modeled in our study. Particular rules are designed for handling the constraints and finding Pareto optimality. In addition, the established model introduces a trusted service set to each user so that the algorithm could start by searching in the neighbor of more reliable service chains (known as seeds) than those randomly generated. The advantages of these techniques are validated by experiments in terms of success rate, searching speed, ability of avoiding ingenuity, and so forth. The results demonstrate the effectiveness of the proposed method in handling multiuser RSC problems. PMID:26339232

  16. Medium Access in Spread-Spectrum Ad Hoc Networks with Multiuser Detection

    NASA Astrophysics Data System (ADS)

    Kusume, Katsutoshi; Vilzmann, Robert; Müller, Andreas; Hartmann, Christian; Bauch, Gerhard

    2008-12-01

    Conventional medium access control protocols are designed to avoid simultaneous transmissions, based on a simple collision model in the underlying physical layer. Recently, strong physical layer capabilities, enabled by multiuser detection techniques, have been studied in connection with simple medium access control protocols, for example, slotted ALOHA. We think that neither of these extreme approaches is optimum, particularly in general scenarios where network nodes with different signal processing capabilities coexist. Instead of dealing with interferences in either of the two layers alone, both medium access control and physical layer functionalities should be designed to cooperate and complement each other. We discuss several key aspects for designing such a protocol, especially with an emphasis on iterative multiuser detection, which can provide a good tradeoff between performance and complexity. We propose a new protocol called MUD-MAC which satisfies these key aspects. We analyze its throughput bound and also perform numerical simulations. The simulation results show excellent throughput improvements. It is also demonstrated that the MUD-MAC protocol provides certain fairness among network nodes with different signal processing capabilities.

  17. Advancing MEMS Technology Usage through the MUMPS (Multi-User MEMS Processes) Program

    NASA Technical Reports Server (NTRS)

    Koester, D. A.; Markus, K. W.; Dhuler, V.; Mahadevan, R.; Cowen, A.

    1995-01-01

    In order to help provide access to advanced micro-electro-mechanical systems (MEMS) technologies and lower the barriers for both industry and academia, the Microelectronic Center of North Carolina (MCNC) and ARPA have developed a program which provides users with access to both MEMS processes and advanced electronic integration techniques. The four distinct aspects of this program, the multi-user MEMS processes (MUMP's), the consolidated micro-mechanical element library, smart MEMS, and the MEMS technology network are described in this paper. MUMP's is an ARPA-supported program created to provide inexpensive access to MEMS technology in a multi-user environment. It is both a proof-of-concept and educational tool that aids in the development of MEMS in the domestic community. MUMP's technologies currently include a 3-layer poly-silicon surface micromachining process and LIGA (lithography, electroforming, and injection molding) processes that provide reasonable design flexibility within set guidelines. The consolidated micromechanical element library (CaMEL) is a library of active and passive MEMS structures that can be downloaded by the MEMS community via the internet. Smart MEMS is the development of advanced electronics integration techniques for MEMS through the application of flip chip technology. The MEMS technology network (TechNet) is a menu of standard substrates and MEMS fabrication processes that can be purchased and combined to create unique process flows. TechNet provides the MEMS community greater flexibility and enhanced technology accessibility.

  18. A Multiuser Manufacturing Resource Service Composition Method Based on the Bees Algorithm

    PubMed Central

    Xie, Yongquan; Zhou, Zude; Pham, Duc Truong; Xu, Wenjun; Ji, Chunqian

    2015-01-01

    In order to realize an optimal resource service allocation in current open and service-oriented manufacturing model, multiuser resource service composition (RSC) is modeled as a combinational and constrained multiobjective problem. The model takes into account both subjective and objective quality of service (QoS) properties as representatives to evaluate a solution. The QoS properties aggregation and evaluation techniques are based on existing researches. The basic Bees Algorithm is tailored for finding a near optimal solution to the model, since the basic version is only proposed to find a desired solution in continuous domain and thus not suitable for solving the problem modeled in our study. Particular rules are designed for handling the constraints and finding Pareto optimality. In addition, the established model introduces a trusted service set to each user so that the algorithm could start by searching in the neighbor of more reliable service chains (known as seeds) than those randomly generated. The advantages of these techniques are validated by experiments in terms of success rate, searching speed, ability of avoiding ingenuity, and so forth. The results demonstrate the effectiveness of the proposed method in handling multiuser RSC problems. PMID:26339232

  19. The Fluids and Combustion Facility Combustion Integrated Rack and The Multi-User Droplet Combustion Apparatus: Microgravity Combustion Science Using A Modular Multi-User Hardware

    NASA Astrophysics Data System (ADS)

    O'Malley, T. F.; Myhre, C. A.

    2002-01-01

    The Fluids and Combustion Facility (FCF) is a multi-rack payload planned for the International Space Station that will enable the study of fluid physics and combustion science in a microgravity environment. The Combustion Integrated Rack (CIR) is one of two International Standard Payload Racks of the FCF and is being designed primarily to support combustion science experiments. It is currently in the Flight Unit Build phase. The Multi-user Droplet Combustion Apparatus (MDCA) is a multi-user facility designed to accommodate four different droplet combustion science experiments and is the first payload for CIR. MDCA is currently in the Engineering Model build phase. Launch of the CIR and MDCA is planned for 2004. The CIR will function independently until the later launch of the Fluids Integrated Rack component of the FCF. This paper provides an overview of the capabilities and the development status of the CIR and MDCA. The CIR will contain the hardware and software required to support combustion experiments in space. It will contain an optics bench, combustion chamber, fuel oxidizer and management assembly, exhaust vent system, diagnostic cameras, power, environment control system, command and data management system, and a passive rack isolation system. Additional hardware will be installed in the chamber and on the optics bench that is customized for each science investigation. The chamber insert may provide the sample holder, small ignition source, and small diagnostics such as thermocouples and radiometers. The combustion experiments that may be conducted in the FCF include, but are not limited to, the study of laminar flames, reaction kinetics, droplet and spray combustion, flame spread, fire and fire suppressants, condensed phase organic fuel combustion, turbulent combustion, soot and polycyclic aromatic hydrocarbons, and materials synthesis. It is expected that the facility will provide most of the hardware, with a small amount of unique hardware developed for

  20. Applications of the Helping Relationship in Multi-User Virtual Environments: An Exploration of Counseling from Practitioners' Perspectives

    ERIC Educational Resources Information Center

    Witt, Karl Jerome

    2011-01-01

    This study explores the perceptions of professional counselors who provide avatar-based services in multi-user virtual environments (MUVEs) and their descriptions of those services. Using a virtual micro-ethnographic design, the principal investigator interviewed counselors (N=5) licensed or certified to practice in their geographic location about…

  1. Multi-use botanochemical crops, an economic analysis and feasibility study

    SciTech Connect

    Buchanan, R.; Otey, F.H.; Hamerstrand, G.E.

    1980-12-01

    Dwindling reserves and increasing costs of petroleum have brought the realization that agricultural production of substitutes may be both feasible and the best long-term alternative. Multi-use oil- and hydrocarbon-producing (botanochemical) crops, specially designed for an adaptive agricultural system, appear to offer potential for combining the production of both food and industrial raw materials with increased overall productivity. Processing methods are being developed for extraction of primary botanochemicals, i.e,. soluble polyphenols, whole-plant oils, and isoprene polymers that could serve as chemical feedstocks. The extractive-free residues are promising raw materials for papermaking fibers, animal feeds, fermentation substrates, chemical feedstocks, fuels, and soil amendments. Preliminary cost assessments of crop production, collection, and processing compared with projected produce values suggest that a new and radically different agricultural system would be economically attractive.

  2. Multi-use botanonchemical crops, an economic analysis and feasibility study

    NASA Astrophysics Data System (ADS)

    Buchanan, A. R.; Otey, F. H.; Hamerstrand, G. E.

    1980-12-01

    Dwindling reserves and increasing costs of petroleum have brought the realization that agricultural production of substitutes may be both feasible and the best long-term alternative. Multi-use oil- and hydrocarbon-producing (botanochemical) crops, specially designed for an adaptive agricultural system, appear to offer potential for combining the production of both food and industrial raw materials with increased overall productivity. Processing methods are being developed for extraction of primary botanochemicals, i.e,. soluble polyphenols, whole-plant oils, and isoprene polymers that could serve as chemical feedstocks. The extractive-free residues are promising raw materials for papermaking fibers, animal feeds, fermentation substrates, chemical feedstocks, fuels, and soil amendments. Preliminary cost assessments of crop production, collection, and processing compared with projected produce values suggest that a new and radically different agricultural system would be economically attractive.

  3. Interaction Design and Usability of Learning Spaces in 3D Multi-user Virtual Worlds

    NASA Astrophysics Data System (ADS)

    Minocha, Shailey; Reeves, Ahmad John

    Three-dimensional virtual worlds are multimedia, simulated environments, often managed over the Web, which users can 'inhabit' and interact via their own graphical, self-representations known as 'avatars'. 3D virtual worlds are being used in many applications: education/training, gaming, social networking, marketing and commerce. Second Life is the most widely used 3D virtual world in education. However, problems associated with usability, navigation and way finding in 3D virtual worlds may impact on student learning and engagement. Based on empirical investigations of learning spaces in Second Life, this paper presents design guidelines to improve the usability and ease of navigation in 3D spaces. Methods of data collection include semi-structured interviews with Second Life students, educators and designers. The findings have revealed that design principles from the fields of urban planning, Human- Computer Interaction, Web usability, geography and psychology can influence the design of spaces in 3D multi-user virtual environments.

  4. Investigation of improved designs for rotational micromirrors using multiuser MEMS processes

    NASA Astrophysics Data System (ADS)

    Lin, Julianna E.; Michael, Feras S. J.; Kirk, Andrew G.

    2001-04-01

    In recent years, the design of rotational micromirrors for use in optical cross connects has received much attention. Although several companies have already produced and marketed a number of torsional mirror devices, more work is still needed to determine how these mirrors can be integrated into optical systems to form compact optical switches. However, recently several commercial MEMS foundry services have become available. Thus, due to the low cost of these prototyping services, new devices can be fabricated in short amounts of time and the designs adapted to meet the needs of different applications. The purpose of this work is to investigate the fabrication of new micromirror designs using the Multi-User MEMS Processes (MUMPs) foundry service available from Cronos Integrated Microsystems, located in North Carolina, USA). Several sets of mirror designs were submitted for fabrication and the resulting structures characterized using a phase-shifting Mirau interferometer. The results of these devices are presented.

  5. FBMC receiver for multi-user asynchronous transmission on fragmented spectrum

    NASA Astrophysics Data System (ADS)

    Doré, Jean-Baptiste; Berg, Vincent; Cassiau, Nicolas; Kténas, Dimitri

    2014-12-01

    Relaxed synchronization and access to fragmented spectrum are considered for future generations of wireless networks. Frequency division multiple access for filter bank multicarrier (FBMC) modulation provides promising performance without strict synchronization requirements contrary to conventional orthogonal frequency division multiplexing (OFDM). The architecture of a FBMC receiver suitable for this scenario is considered. Carrier frequency offset (CFO) compensation is combined with intercarrier interference (ICI) cancellation and performs well under very large frequency offsets. Channel estimation and interpolation had to be adapted and proved effective even for heavily fragmented spectrum usage. Channel equalization can sustain large delay spread. Because all the receiver baseband signal processing functionalities are proposed in the frequency domain, the overall architecture is suitable for multiuser asynchronous transmission on fragmented spectrum.

  6. A game-theoretical pricing mechanism for multiuser rate allocation for video over WiMAX

    NASA Astrophysics Data System (ADS)

    Chen, Chao-An; Lo, Chi-Wen; Lin, Chia-Wen; Chen, Yung-Chang

    2010-07-01

    In multiuser rate allocation in a wireless network, strategic users can bias the rate allocation by misrepresenting their bandwidth demands to a base station, leading to an unfair allocation. Game-theoretical approaches have been proposed to address the unfair allocation problems caused by the strategic users. However, existing approaches rely on a timeconsuming iterative negotiation process. Besides, they cannot completely prevent unfair allocations caused by inconsistent strategic behaviors. To address these problems, we propose a Search Based Pricing Mechanism to reduce the communication time and to capture a user's strategic behavior. Our simulation results show that the proposed method significantly reduce the communication time as well as converges stably to an optimal allocation.

  7. Blind multiuser detector for chaos-based CDMA using support vector machine.

    PubMed

    Kao, Johnny Wei-Hsun; Berber, Stevan Mirko; Kecman, Vojislav

    2010-08-01

    The algorithm and the results of a blind multiuser detector using a machine learning technique called support vector machine (SVM) on a chaos-based code division multiple access system is presented in this paper. Simulation results showed that the performance achieved by using SVM is comparable to existing minimum mean square error (MMSE) detector under both additive white Gaussian noise (AWGN) and Rayleigh fading conditions. However, unlike the MMSE detector, the SVM detector does not require the knowledge of spreading codes of other users in the system or the estimate of the channel noise variance. The optimization of this algorithm is considered in this paper and its complexity is compared with the MMSE detector. This detector is much more suitable to work in the forward link than MMSE. In addition, original theoretical bit-error rate expressions for the SVM detector under both AWGN and Rayleigh fading are derived to verify the simulation results. PMID:20570769

  8. Comparison of two underwater acoustic communications techniques for multi-user access

    NASA Astrophysics Data System (ADS)

    Hursky, Paul; Siderius, T. Martin; Kauaiex Group

    2001-05-01

    Frequency hopped frequency shift keying (FHFSK) and code division multiple access (CDMA) are two different modulation techniques for multiple users to communicate with a single receiver simultaneously. In July 2003, these two techniques were tested alongside each other in a shallow water coastal environment off the coast of Kauai. A variety of instruments were used to measure the prevailing oceanography, enabling detailed modeling of the channel. The channel was acoustically probed using LFM waveforms and m-sequences as well. We will present the results of demodulating the FHFSK and CDMA waveforms and discuss modeling the channel for the purpose of predicting multi-user communications performance. a)Michael B. Porter, Paul Hursky, Martin Siderius (SAIC), Mohsen Badiey (UD), Jerald Caruthers (USM), William S. Hodgkiss, Kaustubha Raghukumar (SIO), Dan Rouseff, Warren Fox (APL-UW), Christian de Moustier, Brian Calder, Barbara J. Kraft (UNH), Keyko McDonald (SPAWARSSC), Peter Stein, James K. Lewis, and Subramaniam Rajan (SSI).

  9. A joint swarm intelligence algorithm for multi-user detection in MIMO-OFDM system

    NASA Astrophysics Data System (ADS)

    Hu, Fengye; Du, Dakun; Zhang, Peng; Wang, Zhijun

    2014-11-01

    In the multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) system, traditional multi-user detection (MUD) algorithms that usually used to suppress multiple access interference are difficult to balance system detection performance and the complexity of the algorithm. To solve this problem, this paper proposes a joint swarm intelligence algorithm called Ant Colony and Particle Swarm Optimisation (AC-PSO) by integrating particle swarm optimisation (PSO) and ant colony optimisation (ACO) algorithms. According to simulation results, it has been shown that, with low computational complexity, the MUD for the MIMO-OFDM system based on AC-PSO algorithm gains comparable MUD performance with maximum likelihood algorithm. Thus, the proposed AC-PSO algorithm provides a satisfactory trade-off between computational complexity and detection performance.

  10. Validation of a Pre-Coded Food Diary Used among 60–80 Year Old Men: Comparison of Self-Reported Energy Intake with Objectively Recorded Energy Expenditure

    PubMed Central

    Stea, Tonje H.; Andersen, Lene F.; Paulsen, Gøran; Hetlelid, Ken J.; Lohne-Seiler, Hilde; Ådnanes, Svanhild; Bjørnsen, Thomas; Salvesen, Svein; Berntsen, Sveinung

    2014-01-01

    Objective To validate energy intake (EI) estimated from a pre-coded food diary (PFD) against energy expenditure (EE) measured with a valid physical activity monitor (SenseWear Pro3 Armband) and to evaluate whether misreporting was associated with overweight/obesity in a group of elderly men. Methods Forty-seven healthy Norwegian men, 60–80 years old, completed the study. As this study was part of a larger intervention study, cross-sectional data were collected at both baseline and post-test. Participants recorded their food intake for four consecutive days using food diaries and wore SenseWear Pro3 Armband (SWA) during the same period. Only participants with complete data sets at both baseline and post-test were included in the study. Results The group average EI was 17% lower at baseline and 18% lower at post-test compared to measured EE. Mean difference from Bland-Altman plot for EI and EE was −1.5 MJ/day (±1.96 SD: −7.0, 4.0 MJ/day) at baseline and −1.6 MJ/day (−6.6, 3.4 MJ/day) at post-test. The intraclass correlation coefficient (ICC) was 0.30 (95% CI: 0.02, 0.54, p = 0.018) at baseline and 0.34 (0.06, 0.57, p = 0.009) at post-test. Higher values of underreporting was shown among overweight/obese compared to normal weight participants at both baseline and post-test (p≤ 0.001), respectively. Conclusions The results indicate that the PFD could be a useful tool for estimating energy intake in normal weight elderly men. On the other hand, the PFD seems to be less suitable for estimating energy intake in overweight/obese elderly men. PMID:25019949

  11. An investigation of interference coordination in heterogeneous network for LTE-Advanced systems

    NASA Astrophysics Data System (ADS)

    Hasan, M. K.; Ismail, A. F.; H, Aisha-Hassan A.; Abdullah, Khaizuran; Ramli, H. A. M.

    2013-12-01

    The novel "femtocell" in Heterogeneous Network (HetNet) for LTE-Advanced (LTE-A) set-up will allow Malaysian wireless telecommunication operators (Maxis, Celcom, Digi, U-Mobile, P1, YTL and etc2.) to extend connectivity coverage where access would otherwise be limited or unavailable, particularly indoors of large building complexes. A femtocell is a small-sized cellular base station that encompasses all the functionality of a typical station. It therefore allows a simpler and self-contained deployment including private residences. For the Malaysian service providers, the main attractions of femtocell usage are the improvements to both coverage and capacity. The operators can provide a better service to end-users in turn reduce much of the agitations and complaints. There will be opportunity for new services at reduced cost. In addition, the operator not only benefits from the improved capacity and coverage but also can reduce both capital expenditure and operating expense i.e. alternative to brand new base station or macrocell installation. Interference is a key issue associated with femtocell development. There are a large number of issues associated with interference all of which need to be investigated, identified, quantified and solved. This is to ensure that the deployment of any femtocells will take place successfully. Among the most critical challenges in femtocell deployment is the interference between femtocell-to-macrocell and femtocell-to-femtocell in HetNets. In this paper, all proposed methods and algorithms will be investigated in the OFDMA femtocell system considering HetNet scenarios for LTE-A.

  12. Base Station Placement Algorithm for Large-Scale LTE Heterogeneous Networks

    PubMed Central

    Lee, Seungseob; Lee, SuKyoung; Kim, Kyungsoo; Kim, Yoon Hyuk

    2015-01-01

    Data traffic demands in cellular networks today are increasing at an exponential rate, giving rise to the development of heterogeneous networks (HetNets), in which small cells complement traditional macro cells by extending coverage to indoor areas. However, the deployment of small cells as parts of HetNets creates a key challenge for operators’ careful network planning. In particular, massive and unplanned deployment of base stations can cause high interference, resulting in highly degrading network performance. Although different mathematical modeling and optimization methods have been used to approach various problems related to this issue, most traditional network planning models are ill-equipped to deal with HetNet-specific characteristics due to their focus on classical cellular network designs. Furthermore, increased wireless data demands have driven mobile operators to roll out large-scale networks of small long term evolution (LTE) cells. Therefore, in this paper, we aim to derive an optimum network planning algorithm for large-scale LTE HetNets. Recently, attempts have been made to apply evolutionary algorithms (EAs) to the field of radio network planning, since they are characterized as global optimization methods. Yet, EA performance often deteriorates rapidly with the growth of search space dimensionality. To overcome this limitation when designing optimum network deployments for large-scale LTE HetNets, we attempt to decompose the problem and tackle its subcomponents individually. Particularly noting that some HetNet cells have strong correlations due to inter-cell interference, we propose a correlation grouping approach in which cells are grouped together according to their mutual interference. Both the simulation and analytical results indicate that the proposed solution outperforms the random-grouping based EA as well as an EA that detects interacting variables by monitoring the changes in the objective function algorithm in terms of system

  13. Base Station Placement Algorithm for Large-Scale LTE Heterogeneous Networks.

    PubMed

    Lee, Seungseob; Lee, SuKyoung; Kim, Kyungsoo; Kim, Yoon Hyuk

    2015-01-01

    Data traffic demands in cellular networks today are increasing at an exponential rate, giving rise to the development of heterogeneous networks (HetNets), in which small cells complement traditional macro cells by extending coverage to indoor areas. However, the deployment of small cells as parts of HetNets creates a key challenge for operators' careful network planning. In particular, massive and unplanned deployment of base stations can cause high interference, resulting in highly degrading network performance. Although different mathematical modeling and optimization methods have been used to approach various problems related to this issue, most traditional network planning models are ill-equipped to deal with HetNet-specific characteristics due to their focus on classical cellular network designs. Furthermore, increased wireless data demands have driven mobile operators to roll out large-scale networks of small long term evolution (LTE) cells. Therefore, in this paper, we aim to derive an optimum network planning algorithm for large-scale LTE HetNets. Recently, attempts have been made to apply evolutionary algorithms (EAs) to the field of radio network planning, since they are characterized as global optimization methods. Yet, EA performance often deteriorates rapidly with the growth of search space dimensionality. To overcome this limitation when designing optimum network deployments for large-scale LTE HetNets, we attempt to decompose the problem and tackle its subcomponents individually. Particularly noting that some HetNet cells have strong correlations due to inter-cell interference, we propose a correlation grouping approach in which cells are grouped together according to their mutual interference. Both the simulation and analytical results indicate that the proposed solution outperforms the random-grouping based EA as well as an EA that detects interacting variables by monitoring the changes in the objective function algorithm in terms of system

  14. Resource Allocation and Power Management Schemes in an LTE-Advanced Femtocell Network

    NASA Astrophysics Data System (ADS)

    Lee, Byung-Bog; Yu, Jae-Hak; Lee, In-Hwan; Pyo, Cheol-Sig; Kim, Se-Jin

    In this letter, we introduce two different resource allocation and Tx power management schemes, called resource control and fixed power (RCFP) and fixed resource and power control (FRPC), in an LTE-Advanced femtocell network. We analyze and compare the two schemes in terms of the system throughput for downlink and energy consumption of home evolved NodeB (HeNB) Tx power according to the number of HeNBs and home user equipment (HUE)'s user traffic density (C). The simulation results show that the FRPC scheme has better performance in terms of system throughput for macro user equipments (MUEs) and energy consumption in low C.

  15. An effective calculation method in theory of non-LTE stellar atmospheres - linearization separation technique.

    NASA Astrophysics Data System (ADS)

    Wu, G. Q.; Huang, R. Q.

    1994-06-01

    This paper introduces a new calculation method of non-LTE stellar atmospheres. This method is based on the combination of the advantages of the complete linearization method by Auer and Mihalas (1969) and the separated-iteration technique. First, the equation of radiative transfer and constraints are linearized respectively, then the linearized equation of the radiative transfer and the linearized constraints are solved, separately. It overcomes the disadvantages of requiring the simultaneous solution of the corresponding equations by the complete linearization. The applicability of this method by calculating a small sample of H-He atmospheres and H line formations is demonstrated.

  16. Non-LTE modeling of the structure and spectra of hot accretion spots on the surface of young stars

    NASA Astrophysics Data System (ADS)

    Dodin, A. V.

    2015-05-01

    The results of modeling the structure and spectra of hot accretion spots on the surface of young stars with allowance made for the departures from LTE for hydrogen and helium are presented. The existence of ram pressure of the infalling gas at the outer boundary of the hot spot has been found to lead to Stark broadening of the hydrogen line profiles to ˜1000 km s-1 at the accretion parameters considered. It is shown that allowance for the departures from LTE for carbon and oxygen atoms and ions does not lead to noticeable changes in the structure of the hot spot.

  17. Acoustic waves in the solar atmosphere. VII - Non-grey, non-LTE H(-) models

    NASA Technical Reports Server (NTRS)

    Schmitz, F.; Ulmschneider, P.; Kalkofen, W.

    1985-01-01

    The propagation and shock formation of radiatively damped acoustic waves in the solar chromosphere are studied under the assumption that H(-) is the only absorber; the opacity is non-grey. Deviations from local thermodynamic equilibrium (LTE) are permitted. The results of numerical simulations show the depth dependence of the heating by the acoustic waves to be insensitive to the mean state of the atmosphere. After the waves have developed into shocks, their energy flux decays exponentially with a constant damping length of about 1.4 times the pressure scale height, independent of initial flux and wave period. Departures from LTE have a strong influence on the mean temperature structure in dynamical chromosphere models; this is even more pronounced in models with reduced particle density - simulating conditions in magnetic flux tubes - which show significantly increased temperatures in response to mechanical heating. When the energy dissipation of the waves is sufficiently large to dissociate most of the H(-) ions, a strong temperature rise is found that is reminiscent of the temperature structure in the transition zone between chromosphere and corona; the energy flux remaining in the waves then drives mass motions.

  18. System-level performance of LTE-Advanced with joint transmission and dynamic point selection schemes

    NASA Astrophysics Data System (ADS)

    Määttänen, Helka-Liina; Hämäläinen, Kari; Venäläinen, Juha; Schober, Karol; Enescu, Mihai; Valkama, Mikko

    2012-12-01

    In this article, we present a practical coordinated multipoint (CoMP) system for LTE-Advanced. In this CoMP system, cooperation is enabled for cell-edge users via dynamic switching between the normal single-cell operation and CoMP. We first formulate a general CoMP system model of several CoMP schemes. We then investigate a practical finite-rate feedback design that simultaneously supports interference coordination, joint transmission (JT), and dynamic point selection (DPS) with a varying number of cooperating transmission points while operating a single-cell transmission as a fallback mode. We provide both link-level and system-level results for the evaluation of different feedback options for general CoMP operation. The results show that there are substantial performance gains in cell-edge throughputs for both JT and DPS CoMP over the baseline Release 10 LTE-Advanced with practical feedback options. We also show that CoMP can enable improved mobility management in real networks.

  19. Oxygen spectral line synthesis: 3D non-LTE with CO5BOLD hydrodynamical model atmospheres.

    NASA Astrophysics Data System (ADS)

    Prakapavičius, D.; Steffen, M.; Kučinskas, A.; Ludwig, H.-G.; Freytag, B.; Caffau, E.; Cayrel, R.

    In this work we present first results of our current project aimed at combining the 3D hydrodynamical stellar atmosphere approach with non-LTE (NLTE) spectral line synthesis for a number of key chemical species. We carried out a full 3D-NLTE spectrum synthesis of the oxygen IR 777 nm triplet, using a modified and improved version of our NLTE3D package to calculate departure coefficients for the atomic levels of oxygen in a CO5BOLD 3D hydrodynamical solar model atmosphere. Spectral line synthesis was subsequently performed with the Linfor3D code. In agreement with previous studies, we find that the lines of the oxygen triplet produce deeper cores under NLTE conditions, due to the diminished line source function in the line forming region. This means that the solar oxygen IR 777 nm lines should be stronger in NLTE, leading to negative 3D NLTE-LTE abundance corrections. Qualitatively this result would support previous claims for a relatively low solar oxygen abundance. Finally, we outline several further steps that need to be taken in order to improve the physical realism and numerical accuracy of our current 3D-NLTE calculations.

  20. LTE-advanced random access mechanism for M2M communication: A review

    NASA Astrophysics Data System (ADS)

    Mustafa, Rashid; Sarowa, Sandeep; Jaglan, Reena Rathee; Khan, Mohammad Junaid; Agrawal, Sunil

    2016-03-01

    Machine Type Communications (MTC) enables one or more self-sufficient machines to communicate directly with one another without human interference. MTC applications include smart grid, security, e-Health and intelligent automation system. To support huge numbers of MTC devices, one of the challenging issues is to provide a competent way for numerous access in the network and to minimize network overload. In this article, the different control mechanisms for overload random access are reviewed to avoid congestion caused by random access channel (RACH) of MTC devices. However, past and present wireless technologies have been engineered for Human-to-Human (H2H) communications, in particular, for transmission of voice. Consequently the Long Term Evolution (LTE) -Advanced is expected to play a central role in communicating Machine to Machine (M2M) and are very optimistic about H2H communications. Distinct and unique characteristics of M2M communications create new challenges from those in H2H communications. In this article, we investigate the impact of massive M2M terminals attempting random access to LTE-Advanced all at once. We discuss and review the solutions to alleviate the overload problem by Third Generation Partnership Project (3GPP). As a result, we evaluate and compare these solutions that can effectively eliminate the congestion on the random access channel for M2M communications without affecting H2H communications.

  1. NEON AND CNO ABUNDANCES FOR EXTREME HELIUM STARS-A NON-LTE ANALYSIS

    SciTech Connect

    Pandey, Gajendra; Lambert, David L. E-mail: dll@astro.as.utexas.edu

    2011-02-01

    A non-LTE (NLTE) abundance analysis was carried out for three extreme helium stars (EHes): BD+10{sup 0} 2179, BD-9{sup 0} 4395, and LS IV+6{sup 0} 002, from their optical spectra with NLTE model atmospheres. NLTE TLUSTY model atmospheres were computed with H, He, C, N, O, and Ne treated in NLTE. Model atmosphere parameters were chosen from consideration of fits to observed He I line profiles and ionization equilibria of C and N ions. The program SYNSPEC was then used to determine the NLTE abundances for Ne as well as H, He, C, N, and O. LTE neon abundances from Ne I lines in the EHes: LSE 78, V1920 Cyg, HD 124448, and PV Tel, are derived from published models and an estimate of the NLTE correction applied to obtain the NLTE Ne abundance. We show that the derived abundances of these key elements, including Ne, are well matched with semi-quantitative predictions for the EHe resulting from a cold merger (i.e., no nucleosynthesis during the merger) of an He white dwarf with a C-O white dwarf.

  2. Improvements in Modeling Au Sphere Non-LTE X-ray Emission

    SciTech Connect

    Rosen, M D; Scott, H A; Suter, L J; Hansen, S B

    2008-10-30

    We've previously reported on experiments at the Omega laser at URLLE, in which 1.0 mm in diameter, Au coated, spheres, were illuminated at either 10{sup 14} W/cm{sup 2} (10 kJ/3 ns) or at 10{sup 15} W/cm{sup 2} (30 kJ/1 ns). Spectral information on the 1 keV thermal x-rays, as well as the multi-keV M-band were obtained. We compared a variety of non-LTE atomic physics packages to this data with varying degrees of success. In this paper we broaden the scope of the investigation, and compare the data to newer models: (1) An improved Detailed Configuration Accounting (DCA) method; and (2) This model involves adjustments to the standard XSN non-LTE model which lead to a better match of coronal emission as calculated by XSN to that calculated by SCRAM, a more sophisticated stand-alone model. We show some improvements in the agreement with Omega data when using either of these new approaches.

  3. Long-term effectiveness of a multi-use marine protected area on reef fish assemblages and fisheries landings.

    PubMed

    Rife, Alexis N; Aburto-Oropeza, Octavio; Hastings, Philip A; Erisman, Brad; Ballantyne, Ford; Wielgus, Jeffrey; Sala, Enric; Gerber, Leah

    2013-03-15

    The Loreto Bay National Park (LBNP) is a large, multi-use marine protected area in the Gulf of California, Mexico, where several types of small-scale commercial and recreational fishing are allowed, but where less than 1% of the park is totally protected from fishing. The LBNP was created in 1996; its management plan was completed in 2000, but it was not effectively implemented and enforced until 2003. Between 1998 and 2010, we monitored reef fish populations annually at several reefs inside and outside the LBNP to measure the effects of the park on fish assemblages. We also evaluated reported fisheries landings within the LBNP for the same time series. Our results show that reef fish biomass increased significantly after protection at a small no-take site at LBNP relative to the rest of the park. However, the multi-use part of LBNP where fishing is allowed (99% of its surface) has had no measurable effect on reef fish biomass relative to open access sites outside the park boundaries. Reported fisheries landings have decreased within the park while increasing in nearby unprotected areas. Although the current partial protection management regime has not allowed for reef fish populations to recover despite 15 years as a "protected area," we conclude that LBNP's regulations and management have maintained the conditions of the ecosystem that existed when the park was established. These results suggest that community livelihoods have been sustained, but a re-evaluation of the multi-use management strategy, particularly the creation of larger no-take zones and better enforcement, is needed to improve the reef fish populations in the park in order to ensure sustainable fisheries far into the future. These recommendations can be applied to all multi-use MPAs in Mexico where ecosystem recovery is not occurring despite maintenance of fish stocks. PMID:23416447

  4. An Architecture For Shared Multi-User Client Rendering Of Massive Geodatasets

    NASA Astrophysics Data System (ADS)

    Al-Naser, A.; Brooke, J.; Rasheed, M.; Irving, D. H.

    2012-12-01

    We are developing a novel data-centric visualization architecture to allow interactive exploration of geophysical data. Our method allows multiple users to collaborate in a lightweight, loosely-coupled and highly scalable environment. We choose 3D seismic data for our case study. Existing visualization solutions for data exploratory tasks are mainly application-centric rather than data-centric. They typically store large datasets on users' local machines for fast access. Additionally, data objects that are the focus of study, e.g. seismic surveys and interpreted geological features, are managed as objects that are independent of the primary data. Thus multi-user collaborations where different users visually share their geological interpretations are handled inefficiently since objects from each interpretation are stored as independent discrete objects. These objects may be stored separately from the primary data, e.g. on local disks, ensuring a coherent multi-user view is difficult. Our visual analytic method places a central data structure built on a Massively Parallel Processing (MPP) relational database at the heart of the visualization architecture. This structure allows us to develop the following efficient methods for data retrieval and display: -global hashing for spatial reference on all datasets -interpretation tagging which accumulate user interpretation into the database -multi-user concurrent access allowing parallel multi-threading queries In our data structure, data elements are indexed on their geolocations by a hashing algorithm. The hashing algorithm determines the location of the required row through hashing functions without a construction or any storage complexity. This is unlike other conventional indexing algorithms such as bitmapping or tree-based methods where construction and storage (of the index table) complexity varies between O(n) and O(n log n) where n is the size of the dataset. Also, we replace the geometric objects formed as a

  5. The ALI-ARMS Code for Modeling Atmospheric non-LTE Molecular Band Emissions: Current Status and Applications

    NASA Technical Reports Server (NTRS)

    Kutepov, A. A.; Feofilov, A. G.; Manuilova, R. O.; Yankovsky, V. A.; Rezac, L.; Pesnell, W. D.; Goldberg, R. A.

    2008-01-01

    The Accelerated Lambda Iteration (ALI) technique was developed in stellar astrophysics at the beginning of 1990s for solving the non-LTE radiative transfer problem in atomic lines and multiplets in stellar atmospheres. It was later successfully applied to modeling the non-LTE emissions and radiative cooling/heating in the vibrational-rotational bands of molecules in planetary atmospheres. Similar to the standard lambda iterations ALI operates with the matrices of minimal dimension. However, it provides higher convergence rate and stability due to removing from the iterating process the photons trapped in the optically thick line cores. In the current ALI-ARMS (ALI for Atmospheric Radiation and Molecular Spectra) code version additional acceleration of calculations is provided by utilizing the opacity distribution function (ODF) approach and "decoupling". The former allows replacing the band branches by single lines of special shape, whereas the latter treats non-linearity caused by strong near-resonant vibration-vibrational level coupling without additional linearizing the statistical equilibrium equations. Latest code application for the non-LTE diagnostics of the molecular band emissions of Earth's and Martian atmospheres as well as for the non-LTE IR cooling/heating calculations are discussed.

  6. Airway responsiveness to leukotriene C4 (LTC4), leukotriene E4 (LTE4) and histamine in aspirin-sensitive asthmatic subjects.

    PubMed

    Christie, P E; Schmitz-Schumann, M; Spur, B W; Lee, T H

    1993-11-01

    We wanted to determine whether the airway response to inhaled leukotriene C4 (LTC4) is similar to inhaled leukotriene E4 (LTE4) in aspirin-sensitive asthma and, therefore, determined airway responsiveness to histamine, LTC4 and LTE4 in seven aspirin-sensitive subjects and 13 control asthmatic subjects, who were tolerant of aspirin. The concentration of inhaled lysine-aspirin which produced a 15% fall in forced expiratory volume in one second (FEV1) (PC15) was determined in aspirin-sensitive asthmatic subjects. The dose of histamine, LTC4 and LTE4 which produced a 35% fall in specific airways conductance (PD35sGaw) was determined by linear interpolation from the log dose response curve. There was no correlation between the PC15 for lysine-aspirin and the airway reactivity to inhaled LTC4 or LTE4. There was no difference in airway response to histamine and LTC4 between any of the groups of asthmatic subjects. There was a rank order of potency LTC4 > LTE4 > histamine in both groups, with LTC4 approximately 1,000 fold more potent than histamine in both groups. Aspirin-sensitive asthmatic subjects were significantly more responsive to LTE4 (p = 0.02) than aspirin-tolerant asthmatic subjects. The relative responsiveness of LTE4 to histamine (PD35 histamine/PD35 LTE4) was significantly greater in aspirin-sensitive asthmatic subjects compared to aspirin-tolerant asthmatic subjects (p = 0.05). There was no difference in relative responsiveness of LTC4 to histamine between aspirin-sensitive or aspirin-tolerant asthmatic subjects. We conclude that the airways of aspirin-sensitive asthmatic subjects demonstrate a selective hyperresponsiveness to LTE4, which is not observed for LTC4. PMID:8112440

  7. A High-Throughput Biological Calorimetry Core: Steps to Startup, Run, and Maintain a Multiuser Facility.

    PubMed

    Yennawar, Neela H; Fecko, Julia A; Showalter, Scott A; Bevilacqua, Philip C

    2016-01-01

    Many labs have conventional calorimeters where denaturation and binding experiments are setup and run one at a time. While these systems are highly informative to biopolymer folding and ligand interaction, they require considerable manual intervention for cleaning and setup. As such, the throughput for such setups is limited typically to a few runs a day. With a large number of experimental parameters to explore including different buffers, macromolecule concentrations, temperatures, ligands, mutants, controls, replicates, and instrument tests, the need for high-throughput automated calorimeters is on the rise. Lower sample volume requirements and reduced user intervention time compared to the manual instruments have improved turnover of calorimetry experiments in a high-throughput format where 25 or more runs can be conducted per day. The cost and efforts to maintain high-throughput equipment typically demands that these instruments be housed in a multiuser core facility. We describe here the steps taken to successfully start and run an automated biological calorimetry facility at Pennsylvania State University. Scientists from various departments at Penn State including Chemistry, Biochemistry and Molecular Biology, Bioengineering, Biology, Food Science, and Chemical Engineering are benefiting from this core facility. Samples studied include proteins, nucleic acids, sugars, lipids, synthetic polymers, small molecules, natural products, and virus capsids. This facility has led to higher throughput of data, which has been leveraged into grant support, attracting new faculty hire and has led to some exciting publications. PMID:26794364

  8. Exploring the Use of Individualized, Reflective Guidance In an Educational Multi-User Virtual Environment

    NASA Astrophysics Data System (ADS)

    Nelson, Brian C.

    2007-02-01

    This study examines the patterns of use and potential impact of individualized, reflective guidance in an educational Multi-User Virtual Environment (MUVE). A guidance system embedded within a MUVE-based scientific inquiry curriculum was implemented with a sample of middle school students in an exploratory study investigating (a) whether access to the guidance system was associated with improved learning, (b) whether students viewing more guidance messages saw greater improvement on content tests than those viewing less, and (c) whether there were any differences in guidance use among boys and girls. Initial experimental findings showed that basic access to individualized guidance used with a MUVE had no measurable impact on learning. However, post-hoc exploratory analyses indicated that increased use of the system among those with access to it was positively associated with content test score gains. In addition, differences were found in overall learning outcomes by gender and in patterns of guidance use by boys and girls, with girls outperforming boys across a spectrum of guidance system use. Based on these exploratory findings, the paper suggests design guidelines for the development of guidance systems embedded in MUVEs and outlines directions for further research.

  9. Development and experimental validation of downlink multiuser MIMO-OFDM in gigabit wireless LAN systems

    NASA Astrophysics Data System (ADS)

    Ishihara, Koichi; Asai, Yusuke; Kudo, Riichi; Ichikawa, Takeo; Takatori, Yasushi; Mizoguchi, Masato

    2013-12-01

    Multiuser multiple-input multiple-output (MU-MIMO) has been proposed as a means to improve spectrum efficiency for various future wireless communication systems. This paper reports indoor experimental results obtained for a newly developed and implemented downlink (DL) MU-MIMO orthogonal frequency division multiplexing (OFDM) transceiver for gigabit wireless local area network systems in the microwave band. In the transceiver, the channel state information (CSI) is estimated at each user and fed back to an access point (AP) on a real-time basis. At the AP, the estimated CSI is used to calculate the transmit beamforming weight for DL MU-MIMO transmission. This paper also proposes a recursive inverse matrix computation scheme for computing the transmit weight in real time. Experiments with the developed transceiver demonstrate its feasibility in a number of indoor scenarios. The experimental results clarify that DL MU-MIMO-OFDM transmission can achieve a 972-Mbit/s transmission data rate with simple digital signal processing of single-antenna users in an indoor environment.

  10. Prototyping Tool for Web-Based Multiuser Online Role-Playing Game

    NASA Astrophysics Data System (ADS)

    Okamoto, Shusuke; Kamada, Masaru; Yonekura, Tatsuhiro

    This letter proposes a prototyping tool for Web-based Multiuser Online Role-Playing Game (MORPG). The design goal is to make this tool simple and powerful. The tool is comprised of a GUI editor, a translator and a runtime environment. The GUI editor is used to edit state-transition diagrams, each of which defines the behavior of the fictional characters. The state-transition diagrams are translated into C program codes, which plays the role of a game engine in RPG system. The runtime environment includes PHP, JavaScript with Ajax and HTML. So the prototype system can be played on the usual Web browser, such as Fire-fox, Safari and IE. On a click or key press by a player, the Web browser sends it to the Web server to reflect its consequence on the screens which other players are looking at. Prospected users of this tool include programming novices and schoolchildren. The knowledge or skill of any specific programming languages is not required to create state-transition diagrams. Its structure is not only suitable for the definition of a character behavior but also intuitive to help novices understand. Therefore, the users can easily create Web-based MORPG system with the tool.

  11. Computer Simulation and Field Experiment for Downlink Multiuser MIMO in Mobile WiMAX System

    PubMed Central

    Yamaguchi, Kazuhiro; Nagahashi, Takaharu; Akiyama, Takuya; Matsue, Hideaki; Uekado, Kunio; Namera, Takakazu; Fukui, Hiroshi; Nanamatsu, Satoshi

    2015-01-01

    The transmission performance for a downlink mobile WiMAX system with multiuser multiple-input multiple-output (MU-MIMO) systems in a computer simulation and field experiment is described. In computer simulation, a MU-MIMO transmission system can be realized by using the block diagonalization (BD) algorithm, and each user can receive signals without any signal interference from other users. The bit error rate (BER) performance and channel capacity in accordance with modulation schemes and the number of streams were simulated in a spatially correlated multipath fading environment. Furthermore, we propose a method for evaluating the transmission performance for this downlink mobile WiMAX system in this environment by using the computer simulation. In the field experiment, the received power and downlink throughput in the UDP layer were measured on an experimental mobile WiMAX system developed in Azumino City in Japan. In comparison with the simulated and experimented results, the measured maximum throughput performance in the downlink had almost the same performance as the simulated throughput. It was confirmed that the experimental mobile WiMAX system for MU-MIMO transmission successfully increased the total channel capacity of the system. PMID:26421311

  12. Computer Simulation and Field Experiment for Downlink Multiuser MIMO in Mobile WiMAX System.

    PubMed

    Yamaguchi, Kazuhiro; Nagahashi, Takaharu; Akiyama, Takuya; Matsue, Hideaki; Uekado, Kunio; Namera, Takakazu; Fukui, Hiroshi; Nanamatsu, Satoshi

    2015-01-01

    The transmission performance for a downlink mobile WiMAX system with multiuser multiple-input multiple-output (MU-MIMO) systems in a computer simulation and field experiment is described. In computer simulation, a MU-MIMO transmission system can be realized by using the block diagonalization (BD) algorithm, and each user can receive signals without any signal interference from other users. The bit error rate (BER) performance and channel capacity in accordance with modulation schemes and the number of streams were simulated in a spatially correlated multipath fading environment. Furthermore, we propose a method for evaluating the transmission performance for this downlink mobile WiMAX system in this environment by using the computer simulation. In the field experiment, the received power and downlink throughput in the UDP layer were measured on an experimental mobile WiMAX system developed in Azumino City in Japan. In comparison with the simulated and experimented results, the measured maximum throughput performance in the downlink had almost the same performance as the simulated throughput. It was confirmed that the experimental mobile WiMAX system for MU-MIMO transmission successfully increased the total channel capacity of the system. PMID:26421311

  13. Multi-user satellite communications system using an innovative compressive receiver

    NASA Technical Reports Server (NTRS)

    Staples, Edward J.

    1992-01-01

    There is a need for an onboard simultaneous multi-channel demodulation system for a satellite communications system. Studies indicate that Convolve Multiply Convolve (CMC) filtering with surface acoustic wave (SAW) dispersive delay lines will eliminate the necessity of onboard satellite channelized filters of complex fourier transform processors. The reason for choosing the CMC technique is its ability to perform Fourier transformations in a shorter time with less space and power consumption than digital Fourier transform processors. Each ground terminal in this multi-users communications system is remotely located and operates independently; hence, a method of synchronizing the transmission of these users is presented which utilizes the existing Global Positioning System (GPS) system. Each ground user is equipped with a low cost ground terminal that has a synchronization subsystem attached to it. The system design of an onboard Multi-channel Receiver and Demodulator utilizes Quadrature Phase Shift Keying (QPSK) as the modulation technique. This technique provides the best figure of merit, i.e., the lowest transmitter power requirement per communication channel.

  14. FEANICS: A Multi-User Facility For Conducting Solid Fuel Combustion Experiments On ISS

    NASA Technical Reports Server (NTRS)

    Frate, David T.; Tofil, Todd A.

    2001-01-01

    The Destiny Module on the International Space Station (ISS) will soon be home for the Fluids and Combustion Facility's (FCF) Combustion Integrated Rack (CIR), which is being developed at the NASA Glenn Research Center in Cleveland, Ohio. The CIR will be the platform for future microgravity combustion experiments. A multi-user mini-facility called FEANICS (Flow Enclosure Accommodating Novel Investigations in Combustion of Solids) will also be built at NASA Glenn. This mini-facility will be the primary means for conducting solid fuel combustion experiments in the CIR on ISS. The main focus of many of these solid combustion experiments will be to conduct basic and applied scientific investigations in fire-safety to support NASA's Bioastronautics Initiative. The FEANICS project team will work in conjunction with the CIR project team to develop upgradeable and reusable hardware to meet the science requirements of current and future investigators. Currently, there are six experiments that are candidates to use the FEANICS mini-facility. This paper will describe the capabilities of this mini-facility and the type of solid combustion testing and diagnostics that can be performed.

  15. A multi-user real time inventorying system for radioactive materials: a networking approach.

    PubMed

    Mehta, S; Bandyopadhyay, D; Hoory, S

    1998-01-01

    A computerized system for radioisotope management and real time inventory coordinated across a large organization is reported. It handles hundreds of individual users and their separate inventory records. Use of highly efficient computer network and database technologies makes it possible to accept, maintain, and furnish all records related to receipt, usage, and disposal of the radioactive materials for the users separately and collectively. The system's central processor is an HP-9000/800 G60 RISC server and users from across the organization use their personal computers to login to this server using the TCP/IP networking protocol, which makes distributed use of the system possible. Radioisotope decay is automatically calculated by the program, so that it can make the up-to-date radioisotope inventory data of an entire institution available immediately. The system is specifically designed to allow use by large numbers of users (about 300) and accommodates high volumes of data input and retrieval without compromising simplicity and accuracy. Overall, it is an example of a true multi-user, on-line, relational database information system that makes the functioning of a radiation safety department efficient. PMID:9415583

  16. Multi-Objective Multi-User Scheduling for Space Science Missions

    NASA Technical Reports Server (NTRS)

    Johnston, Mark D.; Giuliano, Mark

    2010-01-01

    We have developed an architecture called MUSE (Multi-User Scheduling Environment) to enable the integration of multi-objective evolutionary algorithms with existing domain planning and scheduling tools. Our approach is intended to make it possible to re-use existing software, while obtaining the advantages of multi-objective optimization algorithms. This approach enables multiple participants to actively engage in the optimization process, each representing one or more objectives in the optimization problem. As initial applications, we apply our approach to scheduling the James Webb Space Telescope, where three objectives are modeled: minimizing wasted time, minimizing the number of observations that miss their last planning opportunity in a year, and minimizing the (vector) build up of angular momentum that would necessitate the use of mission critical propellant to dump the momentum. As a second application area, we model aspects of the Cassini science planning process, including the trade-off between collecting data (subject to onboard recorder capacity) and transmitting saved data to Earth. A third mission application is that of scheduling the Cluster 4-spacecraft constellation plasma experiment. In this paper we describe our overall architecture and our adaptations for these different application domains. We also describe our plans for applying this approach to other science mission planning and scheduling problems in the future.

  17. Physical conditions in the NGC 6334 molecular cloud derived from non-LTE NH3(J,K)=(1,1) transitions

    NASA Astrophysics Data System (ADS)

    Caproni, Anderson; Abraham, Zulema; Vilas-Boas, Jose W. S.

    The high signal-to-noise ratio of the NH3(J,K) = (1,1) spectra from NGC 6334 have allowed at a first time a detailed study of departures from LTE conditions in this molecular cloud. Differences in the line shapes have shown that the surveyed region is composed of at least three overlapped sources in different stages of star formation. Comparison between physical parameters of NGC6334 derived from LTE and non-LTE conditions are presented and discussed here.

  18. Performance analysis of conventional CMA and RLS in single carrier LTE uplink systems

    NASA Astrophysics Data System (ADS)

    Reddy P, Jaswini; Kotte, Swathi; Gannamaneni, Geetha Chowdary; Talluri, Kalyan Chakravarthy

    2011-10-01

    In wireless communication, channel equalization is one of the most challenging tasks because the broadcast channels are often subjected to multipath fading and several bandwidth limitations. Our project is mainly concerned with the Single Carrier Long Term Evolution (SC-LTE) uplink system model and its performance analysis when Fractionally Spaced Constant Modulus Algorithm (FS-CMA) and Recursive Least Squares Algorithm (RLS) are implemented. FS-CMA (CMA (1, 2) and CMA (2, 2)) and RLS algorithms are used individually to eliminate noise caused by multipath fading and Additive White Gaussian Noise (AWGN) in the stationary channel. The performance of conventional FS-CMA and RLS algorithm are compared using Bit Error Rate (BER) vs. Signal to Noise Ratio (SNR), Convergence, Equalizer output, Peak to Average Power Ratio (PAPR) vs. SNR.

  19. Non-LTE Steady-State Kinetics of He-Air Atmospheric Pressure Plasmas

    NASA Astrophysics Data System (ADS)

    Petrova, Tzvetelina; Petrov, George; Gillman, Eric; Boris, David; Hernández, Sandra; Walton, Scott

    2015-11-01

    A non-LTE, steady-state collisional-radiative kinetics model is developed to study discharges produced in mixtures of He, N2 and O2 (He-Air) at atmospheric pressures. The model is based on a self-consistent solution of coupled Boltzmann equation for the electron energy distribution function, electron energy balance equation, gas thermal balance equation, and a system of non-linear equations for species that govern plasma chemistry (electrons, ions, radicals, atoms and molecules in ground and excited states). The model and results can be applied to study a variety of atmospheric pressure plasmas generated in He-Air mixtures, such as plasma jets, dielectric barrier discharges, laser-induced plasmas, microwave plasmas, etc. In this talk, collisional rates and species densities are obtained as a function of He-to-air ratio and the results are benchmarked against available experimental data. Work supported by the NRL Base Program.

  20. Benchmark Measurements of the Ionization Balance of Non-LTE Gold

    SciTech Connect

    Heeter, R F; Hansen, S B; Fournier, K B; Foord, M E; Froula, D H; Mackinnon, A J; May, M J; Schneider, M B; Young, B F

    2007-04-20

    The authors present a series of benchmark measurements of the ionization balance of well characterized gold plasmas with and without external radiation fields at electron densities near 10{sup 21} cm{sup -3} and various electron temperatures spanning the range 0.8 to 2.4 keV. They have analyzed time- and space-resolved M-shell gold emission spectra using a sophisticated collisional-radiative model with hybrid level structure, finding average ion changes ranging from 42 to 50. At the lower temperatures, the spectra exhibit significant sensitivity to external radiation fields and include emission features from complex N-shell ions not previously studied at these densities. The measured spectra and inferred provide a stringent test for non-local thermodynamic equilibrium (non-LTE) models of complex high-Z ions.

  1. Physics of Solar Prominences: I-Spectral Diagnostics and Non-LTE Modelling

    NASA Technical Reports Server (NTRS)

    Labrosse, N.; Heinzel, P.; Vial, J.-C,; Kucera, T.; Parenti, S.; Gunar, S.; Schmieder, B.; Kilper, G.

    2010-01-01

    This review paper outlines background information and covers recent advances made via the analysis of spectra and images of prominence plasma and the increased sophistication of non-LTE (i.e. when there is a departure from Local Thermodynamic Equilibrium) radiative transfer models. We first describe the spectral inversion techniques that have been used to infer the plasma parameters important for the general properties of the prominence plasma in both its cool core and the hotter prominence-corona transition region. We also review studies devoted to the observation of bulk motions of the prominence plasma and to the determination of prominence mass. However, a simple inversion of spectroscopic data usually fails when the lines become optically thick at certain wavelengths. Therefore, complex

  2. Augmented Twin-Nonlinear Two-Box Behavioral Models for Multicarrier LTE Power Amplifiers

    PubMed Central

    2014-01-01

    A novel class of behavioral models is proposed for LTE-driven Doherty power amplifiers with strong memory effects. The proposed models, labeled augmented twin-nonlinear two-box models, are built by cascading a highly nonlinear memoryless function with a mildly nonlinear memory polynomial with cross terms. Experimental validation on gallium nitride based Doherty power amplifiers illustrates the accuracy enhancement and complexity reduction achieved by the proposed models. When strong memory effects are observed, the augmented twin-nonlinear two-box models can improve the normalized mean square error by up to 3 dB for the same number of coefficients when compared to state-of-the-art twin-nonlinear two-box models. Furthermore, the augmented twin-nonlinear two-box models lead to the same performance as previously reported twin-nonlinear two-box models while requiring up to 80% less coefficients. PMID:24624047

  3. A new method of calculating multi-level non-LTE line formation

    NASA Astrophysics Data System (ADS)

    Wu, G. Q.

    1992-03-01

    This paper introduces a new method of solving the equation of multi-level non-LTE radiative transfer subject to constraints. This method is based on the combination of the advantages of the complete linearization method by Auer and Mihalas (1969) and the simple separated-iteration technique (Mihalas, 1978). First, linearize the equation of radiative transfer and constraints, respectively, then solve the linearized equation of the radiative transfer and linearized constraints, separately. It overcomes the disadvantages of requiring the simultaneous solution of the corresponding equations by the complete linearization method and the poor convergence of the simple separated-iteration technique. Therefore, it not only can deal with complex models, but also has a high speed of convergence in the calculation of multi-level NLTE line formation.

  4. A conjugate gradient method for solving the non-LTE line radiation transfer problem

    NASA Astrophysics Data System (ADS)

    Paletou, F.; Anterrieu, E.

    2009-12-01

    This study concerns the fast and accurate solution of the line radiation transfer problem, under non-LTE conditions. We propose and evaluate an alternative iterative scheme to the classical ALI-Jacobi method, and to the more recently proposed Gauss-Seidel and successive over-relaxation (GS/SOR) schemes. Our study is indeed based on applying a preconditioned bi-conjugate gradient method (BiCG-P). Standard tests, in 1D plane parallel geometry and in the frame of the two-level atom model with monochromatic scattering are discussed. Rates of convergence between the previously mentioned iterative schemes are compared, as are their respective timing properties. The smoothing capability of the BiCG-P method is also demonstrated.

  5. The Second Stellar Spectrum and the non-LTE Problem of the 2nd Kind

    NASA Astrophysics Data System (ADS)

    Trujillo Bueno, Javier

    2009-09-01

    This paper presents an overview of the radiative transfer problem of calculating the spectral line intensity and polarization that emerges from a (generally magnetized) astrophysical plasma composed of atoms and molecules whose excitation state is significantly influenced by radiative transitions produced by an anisotropic radiation field. The numerical solution of this non-LTE problem of the 2nd kind is facilitating the physical understanding of the second solar spectrum and the exploration of the complex magnetism of the extended solar atmosphere, but much more could be learned if high-sensitivity polarimeters were developed also for the present generation of night-time telescopes. Interestingly, I find that the population ratio between the levels of some resonance line transitions can be efficiently modulated by the inclination of a weak magnetic field when the anisotropy of the incident radiation is significant, something that could provide a new diagnostic tool in astrophysics.

  6. LTE model atmospheres with new opacities. I. Methods and general properties

    NASA Astrophysics Data System (ADS)

    Behara, N. T.; Jeffery, C. S.

    2006-05-01

    We describe an opacity sampled version of the LTE model atmosphere code sterne with revised continuous opacities. In particular, we examine the results of replacing the existing treatment of the continuous opacities which followed the method of Kurucz (1970, SAOSR, No. 309) and Peach (1970, MNRAS, 73, 1), with photoionization cross-sections from the Opacity Project and the IRON Project, and the effects of substituting an opacity distribution function method for treating the line opacities with an opacity sampling method. In studying the application of these new models to atmospheres with hydrogen-rich and extreme chemical compositions, we find the new opacity treatment increases the temperature in the line forming region by up to 3000 K for extremely hydrogen-poor stars and up to 1250 K for hydrogen-rich stars with T_eff = 30 000 K and log g = 3.00. This translates into systematically cooler effective temperature measurements for these types of stars.

  7. Non-LTE Analysis of Interstellar Line Spectra of SiO

    NASA Astrophysics Data System (ADS)

    Zhang, Ziwei; Stancil, Phillip C.

    2016-01-01

    SiO emission lines are important probes of chemical processes in diverse astrophysical environments. In circumstellar outflows of AGB stars, the production of silicate grains is preceded by SiO formation, making SiO a useful measure of Si depletion. SiO is also commonly observed in shocks associated with the outflows of young stellar objects, both low- and high-mass. To model SiO emission for non-LTE conditions requires collisional rate coefficients due to H2 impact which are currently unavailable. Unknown collisional rate coefficients are often estimated from known systems. For the case of SiO-H2, rate coefficients have previously been adapted from a different collider, He (Dayau & Balanca 2006), based on a reduced-mass scaling approach. Recently it has been suggested that scaling via the interaction potential well depth and the reduced masses of the collisional systems may be more reliable (Walker et al. 2014). Using the non-LTE spectral modeling package Radex (van der Tak et al. 2007), we construct diagnostic plots of SiO line ratios using SiO-H2 collisional rate coefficients based on (i) reduced-mass scaling from the LAMDA database, (ii) potential well-depth scaling, and (iii) a more comprehensive input with multiple colliders (H2, He and H). Our goal is to give a more rigorous approach to SiO line emission simulations to better understand Si chemistry, dust formation/destruction, and other astrophysical processes.This work was supported by NASA ATP grant NNX15AI61G.

  8. Investigation on Interference Coordination Employing Almost Blank Subframes in Heterogeneous Networks for LTE-Advanced Downlink

    NASA Astrophysics Data System (ADS)

    Miki, Nobuhiko; Saito, Yuya; Shirakabe, Masashige; Morimoto, Akihito; Abe, Tetsushi

    This paper investigates the application of inter-cell interference coordination (ICIC) in heterogeneous networks for the LTE-Advanced downlink where picocells are overlaid onto macrocells. In LTE-Advanced, in order to perform ICIC, almost blank subframes (ABSs) are employed, where only the cell-specific reference signal (CRS) is transmitted to protect the subframes in the picocells from severe interference from the macrocells. Furthermore, multicast/broadcast over single-frequency network (MBSFN) subframes are employed to reduce the interference of the CRS on the data channel, although the control channel still suffers from interference from the CRS. When the cell range expansion (CRE), which offload the UEs from macrocells to picocells, is used to improve the system performance, the influence from the CRS increases. In order to assess the influence, the required CRE bias to improve the data channel is investigated based on a system-level simulation under various conditions such as the number of picocells, the protected subframe ratio, and the user distribution. The simulation results show that the cell-edge user throughput is improved with the CRE bias of more than 8dB, employing ABSs. Furthermore, simulation results show that one dominant source of interference is observed for the sets of user equipment (UEs) connected to the picocells via CRE with such a bias value. Based on observation, the influence that the CRS has on the control channel, i.e., physical control format indicator channel (PCFICH), and physical downlink control channel (PDCCH) is investigated based on a link-level simulation combined with a system-level simulation. The simulation results show that protecting the PCFICH is very important compared to protecting the PDCCH, since the block error rate (BLER) performance of the PCFICH becomes worse than the required BLER of 10-3 to support various conditions, although the BLER performance of the PDCCH can exceed the required BLER of 10-2 by spanning

  9. Model estimates of inelastic calcium-hydrogen collision data for non-LTE stellar atmospheres modeling

    NASA Astrophysics Data System (ADS)

    Belyaev, A. K.; Yakovleva, S. A.; Guitou, M.; Mitrushchenkov, A. O.; Spielfiedel, A.; Feautrier, N.

    2016-03-01

    Aims: Inelastic processes in low-energy Ca + H and Ca+ + H- collisions are treated for the states from the ground state up to the ionic state with the aim to provide rate coefficients needed for non-LTE modeling of Ca in cool stellar atmospheres. Methods: The electronic molecular structure was determined using a recently proposed model approach that is based on an asymptotic method. Nonadiabatic nuclear dynamics were treated by means of multichannel formulas, based on the Landau-Zener model for nonadiabatic transition probabilities. Results: The cross sections and rate coefficients for inelastic processes in Ca + H and Ca+ + H- collisions were calculated for all transitions between 17 low-lying covalent states plus the ionic state. It is shown that the highest rate coefficient values correspond to the excitation, de-excitation, ion-pair formation, and mutual neutralization processes involving the Ca(4s5s 1,3S) and the ionic Ca+ + H- states. The next group with the second highest rate coefficients includes the processes involving the Ca(4s5p 1,3P), Ca(4s4d 1,3D), and Ca(4s4p 1P) states. The processes from these two groups are likely to be important for non-LTE modeling. Tables 2-11 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/587/A114

  10. Tunable optical frequency comb enabled scalable and cost-effective multiuser orthogonal frequency-division multiple access passive optical network with source-free optical network units.

    PubMed

    Chen, Chen; Zhang, Chongfu; Liu, Deming; Qiu, Kun; Liu, Shuang

    2012-10-01

    We propose and experimentally demonstrate a multiuser orthogonal frequency-division multiple access passive optical network (OFDMA-PON) with source-free optical network units (ONUs), enabled by tunable optical frequency comb generation technology. By cascading a phase modulator (PM) and an intensity modulator and dynamically controlling the peak-to-peak voltage of a PM driven signal, a tunable optical frequency comb source can be generated. It is utilized to assist the configuration of a multiple source-free ONUs enhanced OFDMA-PON where simultaneous and interference-free multiuser upstream transmission over a single wavelength can be efficiently supported. The proposed multiuser OFDMA-PON is scalable and cost effective, and its feasibility is successfully verified by experiment. PMID:23027243

  11. Identification of an Orthogonal Peptide Binding Motif for Biarsenical Multiuse Affinity Probes

    SciTech Connect

    Chen, Baowei; Cao, Haishi; Yan, Ping; Mayer, M. Uljana; Squier, Thomas C.

    2007-07-01

    Biarsenical multiuse affinity probes (MAPs) complexed with ethanedithiol (EDT) permit the selective cellular labeling of proteins engineered with tetracysteine motifs, but are limited by the availability of a single binding motif (i.e., CCPGCC or PG tag) that prevents the differential labeling of co-expressed proteins. To overcome this problem, we have used a high-throughput peptide screen to identify an alternate binding motif (i.e., CCKACC or KA tag), which has a similar brightness to the classical sequence upon MAP binding, but displays altered rates and affinities of association that permit the differential labeling of these peptide sequences by the red probe 4,5-bis(1,3,2-dithiarsolan-2-yl)-resorufin (ReAsH-EDT2) or its green cognate 4’,5’-bis(1,3,2-dithoarsolan-2-yl)fluorescein-(1,2-ethanedithiol)2 (FLAsH-EDT2). The utility of this labeling strategy was demonstrated following the expression of PG- and KA-tagged subunits of RNA polymerase expressed in E. coli. Specific labeling of two subunits of RNA polymerase in cellular lysates was achieved, whereby ReAsH-EDT2 is shown to selectively label the PG-tag on RNA polymerase alpha subunit prior to the labeling of the KA-tag sequence of the beta subunit of RNA polymerase with FlAsH-EDT2. These results demonstrate the ability to selectively label multiple individual proteins with orthogonal sequence tags in complex cellular lystates with spectroscopically distinct MAPs, and indicate the absolute specificity of ReAsH to target expressed proteins with essentially no nonspecific binding interactions.

  12. Quantum key distribution in a multi-user network at gigahertz clock rates

    NASA Astrophysics Data System (ADS)

    Fernandez, Veronica; Gordon, Karen J.; Collins, Robert J.; Townsend, Paul D.; Cova, Sergio D.; Rech, Ivan; Buller, Gerald S.

    2005-07-01

    In recent years quantum information research has lead to the discovery of a number of remarkable new paradigms for information processing and communication. These developments include quantum cryptography schemes that offer unconditionally secure information transport guaranteed by quantum-mechanical laws. Such potentially disruptive security technologies could be of high strategic and economic value in the future. Two major issues confronting researchers in this field are the transmission range (typically <100km) and the key exchange rate, which can be as low as a few bits per second at long optical fiber distances. This paper describes further research of an approach to significantly enhance the key exchange rate in an optical fiber system at distances in the range of 1-20km. We will present results on a number of application scenarios, including point-to-point links and multi-user networks. Quantum key distribution systems have been developed, which use standard telecommunications optical fiber, and which are capable of operating at clock rates of up to 2GHz. They implement a polarization-encoded version of the B92 protocol and employ vertical-cavity surface-emitting lasers with emission wavelengths of 850 nm as weak coherent light sources, as well as silicon single-photon avalanche diodes as the single photon detectors. The point-to-point quantum key distribution system exhibited a quantum bit error rate of 1.4%, and an estimated net bit rate greater than 100,000 bits-1 for a 4.2 km transmission range.

  13. Simultaneous injection of stable and radioactive ions into upgraded multi-user atlas

    NASA Astrophysics Data System (ADS)

    Perry, Amichay

    Argonne Tandem Linac Accelerator System (ATLAS) is a Department of Energy (DOE) national user research facility, located at Argonne National Laboratory (ANL). Presently, Radioactive Ion Beams (RIBs) produced in the Californium Rare Isotope Breeder Upgrade (CARIBU) facility are charge bred in an Electron Cyclotron Resonance (ECR) charge breeder prior to post acceleration in ATLAS. A new state of the art Electron Beam Ion Source charge breeder, the CARIBU-EBIS charge breeder, has been developed (not in the scope of the work presented here) at ANL to replace the existing ECR charge breeder for charge breeding RIBs generated in CARIBU. The CARIBU-EBIS charge breeder is now in the final stages of offline at the Accelerator Development Test Facility (ADTF). A significant part of the commissioning effort has been devoted to testing the source by breeding singly-charged cesium ions injected from a surface ionization source. Characterization of the CARIBU-EBIS performance has been accomplished through a comparison between the measured properties of extracted beams and simulation results. Following its offline commissioning, CARIBU-EBIS will be relocated to its permanent location in ATLAS. An electrostatic transport line has been designed to transport RIBs from CARIBU and inject them into CARIBU-EBIS. In addition, modifications to the existing ATLAS Low Energy Beam Transport (LEBT) were required in order to transport the charge bred RIBs from CARIBU-EBIS to ATLAS. A proposal for upgrading ATLAS to a multi-user facility has been explored as well. In this context, beam dynamics simulations show that further modifications to the ATLAS LEBT will enable the simultaneous injection and acceleration of RIBs and stable beams in ATLAS. Furthermore, a novel technique proposed by Ostroumov et al. will allow for the acceleration of multiple charge states from CARIBU-EBIS, thereby increasing the intensity of available RIBs by up to 60%.

  14. Self-Consistent Signal-to-Noise Analysis of CDMA Multiuser Detection with M-Ary Phase-Shift Keying

    NASA Astrophysics Data System (ADS)

    Kato, Hiroyuki; Okada, Masato; Miyoshi, Seiji

    2013-02-01

    We present a theory of the performance of parallel interference cancellation (PIC) for code division multiple access (CDMA) multiuser detection with M-ary phase-shift keying (M-ary PSK) in the large-system limit. The behavior of PIC is essentially the same as that of the associative memory model. Therefore, we analyze the PIC for CDMA using self-consistent signal-to-noise analysis (SCSNA), which was developed to describe the behavior of the associative memory model. We obtain a quantitative description of the performance of PIC.

  15. Preliminary determination of the Non-LTE Calcium abundance in a sample of extremely metal-poor stars*

    NASA Astrophysics Data System (ADS)

    Spite, M.; Spite, F.; Bonifacio, P.; Caffau, E.; Andrievsky, S.; Korotin, S.; Cayrel, R.; François, P.

    2011-12-01

    The abundance ratios of the elements found in the extremely metal-poor stars (EMP) are a test of the yields predicted by the models of supernovae. For precise comparisons, it is of course preferable to avoid the approximation of LTE. The difference of LTE and NLTE profiles is displayed for three strong lines. The NLTE abundances of Ca are derived from the profiles of about 15 Ca I lines in the EMP giants and about 10 lines in the turnoff stars. The improved abundance trends are consistent with a [Ca/Fe] ratio constant vs. [Fe/H], and with a [Ca/Mg] ratio slightly declining when [Mg/H] increases. Also [Ca/Mg] presents a scatter larger than [Ca/Fe]. As far as the comparison with sulfur (another alpha elment) is concerned we find that [S/Ca] presents a scatter smaller than [S/Mg].

  16. Absolute, time-resolved emission of non-LTE L-shell spectra from Ti-doped aerogels

    NASA Astrophysics Data System (ADS)

    Back, C. A.; Feldman, U.; Weaver, J. L.; Seely, J. F.; Constantin, C.; Holland, G.; Lee, R. W.; Chung, H.-K.; Scott, H. A.

    2006-05-01

    Outstanding discrepancies between data and calculations of laser-produced plasmas in recombination have been observed since the 1980s. Although improvements in hydrodynamic modeling may reduce the discrepancies, there are indications that non-LTE atomic kinetics may be the dominant cause. Experiments to investigate non-LTE effects were recently performed at the NIKE KrF laser on low-density Ti-doped aerogels. The laser irradiated a 2 mm diameter, cylindrical sample of various lengths with a 4-ns square pulse to create a volumetrically heated plasma. Ti L-shell spectra spanning a range of 0.47 3 keV were obtained with a transmission grating coupled to Si photodiodes. The diagnostic can be configured to provide 1-dimensional spatial resolution at a single photon energy, or 18 discrete energies with a resolving power, λ/δλ of 3 20. The data are examined and compared to calculations to develop absolute emission measurements that can provide new tests of the non-LTE physics.

  17. The Galactic chemical evolution of oxygen inferred from 3D non-LTE spectral-line-formation calculations

    NASA Astrophysics Data System (ADS)

    Amarsi, A. M.; Asplund, M.; Collet, R.; Leenaarts, J.

    2015-11-01

    We revisit the Galactic chemical evolution of oxygen, addressing the systematic errors inherent in classical determinations of the oxygen abundance that arise from the use of one-dimensional (1D) hydrostatic model atmospheres and from the assumption of local thermodynamic equilibrium (LTE). We perform detailed 3D non-LTE radiative-transfer calculations for atomic oxygen lines across a grid of 3D hydrodynamic STAGGER model atmospheres for dwarfs and subgiants. We apply our grid of predicted line strengths of the [O I] 630 nm and O I 777 nm lines using accurate stellar parameters from the literature. We infer a steep decay in [O/Fe] for [Fe/H] ≳ -1.0, a plateau [O/Fe] ≈ 0.5 down to [Fe/H] ≈ -2.5, and an increasing trend for [Fe/H] ≲ -2.5. Our 3D non-LTE calculations yield overall concordant results from the two oxygen abundance diagnostics.

  18. Non-LTE line-blanketed model atmospheres of hot stars. 1: Hybrid complete linearization/accelerated lambda iteration method

    NASA Technical Reports Server (NTRS)

    Hubeny, I.; Lanz, T.

    1995-01-01

    A new munerical method for computing non-Local Thermodynamic Equilibrium (non-LTE) model stellar atmospheres is presented. The method, called the hybird complete linearization/accelerated lambda iretation (CL/ALI) method, combines advantages of both its constituents. Its rate of convergence is virtually as high as for the standard CL method, while the computer time per iteration is almost as low as for the standard ALI method. The method is formulated as the standard complete lineariation, the only difference being that the radiation intensity at selected frequency points is not explicity linearized; instead, it is treated by means of the ALI approach. The scheme offers a wide spectrum of options, ranging from the full CL to the full ALI method. We deonstrate that the method works optimally if the majority of frequency points are treated in the ALI mode, while the radiation intensity at a few (typically two to 30) frequency points is explicity linearized. We show how this method can be applied to calculate metal line-blanketed non-LTE model atmospheres, by using the idea of 'superlevels' and 'superlines' introduced originally by Anderson (1989). We calculate several illustrative models taking into accont several tens of thosands of lines of Fe III to Fe IV and show that the hybrid CL/ALI method provides a robust method for calculating non-LTE line-blanketed model atmospheres for a wide range of stellar parameters. The results for individual stellar types will be presented in subsequent papers in this series.

  19. CO2 non-LTE limb emissions in Mars' atmosphere as observed by OMEGA/Mars Express

    NASA Astrophysics Data System (ADS)

    Piccialli, A.; López-Valverde, M. A.; Määttänen, A.; González-Galindo, F.; Audouard, J.; Altieri, F.; Forget, F.; Drossart, P.; Gondet, B.; Bibring, J. P.

    2016-06-01

    We report on daytime limb observations of Mars upper atmosphere acquired by the OMEGA instrument on board the European spacecraft Mars Express. The strong emission observed at 4.3 μm is interpreted as due to CO2 fluorescence of solar radiation and is detected at a tangent altitude in between 60 and 110 km. The main value of OMEGA observations is that they provide simultaneously spectral information and good spatial sampling of the CO2 emission. In this study we analyzed 98 dayside limb observations spanning over more than 3 Martian years, with a very good latitudinal and longitudinal coverage. Thanks to the precise altitude sounding capabilities of OMEGA, we extracted vertical profiles of the non-local thermodynamic equilibrium (non-LTE) emission at each wavelength and we studied their dependence on several geophysical parameters, such as the solar illumination and the tangent altitude. The dependence of the non-LTE emission on solar zenith angle and altitude follows a similar behavior to that predicted by the non-LTE model. According to our non-LTE model, the tangent altitude of the peak of the CO2 emission varies with the thermal structure, but the pressure level where the peak of the emission is found remains constant at ˜0.03 ± 0.01 Pa, . This non-LTE model prediction has been corroborated by comparing SPICAM and OMEGA observations. We have shown that the seasonal variations of the altitude of constant pressure levels in SPICAM stellar occultation retrievals correlate well with the variations of the OMEGA peak emission altitudes, although the exact pressure level cannot be defined with the spectroscopy for the investigation of the characteristics of the atmosphere of Venus (SPICAM) nighttime data. Thus, observed changes in the altitude of the peak emission provide us information on the altitude of the 0.03 Pa pressure level. Since the pressure at a given altitude is dictated by the thermal structure below, the tangent altitude of the peak emission represents

  20. Import and visualization of clinical medical imagery into multiuser VR environments

    NASA Astrophysics Data System (ADS)

    Mehrle, Andreas H.; Freysinger, Wolfgang; Kikinis, Ron; Gunkel, Andreas; Kral, Florian

    2005-03-01

    The graphical representation of three-dimensional data obtained from tomographic imaging has been the central problem since this technology is available. Neither the representation as a set of two-dimensional slices nor the 2D projection of three-dimensional models yields satisfactory results. In this paper a way is outlined which permits the investigation of volumetric clinical data obtained from standard CT, MR, PET, SPECT or experimental very high resolution CT-scanners in a three dimensional environment within a few worksteps. Volumetric datasets are converted into surface data (segmentation process) using the 3D-Slicer software tool and saved as .vtk files and exported as a collection of primitives in any common file format (.iv, .pfb). Subsequently this files can be displayed and manipulated in the CAVE virtual reality center. The CAVE is a multiuser walkable virtual room consisting of several walls on which stereoscopic images are projected by rear panel beamers. Adequate tracking of the head position and separate image calculation for each eye yields a vivid impression for one or several users. With the use of a seperately tracked 6D joystick manipulations such as rotation, translation, zooming, decomposition or highlighting can be done intuitively. The usage of the CAVE technology opens new possibilities especially in surgical training ("hands-on-effect") and as an educational tool (availability of pathological data). Unlike concurring technologies the CAVE permits a walk-through into the virtual scene but preserves enough physical perception to allow interaction between multiple users, e.g. gestures and movements. By training in a virtual environment on one hand the learning process of students in complex anatomic findings may be improved considerably and on the other hand unaccustomed views such as the one through a microscope or endoscope can be trained in advance. The availability of low-cost PC based CAVE-like systems and the rapidly decreasing price

  1. Non-LTE spectral analysis and model constraints on SN 1993J

    NASA Technical Reports Server (NTRS)

    Baron, E.; Hauschildt, P. H.; Branch, D.; Austin, S.; Garnavich, P.; Ann, Hong Bae; Wagner, R. M.; Filippenko, A. V.; Matheson, T.; Liebert, James

    1995-01-01

    We present non-Local Thermodynamic Equilibrium (LTE) synthetic spectra for a time series of observations of SN 1993J obtained on 1993 March 30-31, April 7, April 13-15, and June 13 UT. The spectra are dominated by hydrogen Balmer lines; neutral helium lines, which have been nonthermally excited; and Fe II features. The density profile evolves from an extremely steep 'brick wall' structure with an equivalent power-law index of about 50 on March 30 to a more typical SN II profile with a power law index of about 10. The early spectra are well fitted by a solar composition of metals, although an enhanced abundance of helium is required in order to fit the neutral helium lines. By June 13, the photosphere has receded deep into the helium layer, although there appears to be a layer of hydrogen at higher velocity. The distance is estimated for each epoch. While consistent results are found for spectra obtained in the month of April, the spread in distances from March to June is quite large. Our value for April is mu = 28.0 +/- 0.3 mag, consistent with the recent Cepheid distance to the host galaxy M81. We also compare our results to other implementations of the expanding photosphere method.

  2. Non-LTE analysis of the Ofpe/WN9 star HDE 269227 (R84)

    SciTech Connect

    Schmutz, W.; Leitherer, C.; Hubeny, I.; Vogel, M.; Hamann, W.R. Space Telescope Science Institute, Baltimore, MD NASA, Goddard Space Flight Center, Greenbelt, MD High Altitude Observatory, Boulder, CO Zuerich, Eidgenoessische Technische Hochschule, Zurich Kiel, Universitaet )

    1991-05-01

    The paper presents the results of a spectral analysis of the Ofpe/WN9 star HD 269227 (R84), which assumes a spherically expanding atmosphere to find solutions for equations of radiative transfer. The spectra of hydrogen and helium were predicted with a non-LTE model. Six stellar parameters were determined for R84. The shape of the velocity law is empirically found, since it can be probed from the terminal velocity of the wind. The six stellar parameters are further employed in a hydrodynamic model where stellar wind is assumed to be directed by radiation pressure, duplicating the mass-loss rate and the terminal wind velocity. The velocity laws found by computation and analysis are found to agree, supporting the theory of radiation-driven stellar wind. R84 is surmised to be a post-red supergiant which lost half of its initial mass, possibly during the red-supergiant phase. This mass loss is also suggested by its spectroscopic similarity to S Doradus. 104 refs.

  3. Enabling Remote Health-Caring Utilizing IoT Concept over LTE-Femtocell Networks

    PubMed Central

    Hindia, M. N.; Rahman, T. A.; Ojukwu, H.; Hanafi, E. B.; Fattouh, A.

    2016-01-01

    As the enterprise of the “Internet of Things” is rapidly gaining widespread acceptance, sensors are being deployed in an unrestrained manner around the world to make efficient use of this new technological evolution. A recent survey has shown that sensor deployments over the past decade have increased significantly and has predicted an upsurge in the future growth rate. In health-care services, for instance, sensors are used as a key technology to enable Internet of Things oriented health-care monitoring systems. In this paper, we have proposed a two-stage fundamental approach to facilitate the implementation of such a system. In the first stage, sensors promptly gather together the particle measurements of an android application. Then, in the second stage, the collected data are sent over a Femto-LTE network following a new scheduling technique. The proposed scheduling strategy is used to send the data according to the application’s priority. The efficiency of the proposed technique is demonstrated by comparing it with that of well-known algorithms, namely, proportional fairness and exponential proportional fairness. PMID:27152423

  4. A novel LTE scheduling algorithm for green technology in smart grid.

    PubMed

    Hindia, Mohammad Nour; Reza, Ahmed Wasif; Noordin, Kamarul Ariffin; Chayon, Muhammad Hasibur Rashid

    2015-01-01

    Smart grid (SG) application is being used nowadays to meet the demand of increasing power consumption. SG application is considered as a perfect solution for combining renewable energy resources and electrical grid by means of creating a bidirectional communication channel between the two systems. In this paper, three SG applications applicable to renewable energy system, namely, distribution automation (DA), distributed energy system-storage (DER) and electrical vehicle (EV), are investigated in order to study their suitability in Long Term Evolution (LTE) network. To compensate the weakness in the existing scheduling algorithms, a novel bandwidth estimation and allocation technique and a new scheduling algorithm are proposed. The technique allocates available network resources based on application's priority, whereas the algorithm makes scheduling decision based on dynamic weighting factors of multi-criteria to satisfy the demands (delay, past average throughput and instantaneous transmission rate) of quality of service. Finally, the simulation results demonstrate that the proposed mechanism achieves higher throughput, lower delay and lower packet loss rate for DA and DER as well as provide a degree of service for EV. In terms of fairness, the proposed algorithm shows 3%, 7 % and 9% better performance compared to exponential rule (EXP-Rule), modified-largest weighted delay first (M-LWDF) and exponential/PF (EXP/PF), respectively. PMID:25830703

  5. Non-LTE sodium abundance in galactic thick- and thin-disk red giants

    NASA Astrophysics Data System (ADS)

    Alexeeva, S. A.; Pakhomov, Yu. V.; Mashonkina, L. I.

    2014-07-01

    The non-LTE sodium abundance has been determined from the Na I 6154 and 6161 Å lines for 38 thin-disk stars (15 of them are Ba II stars), 15 thick-disk stars, 13 Hercules-stream stars, and 13 stars that cannot be attributed neither to the thick Galactic disk nor to the thin one. The Na I model atom has been constructed using the most accurate present-day atomic data. For the Na I 6154 and 6161 Å lines, the non-LTEabundance corrections are from -0.06 to -0.24 dex, depending on the stellar parameters. No differences in [Na/Fe] abundance between the thick and thin disks have been detected; the derived ratios are close to the solar ones. The existence of a [Na/Fe] overabundance in the Ba II stars has been confirmed. The Hercules-stream stars exhibit nearly solar [Na/Fe] ratios. The results obtained can be used to test the sodium nucleosynthesis models.

  6. Enabling Remote Health-Caring Utilizing IoT Concept over LTE-Femtocell Networks.

    PubMed

    Hindia, M N; Rahman, T A; Ojukwu, H; Hanafi, E B; Fattouh, A

    2016-01-01

    As the enterprise of the "Internet of Things" is rapidly gaining widespread acceptance, sensors are being deployed in an unrestrained manner around the world to make efficient use of this new technological evolution. A recent survey has shown that sensor deployments over the past decade have increased significantly and has predicted an upsurge in the future growth rate. In health-care services, for instance, sensors are used as a key technology to enable Internet of Things oriented health-care monitoring systems. In this paper, we have proposed a two-stage fundamental approach to facilitate the implementation of such a system. In the first stage, sensors promptly gather together the particle measurements of an android application. Then, in the second stage, the collected data are sent over a Femto-LTE network following a new scheduling technique. The proposed scheduling strategy is used to send the data according to the application's priority. The efficiency of the proposed technique is demonstrated by comparing it with that of well-known algorithms, namely, proportional fairness and exponential proportional fairness. PMID:27152423

  7. A Novel LTE Scheduling Algorithm for Green Technology in Smart Grid

    PubMed Central

    Hindia, Mohammad Nour; Reza, Ahmed Wasif; Noordin, Kamarul Ariffin; Chayon, Muhammad Hasibur Rashid

    2015-01-01

    Smart grid (SG) application is being used nowadays to meet the demand of increasing power consumption. SG application is considered as a perfect solution for combining renewable energy resources and electrical grid by means of creating a bidirectional communication channel between the two systems. In this paper, three SG applications applicable to renewable energy system, namely, distribution automation (DA), distributed energy system-storage (DER) and electrical vehicle (EV), are investigated in order to study their suitability in Long Term Evolution (LTE) network. To compensate the weakness in the existing scheduling algorithms, a novel bandwidth estimation and allocation technique and a new scheduling algorithm are proposed. The technique allocates available network resources based on application’s priority, whereas the algorithm makes scheduling decision based on dynamic weighting factors of multi-criteria to satisfy the demands (delay, past average throughput and instantaneous transmission rate) of quality of service. Finally, the simulation results demonstrate that the proposed mechanism achieves higher throughput, lower delay and lower packet loss rate for DA and DER as well as provide a degree of service for EV. In terms of fairness, the proposed algorithm shows 3%, 7 % and 9% better performance compared to exponential rule (EXP-Rule), modified-largest weighted delay first (M-LWDF) and exponential/PF (EXP/PF), respectively. PMID:25830703

  8. Characterization of Non-LTE Gold Plasmas in Controlled Conditions with Finite Tr

    SciTech Connect

    Heeter, R F; Foord, M E; Fournier, K B; Froula, D H; MacKinnon, A J; May, M J; Schneider, M B; Young, B K F

    2003-08-29

    Understanding the charge state distribution of golf plasmas, especially in conditions far from local thermodynamic equilibrium (non-LTE conditions), is among the issues in ICF hohlraum physics research. Detailed models of these plasmas have historically disagreed by several charge states under a given set of conditions; simplified models in radiation-hydrodynamics codes disagree more. This impacts the accurate prediction of radiation coupling within the hohlraum. Nova laser data for uniform gold plasmas at T{sub e} = 2.2 and T{sub r} < 0.05 keV and additional data from plasmas inside hohlraums have not resolved all of the issues. Here they report experiments using the Omega laser to obtain data over a wider parameter space. Gold samples embedded in Be disks expand under direct laser heating to n{sub e} {approx} 10{sup 21} cm{sup -3} with T{sub e} from 1 to 3 keV. Some of the disks are placed within hohlraums, providing a finite radiation temperature T{sub r} {approx} 150 eV. Densities are measured by imaging of plasma expansion; temperatures by Thomson scattering and K-shell spectroscopy of co-mixed KCl tracers. Emission spectroscopy of Au 5-3 emission from 2.9-4.2 keV provides charge state distribution information. They summarize results to date and remaining issues.

  9. Andragogical Characteristics and Expectations of University of Hawai'i Adult Learners in a 3D Multi-User Virtual Environment

    ERIC Educational Resources Information Center

    Meeder, Rebecca L.

    2012-01-01

    The purpose of this study was to discover which andragogical characteristics and expectations of adult learners manifested themselves in the three-dimensional, multi-user virtual environment known as Second Life. This digital ethnographic study focused specifically on adult students within the University of Hawai'i Second Life group and their…

  10. The Spectral Signature of Accretion in Low-Mass Protostars: Observations and Non-LTE Modelling

    NASA Astrophysics Data System (ADS)

    Wiesemeyer, Helmut

    1997-06-01

    shocks (Li & McKee, 1996, ApJ 464, 373) are discussed. Most models are calculated by semi-analytical methods. The CS emission is severely affected by non-LTE effects in the subcritical envelope regions. Therefore, I developed a code to solve the excitation conditions in cylindrical symmetry, leaving off simplifying assumptions such as microturbulent approaches or the limiting case of a large velocity gradient. It is entirely possible to solve for the non-LTE radiative transfer problem with a classical ray-tracing approach: even for non-local coupling between radiation and matter, only part of a cloud has to be considered. Using a multivariate quadrature rule published by Steinacker et al. (1995, JQSRT), and second-order acceleration of convergence together with a modified convergence criterion (as proposed by Dickel & Auer, 1994, ApJ 437, 222), it has been possible to perform a parameter study considering the effects of inclination, rotation, and turbulence on the line profiles. As an example, a toroidal protostellar envelope, as seen in the CS lines, shows a red-shifted self-absorption feature if it is viewed from the edge. The feature disappears in case of a face-on orientation. -- Finally, I tried to describe the observations in terms of the above models. At present, it is not possible to rule out either of the (simplifying) scenarios considered. Nevertheless, some features in the line profiles are reproduced, using models that satisfy constraints inferred from various mass estimates. Characteristic scale-heights are deduced that allow for a comparison with the period of the regularly spaced globules.

  11. Calculation of emission and absorption spectra of LTE plasma by the STA (Super Transition Array) method

    SciTech Connect

    Bar-Shalon, A.; Oreg, J. . Nuclear Research Center-Negev); Goldstein, W.H. )

    1991-01-11

    Recent improvements in the Super Transition Array (STA) method for calculating Bound-Bound (BB) and Bound-Free (BF) emission and absorption spectra for LTE plasma are described and illustrated. The method accounts for all possible BB and BF radiative transitions in the plasma. Full detailed first order quantum relativistic treatment is used for calculating transition energies and probabilities. The enormous number of configurations are divided into sets of superconfigurations comprised of a collection of energetically grouped configurations. The contribution of the transition array between two superconfigurations to a specific one-electron transition is then represented by a Gaussian whose moments are calculated accurately using a technique that bypasses the necessity of direct summation over all the levels involved. The calculation of these moments involves the populations of the configurations given by their statistical weights and the Boltzmann factor. For each configuration within the super configuration we use zeroeth order energies in the Boltzmann factor corrected by a super configuration averaged first order term. The structure of the spectrum is increasingly revealed by splitting each STA into a number of smaller STAs. When the spectrum converges it describes the detailed UTA' structure, where each configuration-to-configuration array is represented by a separate Gaussian with first order energy in the Boltzmann factor. Convergence is reached with only a few thousand STAs, at most, which makes the calculations practical. It should be pointed out that in this treatment the STA moments are obtained by summing over all level-to-level transitions, rather than configuration-to-configuration average transitions. 4 refs., 9 figs.

  12. PORTA: A Massively Parallel Code for 3D Non-LTE Polarized Radiative Transfer

    NASA Astrophysics Data System (ADS)

    Štěpán, J.

    2014-10-01

    The interpretation of the Stokes profiles of the solar (stellar) spectral line radiation requires solving a non-LTE radiative transfer problem that can be very complex, especially when the main interest lies in modeling the linear polarization signals produced by scattering processes and their modification by the Hanle effect. One of the main difficulties is due to the fact that the plasma of a stellar atmosphere can be highly inhomogeneous and dynamic, which implies the need to solve the non-equilibrium problem of generation and transfer of polarized radiation in realistic three-dimensional stellar atmospheric models. Here we present PORTA, a computer program we have developed for solving, in three-dimensional (3D) models of stellar atmospheres, the problem of the generation and transfer of spectral line polarization taking into account anisotropic radiation pumping and the Hanle and Zeeman effects in multilevel atoms. The numerical method of solution is based on a highly convergent iterative algorithm, whose convergence rate is insensitive to the grid size, and on an accurate short-characteristics formal solver of the Stokes-vector transfer equation which uses monotonic Bezier interpolation. In addition to the iterative method and the 3D formal solver, another important feature of PORTA is a novel parallelization strategy suitable for taking advantage of massively parallel computers. Linear scaling of the solution with the number of processors allows to reduce the solution time by several orders of magnitude. We present useful benchmarks and a few illustrations of applications using a 3D model of the solar chromosphere resulting from MHD simulations. Finally, we present our conclusions with a view to future research. For more details see Štěpán & Trujillo Bueno (2013).

  13. New hybrid frequency reuse method for packet loss minimization in LTE network.

    PubMed

    Ali, Nora A; El-Dakroury, Mohamed A; El-Soudani, Magdi; ElSayed, Hany M; Daoud, Ramez M; Amer, Hassanein H

    2015-11-01

    This paper investigates the problem of inter-cell interference (ICI) in Long Term Evolution (LTE) mobile systems, which is one of the main problems that causes loss of packets between the base station and the mobile station. Recently, different frequency reuse methods, such as soft and fractional frequency reuse, have been introduced in order to mitigate this type of interference. In this paper, minimizing the packet loss between the base station and the mobile station is the main concern. Soft Frequency Reuse (SFR), which is the most popular frequency reuse method, is examined and the amount of packet loss is measured. In order to reduce packet loss, a new hybrid frequency reuse method is implemented. In this method, each cell occupies the same bandwidth of the SFR, but the total system bandwidth is greater than in SFR. This will provide the new method with a lot of new sub-carriers from the neighboring cells to reduce the ICI which represents a big problem in many applications and causes a lot of packets loss. It is found that the new hybrid frequency reuse method has noticeable improvement in the amount of packet loss compared to SFR method in the different frequency bands. Traffic congestion management in Intelligent Transportation system (ITS) is one of the important applications that is affected by the packet loss due to the large amount of traffic that is exchanged between the base station and the mobile node. Therefore, it is used as a studied application for the proposed frequency reuse method and the improvement in the amount of packet loss reached 49.4% in some frequency bands using the new hybrid frequency reuse method. PMID:26644933

  14. New hybrid frequency reuse method for packet loss minimization in LTE network

    PubMed Central

    Ali, Nora A.; El-Dakroury, Mohamed A.; El-Soudani, Magdi; ElSayed, Hany M.; Daoud, Ramez M.; Amer, Hassanein H.

    2014-01-01

    This paper investigates the problem of inter-cell interference (ICI) in Long Term Evolution (LTE) mobile systems, which is one of the main problems that causes loss of packets between the base station and the mobile station. Recently, different frequency reuse methods, such as soft and fractional frequency reuse, have been introduced in order to mitigate this type of interference. In this paper, minimizing the packet loss between the base station and the mobile station is the main concern. Soft Frequency Reuse (SFR), which is the most popular frequency reuse method, is examined and the amount of packet loss is measured. In order to reduce packet loss, a new hybrid frequency reuse method is implemented. In this method, each cell occupies the same bandwidth of the SFR, but the total system bandwidth is greater than in SFR. This will provide the new method with a lot of new sub-carriers from the neighboring cells to reduce the ICI which represents a big problem in many applications and causes a lot of packets loss. It is found that the new hybrid frequency reuse method has noticeable improvement in the amount of packet loss compared to SFR method in the different frequency bands. Traffic congestion management in Intelligent Transportation system (ITS) is one of the important applications that is affected by the packet loss due to the large amount of traffic that is exchanged between the base station and the mobile node. Therefore, it is used as a studied application for the proposed frequency reuse method and the improvement in the amount of packet loss reached 49.4% in some frequency bands using the new hybrid frequency reuse method. PMID:26644933

  15. Heavy-tailed distribution of the SSH Brute-force attack duration in a multi-user environment

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Kook; Kim, Sung-Jun; Park, Chan Yeol; Hong, Taeyoung; Chae, Huiseung

    2016-07-01

    Quite a number of cyber-attacks to be place against supercomputers that provide highperformance computing (HPC) services to public researcher. Particularly, although the secure shell protocol (SSH) brute-force attack is one of the traditional attack methods, it is still being used. Because stealth attacks that feign regular access may occur, they are even harder to detect. In this paper, we introduce methods to detect SSH brute-force attacks by analyzing the server's unsuccessful access logs and the firewall's drop events in a multi-user environment. Then, we analyze the durations of the SSH brute-force attacks that are detected by applying these methods. The results of an analysis of about 10 thousands attack source IP addresses show that the behaviors of abnormal users using SSH brute-force attacks are based on human dynamic characteristics of a typical heavy-tailed distribution.

  16. Real-time acquisition and data analysis of skeletal muscle contraction in a multi-user environment.

    PubMed

    Lieber, R L; Smith, D E; Campbell, R C; Hargens, A R

    1986-06-01

    A data acquisition system is described which acquires data from contracting skeletal muscle. The system is designed to run in a multi-user environment while acquiring contractile data in real-time. Time dedicated solely to laboratory experiments is thus eliminated. A menu-driver is included to allow users to enter experimental commands with or without command arguments. Error monitoring functions prevent operator errors from causing data loss. Data storage in both ASCII and binary formats maximizes file flexibility, readability and accessibility. Finally, an on-line tutorial and help facility is provided for user training. The system developed is applicable to any experimental environment involving data acquisition, storage and analysis. PMID:3637122

  17. Replica Analysis of Multiuser Detection for Code Division Multiple Access with M-Ary Phase-Shift Keying

    NASA Astrophysics Data System (ADS)

    Kato, Hiroyuki; Okada, Masato; Miyoshi, Seiji

    2013-07-01

    We analyze the performance of the maximizer of the posterior marginals (MPM) detector for code division multiple access (CDMA) multiuser detection with M-ary phase shift keying (M-ary PSK) in the large system limit by the replica method. The obtained theory agrees with computer simulation reasonably well. We also derive the theory in the case of the large M limit and discuss the dependence of the properties of M-ary PSK CDMA communication on M. We show that the waterfall phenomenon occurs for both the finite and infinite values of M. We also show that a value of M for which the decoded phase information on the original user symbol becomes minimum exists. Furthermore, we discuss the relationship between the theory based on the replica method and that based on self-consistent signal-to-noise analysis (SCSNA).

  18. Towards detecting methanol emission in low-mass protoplanetary discs with ALMA: the role of non-LTE excitation

    NASA Astrophysics Data System (ADS)

    Parfenov, S. Yu.; Semenov, D. A.; Sobolev, A. M.; Gray, M. D.

    2016-08-01

    The understanding of organic content of protoplanetary discs is one of the main goals of the planet formation studies. As an attempt to guide the observational searches for weak lines of complex species in discs, we modelled the (sub)millimetre spectrum of gaseous methanol (CH3OH), one of the simplest organic molecules, in the representative T Tauri system. We used 1+1D disc physical model coupled to the gas-grain ALCHEMIC chemical model with and without 2D-turbulent mixing. The computed CH3OH abundances along with the CH3OH scheme of energy levels of ground and excited torsional states were used to produce model spectra obtained with the non-local thermodynamic equilibrium (non-LTE) 3D line radiative transfer code LIME. We found that the modelled non-LTE intensities of the CH3OH lines can be lower by factor of >10-100 than those calculated under assumption of LTE. Though population inversion occurs in the model calculations for many (sub)millimetre transitions, it does not lead to the strong maser amplification and noticeably high line intensities. We identify the strongest CH3OH (sub)millimetre lines that could be searched for with the Atacama Large Millimeter Array (ALMA) in nearby discs. The two best candidates are the CH3OH 50 - 40A+ (241.791 GHz) and 5-1 - 4-1E (241.767 GHz) lines, which could possibly be detected with the ˜5σ signal-to-noise ratio after ˜3 h of integration with the full ALMA array.

  19. Non-LTE Kinetics Modeling and Experimental Investigation of VUV Emission from Low Temperature Nobel Gas Plasmas

    NASA Astrophysics Data System (ADS)

    Szilagyi, John; Parchamy, Homaira; Masnavi, Majid; Richardson, Martin; One Team

    2013-10-01

    The VUV light sources have applications in various scientific and engineering fields, such as semiconductor industry, nanometer processing, and photochemistry. A detailed multilevel non-LTE atomic model is developed to investigate emissivity and absorption properties of low temperature Nobel gas plasmas around 80 nm based on the Yb/Al multilayer mirrors. We will present the optimum regions for conversion efficiency of Nobel gas targets against target density and laser parameters by means of 1D hydrodynamic coupled to a developed population kinetics codes. We discuss in detailed predictions by comparing calculations to our experimental results.

  20. On magnetohydrodynamic thermal instabilities in magnetic flux tubes. [in plane parallel stellar atmosphere in LTE and hydrostatic equilibrium

    NASA Technical Reports Server (NTRS)

    Massaglia, S.; Ferrari, A.; Bodo, G.; Kalkofen, W.; Rosner, R.

    1985-01-01

    The stability of current-driven filamentary modes in magnetic flux tubes embedded in a plane-parallel atmosphere in LTE and in hydrostatic equilibrium is discussed. Within the tube, energy transport by radiation only is considered. The dominant contribution to the opacity is due to H- ions and H atoms (in the Paschen continuum). A region in the parameter space of the equilibrium configuration in which the instability is effective is delimited, and the relevance of this process for the formation of structured coronae in late-type stars and accretion disks is discussed.

  1. An energy-efficient SIMD DSP with multiple VLIW configurations and an advanced memory access unit for LTE-A modem LSIs

    NASA Astrophysics Data System (ADS)

    Tomono, Mitsuru; Ito, Makiko; Nomura, Yoshitaka; Mouri, Makoto; Hirose, Yoshio

    2015-12-01

    Energy efficiency is the most important factor in the design of wireless modem LSIs for mobile handset systems. We have developed an energy-efficient SIMD DSP for LTE-A modem LSIs. Our DSP has mainly two hardware features in order to reduce energy consumption. The first one is multiple VLIW configurations to minimize accesses to instruction memories. The second one is an advanced memory access unit to realize complex memory accesses required for wireless baseband processing. With these features, performance of our DSP is about 1.7 times faster than a base DSP on average for standard LTE-A Libraries. Our DSP achieves about 20% improvement in energy efficiency compared to a base DSP for LTE-A modem LSIs.

  2. A multi-mode multi-band RF receiver front-end for a TD-SCDMA/LTE/LTE-advanced in 0.18-μm CMOS process

    NASA Astrophysics Data System (ADS)

    Rui, Guo; Haiying, Zhang

    2012-09-01

    A fully integrated multi-mode multi-band directed-conversion radio frequency (RF) receiver front-end for a TD-SCDMA/LTE/LTE-advanced is presented. The front-end employs direct-conversion design, and consists of two differential tunable low noise amplifiers (LNA), a quadrature mixer, and two intermediate frequency (IF) amplifiers. The two independent tunable LNAs are used to cover all the four frequency bands, achieving sufficient low noise and high gain performance with low power consumption. Switched capacitor arrays perform a resonant frequency point calibration for the LNAs. The two LNAs are combined at the driver stage of the mixer, which employs a folded double balanced Gilbert structure, and utilizes PMOS transistors as local oscillator (LO) switches to reduce flicker noise. The front-end has three gain modes to obtain a higher dynamic range. Frequency band selection and mode of configuration is realized by an on-chip serial peripheral interface (SPI) module. The front-end is fabricated in a TSMC 0.18-μm RF CMOS process and occupies an area of 1.3 mm2. The measured double-sideband (DSB) noise figure is below 3.5 dB and the conversion gain is over 43 dB at all of the frequency bands. The total current consumption is 31 mA from a 1.8-V supply.

  3. Non-LTE spectral models for the gaseous debris-disk component of Ton 345

    NASA Astrophysics Data System (ADS)

    Hartmann, S.; Nagel, T.; Rauch, T.; Werner, K.

    2014-11-01

    Context. For a fraction of single white dwarfs with debris disks, an additional gaseous disk was discovered. Both dust and gas are thought to be created by the disruption of planetary bodies. Aims: The composition of the extrasolar planetary material can directly be analyzed in the gaseous disk component, and the disk dynamics might be accessible by investigating the temporal behavior of the Ca ii infrared emission triplet, hallmark of the gas disk. Methods: We obtained new optical spectra for the first helium-dominated white dwarf for which a gas disk was discovered (Ton 345) and modeled the non-LTE spectra of viscous gas disks composed of carbon, oxygen, magnesium, silicon, sulfur, and calcium with chemical abundances typical for solar system asteroids. Iron and its possible line-blanketing effects on the model structure and spectral energy distribution was still neglected. A set of models with different radii, effective temperatures, and surface densities as well as chondritic and bulk-Earth abundances was computed and compared with the observed line profiles of the Ca ii infrared triplet. Results: Our models suggest that the Ca ii emission stems from a rather narrow gas ring with a radial extent of R = 0.44-0.94 R⊙, a uniform surface density Σ = 0.3 g cm-2, and an effective temperature of Teff ≈ 6000 K. The often assumed chemical mixtures derived from photospheric abundances in polluted white dwarfs - similar to a chondritic or bulk-Earth composition - produce unobserved emission lines in the model and therefore have to be altered. We do not detect any line-profile variability on timescales of hours, but we confirm the long-term trend over the past decade for the red-blue asymmetry of the double-peaked lines. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck-Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).

  4. On the definition of adapted audio/video profiles for high-quality video calling services over LTE/4G

    NASA Astrophysics Data System (ADS)

    Ndiaye, Maty; Quinquis, Catherine; Larabi, Mohamed Chaker; Le Lay, Gwenael; Saadane, Hakim; Perrine, Clency

    2014-01-01

    During the last decade, the important advances and widespread availability of mobile technology (operating systems, GPUs, terminal resolution and so on) have encouraged a fast development of voice and video services like video-calling. While multimedia services have largely grown on mobile devices, the generated increase of data consumption is leading to the saturation of mobile networks. In order to provide data with high bit-rates and maintain performance as close as possible to traditional networks, the 3GPP (The 3rd Generation Partnership Project) worked on a high performance standard for mobile called Long Term Evolution (LTE). In this paper, we aim at expressing recommendations related to audio and video media profiles (selection of audio and video codecs, bit-rates, frame-rates, audio and video formats) for a typical video-calling services held over LTE/4G mobile networks. These profiles are defined according to targeted devices (smartphones, tablets), so as to ensure the best possible quality of experience (QoE). Obtained results indicate that for a CIF format (352 x 288 pixels) which is usually used for smartphones, the VP8 codec provides a better image quality than the H.264 codec for low bitrates (from 128 to 384 kbps). However sequences with high motion, H.264 in slow mode is preferred. Regarding audio, better results are globally achieved using wideband codecs offering good quality except for opus codec (at 12.2 kbps).

  5. Printed Notched Antenna with Long Meandered Line for Eight-Band LTE/GSM/UMTS Wireless USB Dongle Operation

    NASA Astrophysics Data System (ADS)

    Zhang, Y. H.; Sun, S. C.; Ban, Y. L.; Tang, X. H.

    2016-03-01

    This paper presents a planar notched antenna with a long meandered line for wireless USB dongle applications. The printed notched structure is used as additional resonators to generate multiple bands operation for covering GSM1800/1900/UMTS2100/LTE2300/2500 bands. In addition, with the help of the long meandered line via hole to ground, a lower resonant mode is sufficiently generated at around 770 MHz and forms a wider lower operating bandwidth (LTE700/GSM850/900). Briefly printed on a 0.8 mm thick FR4 dielectric substrate of size 20×70 mm² and electrically connected (via hole) to the ground plane of the USB dongle, the proposed antenna can provide a wide operating bandwidth (3:1 VSWR) of larger than 120 % centered at 2,000 MHz, allowing it to cover 698-960 and 1,710-2,690 MHz bands. The proposed antenna also can be attached to laptop computer by the USB interface. Detailed design considerations of the proposed antenna are described, and obtained experimental and simulation results are also presented and discussed in this paper.

  6. A wide-band low phase noise LC-tuned VCO with constant KVCO/ωosc for LTE PLL

    NASA Astrophysics Data System (ADS)

    Jiwei, Huang; Zhigong, Wang; Kuili, Li; Zhengping, Li; Yongping, Wang

    2012-02-01

    A wideband LC-tuned voltage-controlled oscillator (LC-VCO) applied in LTE PLL frequency synthesizers with constant KVCO/ωosc is described. In order to minimize the loop bandwidth variations of PLL, a varactor array is proposed, which consists of a series of differential variable capacitor pairs and a series of single-pole double-throw (SPDT) switches to connect Vtune or VDD. The switches are controlled by switching bits. With this scheme, the ratio of KV = ∂Cvar/∂Vtune and the capacitance value of the capacitor array maintains relatively constant; furthermore, the loop bandwidth of the PLL fluctuation is suppressed. The 3.2-4.6-GHz VCO for multi-band LTE PLL is fabricated in a 0.13-μm RF-CMOS process. The VCO exhibits a maximum variation of KVCO/ωosc of only ±4%. The VCO also exhibits a low phase-noise of-124 dBc/Hz at a 1-MHz offset frequency and a low current consumption of 18.0 mA with a 1.2-V power supply.

  7. A Non-LTE Study of Silicon Abundances in Giant Stars from the Si I Infrared Lines in the zJ-Band

    NASA Astrophysics Data System (ADS)

    Tan, Kefeng; Shi, Jianrong; Takada-Hidai, Masahide; Takeda, Yoichi; Zhao, Gang

    2016-05-01

    We investigate the feasibility of Si i infrared (IR) lines as Si abundance indicators for giant stars. We find that Si abundances obtained from the Si i IR lines based on the local thermodynamic equilibrium (LTE) analysis show large line-to-line scatter (mean value of 0.13 dex), and are higher than those from the optical lines. However, when non-LTE effects are taken into account, the line-to-line scatter reduces significantly (mean value of 0.06 dex), and the Si abundances are consistent with those from the optical lines. The typical average non-LTE correction of [Si/Fe] for our sample stars is about ‑0.35 dex. Our results demonstrate that the Si i IR lines could be reliable abundance indicators, provided that the non-LTE effects are properly taken into account. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan; based on observations made with ESO telescopes at the La Silla Paranal Observatory under programme IDs 266.D-5655(A) and 084.D-0912(A); based on observations carried out at the National Astronomical Observatories (Xinglong, China).

  8. Distributed microscopy: toward a 3D computer-graphic-based multiuser microscopic manipulation, imaging, and measurement system

    NASA Astrophysics Data System (ADS)

    Sulzmann, Armin; Carlier, Jerome; Jacot, Jacques

    1996-10-01

    The aim of this project is to telecontrol the movements in 3D-space of a microscope in order to manipulate and measure microsystems or micro parts aided by multi-user virtual reality (VR) environments. Presently microsystems are gaining in interest. Microsystems are small, independent modules, incorporating various functions, such as electronic, micro mechanical, data processing, optical, chemical, medical and biological functions. Though improving the manufacturing technologies, the measurement of the small structures to insure the quality of the process is a key information for the development. So far to measure the micro structures strong microscopes are needed. The use of highly magnifying computerized microscopes is expensive. To insure high quality measurements and distribute the acquired information to multi-user our proposed system is divided into three parts: the virtual reality microscopic environment (VRME)-based user-interface on a SGI workstation to prepare the manipulations and measurements. Secondly the computerized light microscope with the vision system inspecting the scene and getting the images of the specimen. Newly developed vision algorithms are used to analyze micro structures in the scene corresponding to the known a priori model. This vision is extracting position and shape of the objects and then transmitted as feedback to the user of the VRME-system to update his virtual environment. The internet demon is the third part of the system and distributes the information about the position of the micro structures, their shape and the images to the connected users who themselves may interact with the microscope (turn and displace the specimen on the back of a moving platform, or adding their structures to the scene and compare). The key idea behind our project VRME is to use the intuitiveness and the 3D visualization of VR environments coupled with a vision system to perform measurements of micro structures at a high accuracy. The direct

  9. A Novel Iterative Scheme for the Very Fast and Accurate Solution of Non-LTE Radiative Transfer Problems

    NASA Astrophysics Data System (ADS)

    Trujillo Bueno, J.; Fabiani Bendicho, P.

    1995-12-01

    Iterative schemes based on Gauss-Seidel (G-S) and optimal successive over-relaxation (SOR) iteration are shown to provide a dramatic increase in the speed with which non-LTE radiation transfer (RT) problems can be solved. The convergence rates of these new RT methods are identical to those of upper triangular nonlocal approximate operator splitting techniques, but the computing time per iteration and the memory requirements are similar to those of a local operator splitting method. In addition to these properties, both methods are particularly suitable for multidimensional geometry, since they neither require the actual construction of nonlocal approximate operators nor the application of any matrix inversion procedure. Compared with the currently used Jacobi technique, which is based on the optimal local approximate operator (see Olson, Auer, & Buchler 1986), the G-S method presented here is faster by a factor 2. It gives excellent smoothing of the high-frequency error components, which makes it the iterative scheme of choice for multigrid radiative transfer. This G-S method can also be suitably combined with standard acceleration techniques to achieve even higher performance. Although the convergence rate of the optimal SOR scheme developed here for solving non-LTE RT problems is much higher than G-S, the computing time per iteration is also minimal, i.e., virtually identical to that of a local operator splitting method. While the conventional optimal local operator scheme provides the converged solution after a total CPU time (measured in arbitrary units) approximately equal to the number n of points per decade of optical depth, the time needed by this new method based on the optimal SOR iterations is only √n/2√2. This method is competitive with those that result from combining the above-mentioned Jacobi and G-S schemes with the best acceleration techniques. Contrary to what happens with the local operator splitting strategy currently in use, these novel

  10. International Microgravity Plasma Facility IMPF: A Multi-User Modular Research Facility for Complex Plasma Research on ISS

    NASA Astrophysics Data System (ADS)

    Seurig, R.; Burfeindt, J.; Castegini, R.; Griethe, W.; Hofmann, P.

    2002-01-01

    On March 03, 2001, the PKE-Nefedov plasma experiment was successfully put into operation on board ISS. This complex plasma experiment is the predecessor for the semi-autonomous multi-user facility IMPF (International Microgravity Plasma Facility) to be flown in 2006 with an expected operational lifetime of 10 years. IMPF is envisioned to be an international research facility for investigators in the field of multi-component plasmas containing ions, electrons, and charged microparticles. This research filed is often referred to as "complex plasmas". The actual location of IMPF on ISS is not decided yet; potential infrastructure under consideration are EXPRESS Rack, Standard Interface Rack SIR, European Drawer Rack EDR, or a to be designed custom rack infrastructure on the Russian Segment. The actual development status of the DLR funded Pre-phase B Study for IMPF will be presented. For this phase, IMPF was assumed to be integrated in an EXPRESS Rack requiring four middeck lockers with two 4-PU ISIS drawers for accommodation. Technical and operational challenges, like a 240 Mbytes/sec continuous experimental data stream for 60 minutes, will be addressed. The project was funded by the German Space Agency (DLR) and was performed in close cooperation with scientists from the Max-Planck-Institute for Extraterrestical Physics in Munich, Germany.

  11. Investigating source water Cryptosporidium concentration, species and infectivity rates during rainfall-runoff in a multi-use catchment.

    PubMed

    Swaffer, Brooke A; Vial, Hayley M; King, Brendon J; Daly, Robert; Frizenschaf, Jacqueline; Monis, Paul T

    2014-12-15

    Protozoan pathogens present a significant human health concern, and prevention of contamination into potable networks remains a key focus for drinking water providers. Here, we monitored the change in Cryptosporidium concentration in source water during high flow events in a multi-use catchment. Furthermore, we investigated the diversity of Cryptosporidium species/genotypes present in the source water, and delivered an oocyst infectivity fraction. There was a positive and significant correlation between Cryptosporidium concentration and flow (ρ = 0.756) and turbidity (ρ = 0.631) for all rainfall-runoff events, despite variable source water pathogen concentrations. Cell culture assays measured oocyst infectivity and suggested an overall source water infectious fraction of 3.1%. No infectious Cryptosporidium parvum or Cryptosporidium hominis were detected, although molecular testing detected C. parvum in 7% of the samples analysed using PCR-based molecular techniques. Twelve Cryptosporidium species/genotypes were identified using molecular techniques, and were reflective of the host animals typically found in remnant vegetation and agricultural areas. The inclusion of molecular approaches to identify Cryptosporidium species and genotypes highlighted the diversity of pathogens in water, which originated from various sources across the catchment. We suggest this mixing of runoff water from a range of landuses containing diverse Cryptosporidium hosts is a key explanation for the often-cited difficulty forming strong pathogen-indicator relationships. PMID:25306487

  12. The Applications of Decision-Level Data Fusion Techniques in the Field of Multiuser Detection for DS-UWB Systems

    PubMed Central

    Gu, Yebo; Yang, Minglei; Shi, Zhenguo; Wu, Zhilu

    2015-01-01

    In this paper, the decision-level data fusion techniques are extended to the multiuser detection (MUD) field. Then two novel MUD algorithms, that is the chairman arbitrating decision-level fusion criterion (CA-DFC) based MUD algorithm and the veto logic decision-level fusion criterion (VL-DFC) based MUD algorithm, are proposed for DS-UWB communication systems. In CA-DFC based method, the chairman can make his arbitration among the preliminary decisions from sub-optimal detectors by his own rule. In the VL-DFC based method, the undetermined bits in these preliminary decisions are considered to construct a simplified solution space, and then the chairman can make his final decision within this space. Simulation results demonstrate that the performances of CA-DFC and VL-DFC based MUD algorithms are superior to those of other sub-optimal MUD algorithms, and even close to that of OMD. Moreover, both of these proposed algorithms have lower computational complexity than OMD, which reveals their efficiency. Compared with CA-DFC, VL-DFC based algorithm achieves a little improvement in its performance, at the cost of the increment in its computational complexity. Thus, they can be applied to different practical situations. PMID:26404273

  13. The Viking viewer for connectomics: scalable multi-user annotation and summarization of large volume data sets.

    PubMed

    Anderson, J R; Mohammed, S; Grimm, B; Jones, B W; Koshevoy, P; Tasdizen, T; Whitaker, R; Marc, R E

    2011-01-01

    Modern microscope automation permits the collection of vast amounts of continuous anatomical imagery in both two and three dimensions. These large data sets present significant challenges for data storage, access, viewing, annotation and analysis. The cost and overhead of collecting and storing the data can be extremely high. Large data sets quickly exceed an individual's capability for timely analysis and present challenges in efficiently applying transforms, if needed. Finally annotated anatomical data sets can represent a significant investment of resources and should be easily accessible to the scientific community. The Viking application was our solution created to view and annotate a 16.5 TB ultrastructural retinal connectome volume and we demonstrate its utility in reconstructing neural networks for a distinctive retinal amacrine cell class. Viking has several key features. (1) It works over the internet using HTTP and supports many concurrent users limited only by hardware. (2) It supports a multi-user, collaborative annotation strategy. (3) It cleanly demarcates viewing and analysis from data collection and hosting. (4) It is capable of applying transformations in real-time. (5) It has an easily extensible user interface, allowing addition of specialized modules without rewriting the viewer. PMID:21118201

  14. 1x2 Array of U-Slotted Rectangular Patch Antennas for HighSpeed LTE Mobile Networks

    NASA Astrophysics Data System (ADS)

    Daud, P.; H, Sri.; Mahmudin, D.; Estu, T. T.; Fathnan, A. A.; Wijayanto, Y. N.; Armi, N.

    2016-01-01

    Microstrip antenna is a shaped thin board of antenna and capable for working at high frequencies. Microstrip antenna has a pattern strip shape in a various form, one of which is a rectangular shape. Microstrip antennas have some shortcomings which have narrow bandwidth and small gain, to cover the shortfall, the antenna is made using an array to increase the gain and u - slot to widen the bandwidth. In this paper will discuss the results of the antenna simulation using Ansoft HFSS software applications and their compliance with specifications designed antenna. In this issues we analysis the results of the design and simulation microstrip antenna at a frequency of 2.6 - 2.7 GHz for LTE applications

  15. A non-LTE study of silicon line formation in early-type main-sequence atmospheres.

    NASA Technical Reports Server (NTRS)

    Kamp, L. W.

    1973-01-01

    We have computed populations of 16 levels of Si III-V and radiation fields in all connecting transitions; in particular the first six Si III triplet levels, including the 4553 line, and the first six Si IV levels including 4089. The computations were done for four non-LTE H-He model atmospheres, provided by Auer and Mihalas. Estimates of corresponding MK types are B1.5 V, B0.5 V, O9 V, and O6. Solutions were obtained by iterating the linearized equations of radiative transfer and statistical equilibrium, except that for less important lines an approximate equivalent two-level atom treatment was used. Continuous opacities of C, N, O, and Ne were included. All abundances were solar values.

  16. Iterative Methods for the Non-LTE Transfer of Polarized Radiation: Resonance Line Polarization in One-dimensional Atmospheres

    NASA Astrophysics Data System (ADS)

    Trujillo Bueno, Javier; Manso Sainz, Rafael

    1999-05-01

    This paper shows how to generalize to non-LTE polarization transfer some operator splitting methods that were originally developed for solving unpolarized transfer problems. These are the Jacobi-based accelerated Λ-iteration (ALI) method of Olson, Auer, & Buchler and the iterative schemes based on Gauss-Seidel and successive overrelaxation (SOR) iteration of Trujillo Bueno and Fabiani Bendicho. The theoretical framework chosen for the formulation of polarization transfer problems is the quantum electrodynamics (QED) theory of Landi Degl'Innocenti, which specifies the excitation state of the atoms in terms of the irreducible tensor components of the atomic density matrix. This first paper establishes the grounds of our numerical approach to non-LTE polarization transfer by concentrating on the standard case of scattering line polarization in a gas of two-level atoms, including the Hanle effect due to a weak microturbulent and isotropic magnetic field. We begin demonstrating that the well-known Λ-iteration method leads to the self-consistent solution of this type of problem if one initializes using the ``exact'' solution corresponding to the unpolarized case. We show then how the above-mentioned splitting methods can be easily derived from this simple Λ-iteration scheme. We show that our SOR method is 10 times faster than the Jacobi-based ALI method, while our implementation of the Gauss-Seidel method is 4 times faster. These iterative schemes lead to the self-consistent solution independently of the chosen initialization. The convergence rate of these iterative methods is very high; they do not require either the construction or the inversion of any matrix, and the computing time per iteration is similar to that of the Λ-iteration method.

  17. A hardware and software architecture to deal with multimodal and collaborative interactions in multiuser virtual reality environments

    NASA Astrophysics Data System (ADS)

    Martin, P.; Tseu, A.; Férey, N.; Touraine, D.; Bourdot, P.

    2014-02-01

    Most advanced immersive devices provide collaborative environment within several users have their distinct head-tracked stereoscopic point of view. Combining with common used interactive features such as voice and gesture recognition, 3D mouse, haptic feedback, and spatialized audio rendering, these environments should faithfully reproduce a real context. However, even if many studies have been carried out on multimodal systems, we are far to definitively solve the issue of multimodal fusion, which consists in merging multimodal events coming from users and devices, into interpretable commands performed by the application. Multimodality and collaboration was often studied separately, despite of the fact that these two aspects share interesting similarities. We discuss how we address this problem, thought the design and implementation of a supervisor that is able to deal with both multimodal fusion and collaborative aspects. The aim of this supervisor is to ensure the merge of user's input from virtual reality devices in order to control immersive multi-user applications. We deal with this problem according to a practical point of view, because the main requirements of this supervisor was defined according to a industrial task proposed by our automotive partner, that as to be performed with multimodal and collaborative interactions in a co-located multi-user environment. In this task, two co-located workers of a virtual assembly chain has to cooperate to insert a seat into the bodywork of a car, using haptic devices to feel collision and to manipulate objects, combining speech recognition and two hands gesture recognition as multimodal instructions. Besides the architectural aspect of this supervisor, we described how we ensure the modularity of our solution that could apply on different virtual reality platforms, interactive contexts and virtual contents. A virtual context observer included in this supervisor in was especially designed to be independent to the

  18. Patterns of Lynx Predation at the Interface between Protected Areas and Multi-Use Landscapes in Central Europe.

    PubMed

    Belotti, Elisa; Weder, Nicole; Bufka, Luděk; Kaldhusdal, Arne; Küchenhoff, Helmut; Seibold, Heidi; Woelfing, Benno; Heurich, Marco

    2015-01-01

    In Central Europe, protected areas are too small to ensure survival of populations of large carnivores. In the surrounding areas, these species are often persecuted due to competition with game hunters. Therefore, understanding how predation intensity varies spatio-temporally across areas with different levels of protection is fundamental. We investigated the predation patterns of Eurasian lynx (Lynx lynx) on roe deer (Capreolus capreolus) and red deer (Cervus elaphus) in both protected areas and multi-use landscapes of the Bohemian Forest Ecosystem. Based on 359 roe and red deer killed by 10 GPS-collared lynx, we calculated the species-specific annual kill rates and tested for effects of season and lynx age, sex and reproductive status. Because roe and red deer in the study area concentrate in unprotected lowlands during winter, we modeled spatial distribution of kills separately for summer and winter and calculated-the probability of a deer killed by lynx and-the expected number of kills for areas with different levels of protection. Significantly more roe deer (46.05-74.71/year/individual lynx) were killed than red deer (1.57-9.63/year/individual lynx), more deer were killed in winter than in summer, and lynx family groups had higher annual kill rates than adult male, single adult female and subadult female lynx. In winter the probability of a deer killed and the expected number of kills were higher outside the most protected part of the study area than inside; in summer, this probability did not differ between areas, and the expected number of kills was slightly larger inside than outside the most protected part of the study area. This indicates that the intensity of lynx predation in the unprotected part of the Bohemian Forest Ecosystem increases in winter, thus mitigation of conflicts in these areas should be included as a priority in the lynx conservation strategy. PMID:26379142

  19. Patterns of Lynx Predation at the Interface between Protected Areas and Multi-Use Landscapes in Central Europe

    PubMed Central

    Belotti, Elisa; Weder, Nicole; Bufka, Luděk; Kaldhusdal, Arne; Küchenhoff, Helmut; Seibold, Heidi; Woelfing, Benno; Heurich, Marco

    2015-01-01

    In Central Europe, protected areas are too small to ensure survival of populations of large carnivores. In the surrounding areas, these species are often persecuted due to competition with game hunters. Therefore, understanding how predation intensity varies spatio-temporally across areas with different levels of protection is fundamental. We investigated the predation patterns of Eurasian lynx (Lynx lynx) on roe deer (Capreolus capreolus) and red deer (Cervus elaphus) in both protected areas and multi-use landscapes of the Bohemian Forest Ecosystem. Based on 359 roe and red deer killed by 10 GPS-collared lynx, we calculated the species-specific annual kill rates and tested for effects of season and lynx age, sex and reproductive status. Because roe and red deer in the study area concentrate in unprotected lowlands during winter, we modeled spatial distribution of kills separately for summer and winter and calculated-the probability of a deer killed by lynx and-the expected number of kills for areas with different levels of protection. Significantly more roe deer (46.05–74.71/year/individual lynx) were killed than red deer (1.57–9.63/year/individual lynx), more deer were killed in winter than in summer, and lynx family groups had higher annual kill rates than adult male, single adult female and subadult female lynx. In winter the probability of a deer killed and the expected number of kills were higher outside the most protected part of the study area than inside; in summer, this probability did not differ between areas, and the expected number of kills was slightly larger inside than outside the most protected part of the study area. This indicates that the intensity of lynx predation in the unprotected part of the Bohemian Forest Ecosystem increases in winter, thus mitigation of conflicts in these areas should be included as a priority in the lynx conservation strategy. PMID:26379142

  20. A Web-based Multi-user Interactive Visualization System For Large-Scale Computing Using Google Web Toolkit Technology

    NASA Astrophysics Data System (ADS)

    Weiss, R. M.; McLane, J. C.; Yuen, D. A.; Wang, S.

    2009-12-01

    We have created a web-based, interactive system for multi-user collaborative visualization of large data sets (on the order of terabytes) that allows users in geographically disparate locations to simultaneous and collectively visualize large data sets over the Internet. By leveraging asynchronous java and XML (AJAX) web development paradigms via the Google Web Toolkit (http://code.google.com/webtoolkit/), we are able to provide remote, web-based users a web portal to LCSE's (http://www.lcse.umn.edu) large-scale interactive visualization system already in place at the University of Minnesota that provides high resolution visualizations to the order of 15 million pixels by Megan Damon. In the current version of our software, we have implemented a new, highly extensible back-end framework built around HTTP "server push" technology to provide a rich collaborative environment and a smooth end-user experience. Furthermore, the web application is accessible via a variety of devices including netbooks, iPhones, and other web- and javascript-enabled cell phones. New features in the current version include: the ability for (1) users to launch multiple visualizations, (2) a user to invite one or more other users to view their visualization in real-time (multiple observers), (3) users to delegate control aspects of the visualization to others (multiple controllers) , and (4) engage in collaborative chat and instant messaging with other users within the user interface of the web application. We will explain choices made regarding implementation, overall system architecture and method of operation, and the benefits of an extensible, modular design. We will also discuss future goals, features, and our plans for increasing scalability of the system which includes a discussion of the benefits potentially afforded us by a migration of server-side components to the Google Application Engine (http://code.google.com/appengine/).

  1. Oracle and the end-user: Practical implementation of applications in a multi-user, multi-platform environment

    SciTech Connect

    Not Available

    1992-07-01

    This presentation will describe methods used to develop a standard user-interface to ORACLE applications, to train users, and document these systems in a diverse multi-user, multi-platform environment. Implementation and documentation of applications and training of users can be difficult when the end-users have diverse levels of computer proficiency and work with a multiple array of hardware platforms. We will discuss common problems encountered in such an environment and the approaches used to solve them. The Advanced Photon Source at Argonne National Laboratory has over 300 users, using a variety of hardware: SUN workstations, Machintoshes, PCs running MS-Windows, VAXstations, DECstations, and a variety of terminal types. The perfect scenario would be to allow everyone to access the database using a particular workstation environment, or if using a terminal, access the database using the standard function keys. For example, a Macintosh user could use a true graphics version of SQL*FORMS; likewise a SUN workstation user. We are in the process of evaluating the use of utilities such as bit-mapped versions of SQL*FORMS for SUNs and Macintoshes, and intend to continue work in that direction. However, there are still some issues to be resolved, both technical and financial, before client-server technology becomes a realistic alternative in our mixed environment. This presentation will have two components. Part 1 will address some technical issues concerned with providing a standard user interface. Part 2 will deal with administrative issues; specifically documentation, user training, and communications between users and developers.

  2. Oracle and the end-user: Practical implementation of applications in a multi-user, multi-platform environment

    SciTech Connect

    Not Available

    1992-01-01

    This presentation will describe methods used to develop a standard user-interface to ORACLE applications, to train users, and document these systems in a diverse multi-user, multi-platform environment. Implementation and documentation of applications and training of users can be difficult when the end-users have diverse levels of computer proficiency and work with a multiple array of hardware platforms. We will discuss common problems encountered in such an environment and the approaches used to solve them. The Advanced Photon Source at Argonne National Laboratory has over 300 users, using a variety of hardware: SUN workstations, Machintoshes, PCs running MS-Windows, VAXstations, DECstations, and a variety of terminal types. The perfect scenario would be to allow everyone to access the database using a particular workstation environment, or if using a terminal, access the database using the standard function keys. For example, a Macintosh user could use a true graphics version of SQL*FORMS; likewise a SUN workstation user. We are in the process of evaluating the use of utilities such as bit-mapped versions of SQL*FORMS for SUNs and Macintoshes, and intend to continue work in that direction. However, there are still some issues to be resolved, both technical and financial, before client-server technology becomes a realistic alternative in our mixed environment. This presentation will have two components. Part 1 will address some technical issues concerned with providing a standard user interface. Part 2 will deal with administrative issues; specifically documentation, user training, and communications between users and developers.

  3. Non-LTE effects on the ionization equilibrium of Fe I/Fe II: Application to the red giants of Carina dSph Galaxy

    NASA Astrophysics Data System (ADS)

    Merle, T.; Fabrizio, M.; Thévenin, F.; Nonino, M.; Bono, G.

    2012-12-01

    In the context of the Carina Project, we re-analyze the iron abundances of 44 red giants of the Carina dSph galaxy to derive its metallicity distribution function. The abundance analyses were performed with the LTE spectrum synthesis fitting method using ESO/VLT high resolution spectra. Using {Fe I} lines, we obtained stellar metallicities of ˜0.1 dex lower than using {Fe II} lines. This discrepancy is classically interpreted as an error on the surface gravity (based on photometry and evolutionary tracks) which is removed by changing gravity until {Fe I} abundances match {Fe II} ones. However, the NLTE mechanism of over-ionization regarding LTE can also explain this discrepancy in giant stars. To support this idea, we performed NLTE computations with a {Fe I}/II model atom and show that this discrepancy is well reproduced. NLTE computations also highlight large discrepancies in individual lines of {Fe I} and {Fe II}.

  4. Observations of the He I 10830 A line in main-sequence O9-B6 stars and comparison with non-LTE predictions

    NASA Astrophysics Data System (ADS)

    Lennon, D. J.; Dufton, P. L.

    1989-11-01

    New high resolution CCD observations of the He I 10830 A line in O9-B6 main-sequence stars are presented and compared with previous non-LTE model atmosphere calculations. While good qualitative agreement with the results of Auer and Mihalas (1973) is found, the theoretical results tend to overestimate the line strength. This is particularly serious at the earliest spectral types where the observations imply that the line is either very weak in absorption or (for Tau Sco) very weak in emission. This line provides a stringent test of the validity of the model atmosphere calculations due to (1) its high sensitivity to non-LTE effects, (2) the transition between low lying levels leading to compact model atom and (3) reliable atomic data available for most processes involving helium atoms or ions. The difficulties inherent to modeling this line are discussed with particular attention being paid to the likely influence of line-blanketing.

  5. An orthogonal wavelet division multiple-access processor architecture for LTE-advanced wireless/radio-over-fiber systems over heterogeneous networks

    NASA Astrophysics Data System (ADS)

    Mahapatra, Chinmaya; Leung, Victor CM; Stouraitis, Thanos

    2014-12-01

    The increase in internet traffic, number of users, and availability of mobile devices poses a challenge to wireless technologies. In long-term evolution (LTE) advanced system, heterogeneous networks (HetNet) using centralized coordinated multipoint (CoMP) transmitting radio over optical fibers (LTE A-ROF) have provided a feasible way of satisfying user demands. In this paper, an orthogonal wavelet division multiple-access (OWDMA) processor architecture is proposed, which is shown to be better suited to LTE advanced systems as compared to orthogonal frequency division multiple access (OFDMA) as in LTE systems 3GPP rel.8 (3GPP, http://www.3gpp.org/DynaReport/36300.htm). ROF systems are a viable alternative to satisfy large data demands; hence, the performance in ROF systems is also evaluated. To validate the architecture, the circuit is designed and synthesized on a Xilinx vertex-6 field-programmable gate array (FPGA). The synthesis results show that the circuit performs with a clock period as short as 7.036 ns (i.e., a maximum clock frequency of 142.13 MHz) for transform size of 512. A pipelined version of the architecture reduces the power consumption by approximately 89%. We compare our architecture with similar available architectures for resource utilization and timing and provide performance comparison with OFDMA systems for various quality metrics of communication systems. The OWDMA architecture is found to perform better than OFDMA for bit error rate (BER) performance versus signal-to-noise ratio (SNR) in wireless channel as well as ROF media. It also gives higher throughput and mitigates the bad effect of peak-to-average-power ratio (PAPR).

  6. Impact of non-LTE processes on middle atmospheric water vapor retrievals from simulated measurements of 6.8 μm Earth limb emission

    NASA Astrophysics Data System (ADS)

    Mertens, Christopher J.; Mlynczak, Martin G.; Lopez-Puertas, Manuel; Remsberg, Ellis E.

    2002-05-01

    We present an efficient and accurate algorithm for the retrieval of water vapor (H2O) volume mixing ratio (vmr) in the middle atmosphere from satellite measurements of 6.8 μm Earth limb emission, which rigorously includes non-local thermodynamic equilibrium (non-LTE) processes. A number of retrieval studies have been conducted with this algorithm leading to three major conclusions about the retrieval of H2O in the middle atmosphere: (1) satellite measurements of 6.3 μm limb emission must be made to high altitudes (85-90 km), where the few optically thick H2O absorption lines become optically thin, in order to prevent large errors in retrieved stratospheric and mesospheric H2O vmr; (2) the impact of non-LTE on nighttime H2O retrievals is greater than previously thought; (3) the enhancements in the daytime H2O channel radiances of the NIMBUS 7 LIMS experiment may be entirely due to non-LTE emission from the H2O 6.3 μm bands.

  7. Bidirectional and Multi-User Telerehabilitation System: Clinical Effect on Balance, Functional Activity, and Satisfaction in Patients with Chronic Stroke Living in Long-Term Care Facilities

    PubMed Central

    Lin, Kwan-Hwa; Chen, Chin-Hsing; Chen, You-Yin; Huang, Wen-Tzeng; Lai, Jin-Shin; Yu, Shang-Ming; Chang, Yuan-Jen

    2014-01-01

    Background The application of internet technology for telerehabilitation in patients with stroke has developed rapidly. Objective The current study aimed to evaluate the effect of a bidirectional and multi-user telerehabilitation system on balance and satisfaction in patients with chronic stroke living in long-term care facilities (LTCFs). Method This pilot study used a multi-site, blocked randomization design. Twenty-four participants from three LTCFs were recruited, and the participants were randomly assigned into the telerehabilitation (Tele) and conventional therapy (Conv) groups within each LTCF. Tele group received telerehabilitation but the Conv group received conventional therapy with two persons in each group for three sessions per week and for four weeks. The outcome measures included Berg Balance Scale (BBS), Barthel Index (BI), and the telerehabilitation satisfaction of the participants. Setting A telerehabilitation system included “therapist end” in a laboratory, and the “client end” in LTCFs. The conventional therapy was conducted in LTCFs. Results Training programs conducted for both the Tele and Conv groups showed significant effects within groups on the participant BBS as well as the total and self-care scores of BI. No significant difference between groups could be demonstrated. The satisfaction of participants between the Tele and the Conv groups also did not show significant difference. Conclusions This pilot study indicated that the multi-user telerehabilitation program is feasible for improving the balance and functional activity similar to conventional therapy in patients with chronic stroke living in LTCFs. PMID:25019632

  8. Iterative Multiuser Detection with Soft Decision-Directed Channel Estimation for MC-IDMA and Performance Comparison with Chip-Interleaved MC-CDMA

    NASA Astrophysics Data System (ADS)

    Suyama, Satoshi; Suzuki, Hiroshi; Fukawa, Kazuhiko; Zhang, Li

    This paper applies iterative multiuser detection employing a new channel estimation scheme to multicarrier interleave-division multiple access (MC-IDMA), called OFDM-IDMA, which is expected to offer improved spectral efficiency in mobile communications. The MC-IDMA transmitter uses both a low-rate channel code and an individual chip interleaver for each user. The MC-IDMA receiver, which this paper focuses upon, repeats the iterative multiuser detection and soft decision-directed channel estimation (SDCE) by exploiting log-likelihood ratios (LLRs) of the coded bits which the maximum a posteriori (MAP)-based channel decoders for all users provide. SDCE estimates channel impulse responses of all users by the least-mean-square (LMS) algorithm, which aims to minimize the mean squared error between the received signal and its replica. This paper investigates the performance of MC-IDMA employing SDCE and compares it with those of three MC-CDMA techniques. Computer simulations demonstrate that MC-IDMA employing SDCE outperforms time-spread MC-CDMA and frequency-spread MC-CDMA, and that it can achieve almost the same bit error rate performance as chip-interleaved MC-CDMA while requiring lower complexity.

  9. Open M-shell Fe and Ni LTE opacity calculations with the code HULLAC-v9

    NASA Astrophysics Data System (ADS)

    Gilles, D.; Busquet, M.; Klapisch, M.; Gilleron, F.; Pain, J.-C.

    2015-09-01

    It has been shown that a careful evaluation of the Δn = 0 M-shell in Fe and Ni is necessary to obtain consistent stellar model predictions. At astrophysical conditions of Te = 15.3 eV, ne = 1013 1022cm-3, the Δn = 0 M-shell and absorption transitions among M to N and M to O shells arising from the ions Fe III through Fe XV, have been computed in the using detailed level accounting (DLA) with configuration interaction (CI), assuming LTE. The importance of extensive CI computations is shown by systematically increasing the size of the CI basis until convergence. Iron opacity results, including M-shell and M to upper shells transitions up to Δn = 2, are presented and the influence of the number of atomic levels is discussed. These very large computations -e.g. ˜7.3 × 105 levels or ˜5700 relativistic configurations in Fe VII- were performed using the flexibility and the efficiency of an updated version of the HULLAC-v9.5 code. Results for Ni are also reported. HULLAC-v9.5 results are compared with those of other codes and databases, STA, SCO-RCG and OPCD3.3.

  10. The Non-Lte Stagnation Physics Of A Z Pinch: Spectroscopy Coupled With Rad-Hydro Simulations

    NASA Astrophysics Data System (ADS)

    Mehlhorn, T.; Giuliani, J.; Thornhill, W.; Dasgupta, A.; Maron, Y.; Kroupp, E.; Rosenzweig, G.; Coverdale, C.; Apruzese, J.; Deeney, C.

    2015-11-01

    We present modeling of the non-LTE ionization kinetics in radiation-MHD simulations of Z pinches, focusing on the origin of the large effective ion temperatures and the energy balance during the stagnation phase. Effective ion temperatures (Tieff), based on the widths of emission lines, have long been reported to exceed the electron temperature by more than 10X. Ne gas puff experiments at the Weizmann Institute also display this effect, and provide extensive time and space resolved measurements of the plasma during stagnation. MACH2-TCRE has been used to model this Ne. Tieff has been computed analogously to the experimental technique. The 2D model results are significantly larger than the ion thermal temperatures early in the K-shell pulse, in agreement with the data. This implies that the broad line widths reflect strong radially velocity gradients near the axis. Spectroscopic data from Al/Ti arrays on Z at SNL and gas puffs at the Weizmann Institute indicate that the stagnating pinch is defined by an accreting shock with the pressure behind the shock balanced by the ram pressure of the imploding material. Polarization spectroscopy indicates that the magnetic field does not penetrate deeply into the stagnating plasma. Supported by DOE/NNSA.

  11. Non-LTE, line-blanketed model atmospheres for late O- and early B-type stars

    NASA Technical Reports Server (NTRS)

    Grigsby, James A.; Morrison, Nancy D.; Anderson, Lawrence S.

    1992-01-01

    The use of non-LTE line-blanketed model atmospheres to analyze the spectra of hot stars is reported. The stars analyzed are members of clusters and associations, have spectral types in the range O9-B2 and luminosity classes in the range III-IV, have slow to moderate rotation, and are photometrically constant. Sampled line opacities of iron-group elements were incorporated in the radiative transfer solution; solar abundances were assumed. Good to excellent agreement is obtained between the computed profiles and essentially all the line profiles used to fix the model, and reliable stellar parameters are derived. The synthetic M II 5581 equivalent widths agree well with the observed ones at the low end of the temperature range studied, but, above 25,000 K, the synthetic line is generally stronger than the observed line. The behavior of the observed equivalent widths of N II, N III, C II and C III lines as a function of Teff is studied. Most of the lines show much scatter, with no consistent trend that could indicate abundance differences from star to star.

  12. Reducing the power consumption in LTE-Advanced wireless access networks by a capacity based deployment tool

    NASA Astrophysics Data System (ADS)

    Deruyck, Margot; Joseph, Wout; Tanghe, Emmeric; Martens, Luc

    2014-09-01

    As both the bit rate required by applications on mobile devices and the number of those mobile devices are steadily growing, wireless access networks need to be expanded. As wireless networks also consume a lot of energy, it is important to develop energy-efficient wireless access networks in the near future. In this study, a capacity-based deployment tool for the design of energy-efficient wireless access networks is proposed. Capacity-based means that the network responds to the instantaneous bit rate requirements of the users active in the selected area. To the best of our knowledge, such a deployment tool for energy-efficient wireless access networks has never been presented before. This deployment tool is applied to a realistic case in Ghent, Belgium, to investigate three main functionalities incorporated in LTE-Advanced: carrier aggregation, heterogeneous deployments, and Multiple-Input Multiple-Output (MIMO). The results show that it is recommended to introduce femtocell base stations, supporting both MIMO and carrier aggregation, into the network (heterogeneous deployment) to reduce the network's power consumption. For the selected area and the assumptions made, this results in a power consumption reduction up to 70%. Introducing femtocell base stations without MIMO and carrier aggregation can already result in a significant power consumption reduction of 38%.

  13. Kinetic Requirements for the Measurement of Mesospheric Water Vapor at 6.8 (microns) under Non-LTE Conditions

    NASA Technical Reports Server (NTRS)

    Zhou, Daniel K.; Mlynczak, Martin G.; Lopez-Puertas, Manuel; Russell, James M., III

    1999-01-01

    We present accuracy requirements for specific kinetic parameters used to calculate the populations and vibrational temperatures of the H2O(010) and H2O(020) states in the terrestrial mesosphere. The requirements are based on rigorous simulations of the retrieval of mesospheric water vapor profiles from measurements of water vapor infrared emission made by limb scanning instruments on orbiting satellites. Major improvements in the rate constants that describe vibration-to- vibration exchange between the H2O(010) and 02(1) states are required in addition to improved specification of the rate of quenching Of O2(1) by atomic oxygen (0). It is also necessary to more accurately determine the yield of vibrationally excited O2(l) resulting from ozone photolysis. A contemporary measurement of the rate of quenching of H2O(010) by N2 and O2 is also desirable. These rates are either highly uncertain or have never before been measured at atmospheric temperatures. The suggested improvements are necessary for the interpretation of water vapor emission measurements at 6.8 microns to be made from a new spaceflight experiment in less than 2 years. The approach to retrieving water vapor under non-LTE conditions is also presented.

  14. Self-consistent Non-LTE Model of Infrared Molecular Emissions and Oxygen Dayglows in the Mesosphere and Lower Thermosphere

    NASA Technical Reports Server (NTRS)

    Feofilov, Artem G.; Yankovsky, Valentine A.; Pesnell, William D.; Kutepov, Alexander A.; Goldberg, Richard A.; Mauilova, Rada O.

    2007-01-01

    We present the new version of the ALI-ARMS (for Accelerated Lambda Iterations for Atmospheric Radiation and Molecular Spectra) model. The model allows simultaneous self-consistent calculating the non-LTE populations of the electronic-vibrational levels of the O3 and O2 photolysis products and vibrational level populations of CO2, N2,O2, O3, H2O, CO and other molecules with detailed accounting for the variety of the electronic-vibrational, vibrational-vibrational and vibrational-translational energy exchange processes. The model was used as the reference one for modeling the O2 dayglows and infrared molecular emissions for self-consistent diagnostics of the multi-channel space observations of MLT in the SABER experiment It also allows reevaluating the thermalization efficiency of the absorbed solar ultraviolet energy and infrared radiative cooling/heating of MLT by detailed accounting of the electronic-vibrational relaxation of excited photolysis products via the complex chain of collisional energy conversion processes down to the vibrational energy of optically active trace gas molecules.

  15. A non-LTE kinetic model for quick analysis of K-shell spectra from Z-pinch plasmas

    SciTech Connect

    Li, J. Huang, X. B. Cai, H. C. Yang, L. B. Xie, W. P. Duan, S. C.

    2014-12-15

    Analyzing and modeling K-shell spectra emitted by low-to moderate-atomic number plasma is a useful and effective way to retrieve temperature density of z-pinch plasmas. In this paper, a non-LTE population kinetic model for quick analysis of K-shell spectra was proposed. The model contains ionization stages from bare nucleus to neutral atoms and includes all the important atomic processes. In the present form of the model, the plasma is assumed to be both optically thin and homogeneous with constant temperature and density, and only steady-state situation is considered. According to the detailed calculations for aluminum plasmas, contours of ratios of certain K-shell lines in electron temperature and density plane as well as typical synthesized spectra were presented and discussed. The usefulness of the model is demonstrated by analyzing the spectrum from a neon gas-puff Z-pinch experiment performed on a 1 MA pulsed-power accelerator.

  16. Coverage Extension and Balancing the Transmitted Power of the Moving Relay Node at LTE-A Cellular Network

    PubMed Central

    Aldhaibani, Jaafar A.; Yahya, Abid; Ahmad, R. Badlishah

    2014-01-01

    The poor capacity at cell boundaries is not enough to meet the growing demand and stringent design which required high capacity and throughput irrespective of user's location in the cellular network. In this paper, we propose new schemes for an optimum fixed relay node (RN) placement in LTE-A cellular network to enhance throughput and coverage extension at cell edge region. The proposed approach mitigates interferences between all nodes and ensures optimum utilization with the optimization of transmitted power. Moreover, we proposed a new algorithm to balance the transmitted power of moving relay node (MR) over cell size and providing required SNR and throughput at the users inside vehicle along with reducing the transmitted power consumption by MR. The numerical analysis along with the simulation results indicates that an improvement in capacity for users is 40% increment at downlink transmission from cell capacity. Furthermore, the results revealed that there is saving nearly 75% from transmitted power in MR after using proposed balancing algorithm. ATDI simulator was used to verify the numerical results, which deals with real digital cartographic and standard formats for terrain. PMID:24672378

  17. Non-LTE radiative transfer with lambda-acceleration - Convergence properties using exact full and diagonal lambda-operators

    NASA Technical Reports Server (NTRS)

    Macfarlane, J. J.

    1992-01-01

    We investigate the convergence properties of Lambda-acceleration methods for non-LTE radiative transfer problems in planar and spherical geometry. Matrix elements of the 'exact' A-operator are used to accelerate convergence to a solution in which both the radiative transfer and atomic rate equations are simultaneously satisfied. Convergence properties of two-level and multilevel atomic systems are investigated for methods using: (1) the complete Lambda-operator, and (2) the diagonal of the Lambda-operator. We find that the convergence properties for the method utilizing the complete Lambda-operator are significantly better than those of the diagonal Lambda-operator method, often reducing the number of iterations needed for convergence by a factor of between two and seven. However, the overall computational time required for large scale calculations - that is, those with many atomic levels and spatial zones - is typically a factor of a few larger for the complete Lambda-operator method, suggesting that the approach should be best applied to problems in which convergence is especially difficult.

  18. CO concentration in the upper stratosphere and mesosphere of Titan: non-LTE analysis of VIMS dayside limb observations at 4.7 mu m.

    NASA Astrophysics Data System (ADS)

    Fabiano, F.; Lopez-Puertas, M.; Adriani, A.; Moriconi, M. L.; D'Aversa, E.; Funke, B.; Lopez-Valverde, M. A.; Ridolfi, M.; Dinelli, B. M.

    During the last 20 years, many works have focused on the atmospheric concentration of CO on Titan, giving contradictory results. In particular, no measurement of the CO abundance above 300 km has been done yet, due to the faint emission of CO above that altitude. On the other hand, such a study is particularly awaited as a confirmation of photochemical models that predict a uniform volume mixing ratio of CO in the whole Titan's atmosphere. Moreover, given that CO is the main reservoir of oxygen in Titan's atmosphere and its presence is linked to water, the matter is of astrobiological interest too. The analysis of VIMS (Visual & Infrared Mapping Spectrometer, onboard Cassini) daytime limb measurements of Titan at 4.7 mu m, corresponding to the vibrational bands of CO, allows such a study: CO molecules are significantly excited by solar radiation and the otherwise faint infrared signal of the upper atmosphere is large, allowing to probe this region too. On the other hand, the strong non-LTE behavior of CO infrared emission above 200 km, strongly coupled to N2 and CH4 vibrational levels, represents an extra complexity of the data analysis. In order to deal with CO non-LTE emission, we have developed a non-LTE excitation - de- excitation model for the first two CO vibrational levels of the two most abundant isotopo- logues. We consider the contribution of absorption of radiation in the fundamental, first hot and first overtone bands and evaluate the possible contribution of different collisional processes, mainly the coupling with the first excited state of N2 and with several levels of CH4. The solution of the non-LTE problem is obtained \\citep{Funke2012} through GRANADA , a non-LTE population algorithm based on Lambda iteration resolution strategy, eventually coupled to a Curtis-Matrix type approach. The result shows a significant over-population of the first vibrational level above 300km and of the second level in the whole atmosphere. The possibility of further

  19. The Effect of the Use of the 3-D Multi-User Virtual Environment "Second Life" on Student Motivation and Language Proficiency in Courses of Spanish as a Foreign Language

    ERIC Educational Resources Information Center

    Pares-Toral, Maria T.

    2013-01-01

    The ever increasing popularity of virtual worlds, also known as 3-D multi-user virtual environments (MUVEs) or simply virtual worlds provides language instructors with a new tool they can exploit in their courses. For now, "Second Life" is one of the most popular MUVEs used for teaching and learning, and although "Second Life"…

  20. Observations of non-LTE emission at 4 5 microns with the planetary Fourier spectrometer abord the Mars Express mission

    NASA Astrophysics Data System (ADS)

    Formisano, V.; Maturilli, A.; Giuranna, M.; D'Aversa, E.; Lopez-Valverde, M. A.

    2006-05-01

    We report on PFS-MEX (Planetary Fourier Spectrometer on board Mars Express) limb observations of the non-Local Thermodynamic Equilibrium emission by CO and CO 2 isotopic molecules. The CO emission is observed peaking at altitudes lower than the CO 2 emission peak. Two orbits have been considered, which explore latitudes from 75 to 15° N, located in local time at 11:30 and 06:40, and with L=138° and 168°, respectively. In general in the season considered (northern summer) the emission intensity increases going to lower latitudes. The peak emission height is also decreasing with decreasing latitude. The CO 2 isotopic molecules are emitting radiance out of proportion with respect to the normal isotopic abundance, which surely indicates a strong contribution from a large number of much weaker CO 2 bands, a result that will demand careful theoretical modeling. By comparison with Hitran data base we can identify, among the emitting bands, the second hot band for the 626 and 636 molecule, while for the 628 and 627 emission from the third hot bands are very possible. Other minor bands or lines are also observed in emission for the first time in Mars. In one of the two orbits considered, the orbit 1234 of MEX, we also observe at altitudes 80-85 km scattered radiation, with indication of CO 2 ice aerosols as scattering centers. At the same altitude the Pathfinder descending measurements show a temperature that allows CO 2 condensation. Pathfinder measurements were at 03:00 local time, while our observations are for orbit 1234 showing CO 2 ice signature at 11:30 local time. These non-LTE limb emissions, with their unprecedented spectral resolution in this portion of the near infrared and their sensitivity and geographical coverage, will represent in our opinion an excellent data set for testing current theoretical models of the martian upper atmosphere.

  1. Experiments on the Scaling of Ionization Balance vs. Electron and Radiation Temperature in Non-LTE Gold Plasmas

    SciTech Connect

    Heeter, R F; Hansen, S B; Beiersdorfer, P; Foord, M E; Fournier, K B; Froula, D H; Mackinnon, A J; May, M J; Schneider, M B; Young, B F

    2004-06-25

    Understanding and predicting the behavior of high-Z non-LTE plasmas is important for developing indirect-drive inertial confinement fusion. Extending earlier work from the Nova laser, we present results from experiments using the Omega laser to study the ionization balance of gold as a function of electron and radiation temperature. In these experiments, gold samples embedded in Be disks expand under direct laser heating to n{sub e} {approx} 10{sup 21} cm{sup -3}, with T{sub e} varying from 0.8 to 2.5 keV. An additional finite radiation field with effective temperature T{sub r} up to 150 eV is provided by placing the gold-Be disks inside truncated 1.2 mm diameter tungsten-coated cylindrical hohlraums with full laser entrance holes. Densities are measured by imaging of plasma expansion. Electron temperatures are diagnosed with either 2 {omega} or 4 {omega} Thomson scattering, and also K-shell spectroscopy of KCl tracers co-mixed with the gold. Hohlraum flux and effective radiation temperature are measured using an absolutely-calibrated multichannel filtered diode array. Spectroscopic measurements of the M-shell gold emission in the 2.9-4 keV spectral range provide ionization balance and charge state distribution information. The spectra show strong variation with T{sub e}, strong variation with the applied T{sub r} at T{sub e} below 1.6 keV, and relatively little variation with T{sub r} at higher T{sub e} (upwards of 2 keV). We summarize our most recent spectral analyses and discuss emerging and outstanding issues.

  2. Multiuser quantum communication networks

    SciTech Connect

    Wojcik, Antoni; Kurzynski, Pawel; Grudka, Andrzej; Luczak, Tomasz; Gdala, Tomasz; Bednarska, Malgorzata

    2007-02-15

    We study a quantum state transfer between spins interacting with an arbitrary network of spins coupled by uniform XX interactions. It is shown that in such a system under fairly general conditions, we can expect a nearly perfect transfer of states. Then we analyze a generalization of this model to the case of many network users, where the sender can choose which party he wants to communicate with by appropriately tuning his local magnetic field. We also remark that a similar idea can be used to create an entanglement between several spins coupled to the network.

  3. Variability of OH rotational temperatures on time scales from hours to 15 years by kinetic temperature variations, emission layer changes, and non-LTE effects

    NASA Astrophysics Data System (ADS)

    Noll, Stefan

    2016-07-01

    Rotational temperatures derived from hydroxyl (OH) line emission are frequently used to study atmospheric temperatures at altitudes of about 87 km. While the measurement only requires intensities of a few bright lines of an OH band, the interpretation can be complicated. Ground-based temperatures are averages for the entire, typically 8 km wide emission layer. Variations in the rotational temperature are then caused by changes of the kinetic temperature and the OH emission profile. The latter can also be accompanied by differences in the layer-averaged efficiency of the thermalisation of the OH rotational level populations. Since this especially depends on the frequency of collisions with O_2, which is low at high altitudes, the non-local thermodynamic equilibrium (non-LTE) contribution to the measured temperatures can be significant and variable. In order to understand the impact of the different sources of OH rotational temperature variations from time scales of hours to a solar cycle, we have studied spectra from the astronomical echelle spectrographs X-shooter and UVES located at Cerro Paranal in Chile. While the X-shooter data spanning 3.5 years allowed us to measure temperatures for 25 OH and two O_2 bands, the UVES spectra cover no more than 10 OH bands simultaneously but a period of about 15 years. These data have been complemented by kinetic temperature and OH and O_2 emission profiles from the multi-channel radiometer SABER on the TIMED satellite. Taking the O_2 and SABER kinetic temperatures as reference and considering the different band-dependent emission profiles, we could evaluate the contribution of non-LTE effects to the measured OH rotational temperatures depending on line set, band, and time. Non-LTE contributions are significant for most bands and can exceed 10 K. The amplitudes of their average nocturnal and seasonal variation are of the order of 1 to 2 K.

  4. Short characteristic solution of the non-LTE line transfer problem by operator perturbation. II - The two-dimensional planar slab

    NASA Astrophysics Data System (ADS)

    Kunasz, P. B.; Olson, Gordon L.

    1988-01-01

    The performance of the method of Kunasz and Auer (1988) in the treatment of the non-LTE transfer problem is investigated for a sample of physical models, and comparisons with the direct implicit solutions of Mihalis et al. (1978) are presented. Although the effect of two-dimensionality on performance is found to be minimal, the advantages in accuracy of quadratic over linear interpolation on spatial resolution are found to be significant. The practicality of using approximate operators with nearest-neighbor coupling is compared for the cases of one-dimensional and two-dimensional slabs.

  5. Concept design theory and model for multi-use space facilities: Analysis of key system design parameters through variance of mission requirements

    NASA Astrophysics Data System (ADS)

    Reynerson, Charles Martin

    This research has been performed to create concept design and economic feasibility data for space business parks. A space business park is a commercially run multi-use space station facility designed for use by a wide variety of customers. Both space hardware and crew are considered as revenue producing payloads. Examples of commercial markets may include biological and materials research, processing, and production, space tourism habitats, and satellite maintenance and resupply depots. This research develops a design methodology and an analytical tool to create feasible preliminary design information for space business parks. The design tool is validated against a number of real facility designs. Appropriate model variables are adjusted to ensure that statistical approximations are valid for subsequent analyses. The tool is used to analyze the effect of various payload requirements on the size, weight and power of the facility. The approach for the analytical tool was to input potential payloads as simple requirements, such as volume, weight, power, crew size, and endurance. In creating the theory, basic principles are used and combined with parametric estimation of data when necessary. Key system parameters are identified for overall system design. Typical ranges for these key parameters are identified based on real human spaceflight systems. To connect the economics to design, a life-cycle cost model is created based upon facility mass. This rough cost model estimates potential return on investments, initial investment requirements and number of years to return on the initial investment. Example cases are analyzed for both performance and cost driven requirements for space hotels, microgravity processing facilities, and multi-use facilities. In combining both engineering and economic models, a design-to-cost methodology is created for more accurately estimating the commercial viability for multiple space business park markets.

  6. Dynamics of quiescent prominence fine structures analyzed by 2D non-LTE modelling of the Hα line

    NASA Astrophysics Data System (ADS)

    Gunár, S.; Mein, P.; Schmieder, B.; Heinzel, P.; Mein, N.

    2012-07-01

    Aims: We analyze the dynamics of the prominence fine structures of a quiescent prominence observed on April 26, 2007 during a coordinated campaign of several spaceborne and ground-based instruments. We use Lyman spectra observed by SOHO/SUMER and the Hα line spectra obtained by MSDP spectrograph working at the Meudon Solar Tower. Methods: We employ the 2D multi-thread prominence fine-structure modelling that includes randomly distributed line-of-sight (LOS) velocities of individual threads to derive models producing synthetic Lyman lines in good agreement with the SOHO/SUMER observations. We then use these models to produce synthetic Hα line spectra that we compare with the observed spectra using three statistical parameters: the line integrated intensity, the line full-width at half-maximum (FWHM), and the Doppler velocity derived from shifts of the line profiles. Results: We demonstrate that the 2D multi-thread models that produce synthetic Lyman spectra in agreement with observations also generate synthetic Hα spectra in good agreement with the observed ones. The statistical analysis of the FWHM and Doppler velocities of the synthetic Hα line profiles show that the overall LOS velocities in the April 26, 2007 prominence at the time of the observations were below 15 km s-1 and in the prominence core were close to 10 km s-1. In combination with the analysis of the Lyman spectra, we determine several physical parameters of the observed prominence fine-structures that show that the April 26, 2007 prominence had a relatively low-mass weakly magnetized structure. We are also able to impose some constraints on the prominence core temperature, which may be relatively low, with values below 6000 K. Conclusions: The combination of 2D non-LTE prominence fine-structure modelling with the statistical analysis of the observed and synthetic Lyman and Hα spectra allows us to analyze the influence of the model input parameters and the velocity fields on the synthetic H

  7. Performance Evaluation in Heterogeneous Networks Employing Time-Domain Inter-Cell Interference Coordination and Cell Range Expansion for LTE-Advanced Downlink

    NASA Astrophysics Data System (ADS)

    Shirakabe, Masashige; Morimoto, Akihito; Miki, Nobuhiko

    In Long-Term Evolution (LTE)-Advanced, heterogeneous networks where femtocells and picocells are overlaid onto macrocells are extensively discussed in addition to traditional well-planned macrocell deployment to improve further the system throughput. In heterogeneous network deployment, combined usage of inter-cell interference coordination (ICIC) and cell range expansion (CRE) is very effective in improving the system and cell-edge throughput. In this combined usage, the fraction of the sets of user equipment (UEs) connected to the picocells, which are controlled through CRE, and that connected to macrocells affect the gain from the ICIC. Therefore, this paper evaluates the throughput performance of different offset values for CRE and different amounts of protected resources for ICIC in picocell deployments in LTE-Advanced downlink. Simulation results (2-10 picocells and 30 UEs are located within 1 macrocell) assuming a full buffer traffic model show that when the CRE offset value is set between 8 to 20dB, almost the same user throughput performance is obtained by allocating the appropriate resources to protect UEs that connect to the picocells. Furthermore, the appropriate resource ratio is derived based on the fraction of UEs connected to the picocells through CRE, the fraction of UEs connected to the macrocell, and the number of picocells under the simulation conditions.

  8. Predictions of non-LTE spectra from large scale 3D magneto-hydrodynamic modelling of wire array Z-pinches

    NASA Astrophysics Data System (ADS)

    Niasse, Nicolas; Chittenden, Jeremy

    2012-10-01

    The last few years have seen considerable advances in the application of high performance computing techniques to 3D simulations of wire array Z-pinches. Whilst the intense soft X-ray radiation output is the principle application of wire arrays, the ability to encompass spectrally detailed models of this emission within such 3D calculations was thought to be computationally prohibitive. We have developed a non-LTE atomic and radiation physics model with detailed configuration accounting and n-l splitting which is sufficiently streamlined to run in-line with large scale 3D simulations. In order to handle the volume of data generated by the spectral treatment of the billions of numerical cells, a novel data structure derived from a self-balancing binary search tree was developed, enabling the use of non-LTE DCA calculations within large scale 3D simulations for the first time. A brief description of the model is provided and the application of the simulations to understanding the X-ray generation processes within wire array Z-pinches on the Z generator at Sandia National Laboratory is reported. The contribution of the ion temperature and the motion of the unstable plasma at stagnation to the Doppler widths of the lines is described in detail.

  9. New routine for calculating non-LTE infrared cooling/heating rates in the Earth mesosphere and lower thermosphere for applications in GCMs

    NASA Astrophysics Data System (ADS)

    Kutepov, A.; Feofilov, A.; Medvedev, A. S.

    2012-12-01

    We developed a new fast and accurate routine for calculating the non-LTE radiative cooling/heating (C/H) rates in CO2 bands in the Earth mesosphere/lower thermosphere. This routine: a) utilizes exact accelerated lambda iteration (ALI) solution of the multilevel vibrational problem in CO2; b) applies the opacity distribution function (ODF) technique for fast and accurate treatment of the radiative transfer in the CO2 bands; c) accounts for the heating due to absorption of the near infrared solar radiation; c) allows varying input collisional rate coefficients and the O3P density; d) accounts for additional C/H caused by temperature and O3P/CO2 density fluctuations associated with small-scale gravity waves, which are not resolved in current GCMs, e) calculates C/H with a prescribed accuracy. New routine is about 10000 times faster than the line by line (LBL) approach when reproducing C/H above 65 km with accuracy of ± 0.3 K/day. We compare it with the existing non-LTE C/H parametrizations, and provide recommendations for its implementation in GCMs.

  10. NLTE and LTE Lick Indices for Red Giants from [Fe/H] 0.0 to -6.0 at SDSS and IDS Spectral Resolution

    NASA Astrophysics Data System (ADS)

    Short, C. Ian; Young, Mitchell E.; Layden, Nicholas

    2015-09-01

    We investigate the dependence of the complete system of 22 Lick indices on overall metallicity scaled from solar abundances, [{{M}}/{{H}}], from the solar value, 0.0, down to the extremely metal-poor (XMP) value of -6.0, for late-type giant stars (MK luminosity class III, {log}g=2.0) of MK spectral class late-K to late-F (3750\\lt {T}{eff}\\lt 6500 K) of the type that are detected as “fossils” of early galaxy formation in the Galactic halo and in extra-galactic structures. Our investigation is based on synthetic index values, I, derived from atmospheric models and synthetic spectra computed with PHOENIX in Local Thermodynamic Equilibrium (LTE) and Non-LTE (NLTE), where the synthetic spectra have been convolved to the spectral resolution, R, of both IDS and SDSS (and LAMOST) spectroscopy. We identify nine indices, that we designate “Lick-XMP,” that remain both detectable and significantly [{{M}}/{{H}}]-dependent down to [{{M}}/{{H}}] values of at least ˜ -5.0, and down to [{{M}}/{{H}}] ˜ -6.0 in five cases, while also remaining well-behaved (single-valued as a function of [{{M}}/{{H}}] and positive in linear units). For these nine indices, we study the dependence of I on NLTE effects, and on spectral resolution. For our LTE I values for spectra of SDSS resolution, we present the fitted polynomial coefficients, {C}{{n}}, from multi-variate linear regression for I with terms up to third order in the independent variable pairs ({T}{eff}, [{{M}}/{{H}}] ) and (V-K, [{{M}}/{{H}}]), and compare them to the fitted {C}{{n}} values of Worthey et al. at IDS spectral resolution. For this fitted I data-set we present tables of LTE partial derivatives, \\frac{\\partial I}{\\partial {T}{eff}}{| }[{{M}/{{H}}]}, \\frac{\\displaystyle \\partial I}{\\partial [{{M}}/{{H}}]}{| }{T{eff}}, \\frac{\\displaystyle \\partial I}{\\partial (V-K)}{| }[{{M}/{{H}}]}, and \\frac{\\partial I}{\\partial [{{M}}/{{H}}]}{| }(V-K), that can be used to infer the relation between a given

  11. Systematic Non-LTE Study of the -2.6 < [Fe/H] < 0.2 F and G dwarfs in the Solar Neighborhood. I. Stellar Atmosphere Parameters

    NASA Astrophysics Data System (ADS)

    Sitnova, T.; Zhao, G.; Mashonkina, L.; Chen, Y.; Liu, F.; Pakhomov, Yu.; Tan, K.; Bolte, M.; Alexeeva, S.; Grupp, F.; Shi, J.-R.; Zhang, H.-W.

    2015-08-01

    We present atmospheric parameters for 51 nearby F and G dwarf and subgiant stars uniformly distributed over the -2.60< [{Fe}/{{H}}]< +0.20 metallicity range that is suitable for the Galactic chemical evolution research. Lines of iron in the two ionization stages, Fe I and Fe II, were used to derive a homogeneous set of effective temperatures, surface gravities, iron abundances, and microturbulence velocities. Our spectroscopic analyses took advantage of employing high-resolution (R ≥ 60,000) Shane/Hamilton and Canada-France-Hawaii Telescope/ESPaDOnS observed spectra and non-LTE (NLTE) line formation for Fe I and Fe II in the classical one-dimensional model atmospheres. The spectroscopic method was tested in advance with the 20 benchmark stars, for which there are multiple measurements of the infrared flux method effective temperature and their Hipparcos parallax error is less than 10%. We found NLTE abundances from lines of Fe I and Fe II to be consistent within 0.06 dex for every benchmark star, when applying a scaling factor of {S}{{H}} = 0.5 to the Drawinian rates of inelastic Fe+H collisions. The obtained atmospheric parameters were checked for each program star by comparing its position in the log g-{T}{eff} plane with the theoretical evolutionary track of given metallicity and α-enhancement in the Yi et al. grid. Our final effective temperatures lie exactly in between the {T}{IRFM} scales of Alonso et al. and Casagrande et al., with a mean difference of +46 and -51 K, respectively. NLTE leads to higher surface gravity compared with that for LTE. The shift in log g is smaller than 0.1 dex for stars with [Fe/H] ≥slant -0.75, {T}{eff} ≤ 5750 K, or log g ≥ 4.20. NLTE analysis is crucial for the very metal-poor turnoff and subgiant stars, for which the shift in log g between NLTE and LTE can be up to 0.5 dex. The obtained accurate atmospheric parameters will be used in the forthcoming papers to determine NLTE abundances of important astrophysical elements

  12. Do students with higher self-efficacy exhibit greater and more diverse scientific inquiry skills: An exploratory investigation in "River City", a multi-user virtual environment

    NASA Astrophysics Data System (ADS)

    Ketelhut, Diane Jass

    In this thesis, I conduct an exploratory study to investigate the relationship between students' self-efficacy on entry into authentic scientific activity and the scientific inquiry behaviors they employ while engaged in that process, over time. Scientific inquiry has been a major standard in most science education policy doctrines for the past two decades and is exemplified by activities such as making observations, formulating hypotheses, gathering and analyzing data, and forming conclusions from that data. The self-efficacy literature, however, indicates that self-efficacy levels affect perseverance and engagement. This study investigated the relationship between these two constructs. The study is conducted in a novel setting, using an innovative science curriculum delivered through an interactive computer technology that recorded each student's conversations, movements, and activities while behaving as a practicing scientist in a "virtual world" called River City. River City is a Multi-User Virtual Environment designed to engage students in a collaborative scientific inquiry-based learning experience. As a result, I was able to follow students' moment-by-moment choices of behavior while they were behaving as scientists. I collected data on students' total scientific inquiry behaviors over three visits to River City, as well as the number of sources from which they gathered their scientific data. I analyzed my longitudinal data on the 96 seventh-graders using individual growth modeling. I found that self-efficacy played a role in the number of data-gathering behaviors students engaged in initially, with high self-efficacy students engaging in more data gathering than students with low self-efficacy. However, the impact of student self-efficacy on rate of change in data gathering behavior differed by gender; by the end of the study, student self-efficacy did not impact data gathering. In addition, students' level of self-efficacy did not affect how many different

  13. An open-source, massively parallel code for non-LTE synthesis and inversion of spectral lines and Zeeman-induced Stokes profiles

    NASA Astrophysics Data System (ADS)

    Socas-Navarro, H.; de la Cruz Rodríguez, J.; Asensio Ramos, A.; Trujillo Bueno, J.; Ruiz Cobo, B.

    2015-05-01

    With the advent of a new generation of solar telescopes and instrumentation, interpreting chromospheric observations (in particular, spectropolarimetry) requires new, suitable diagnostic tools. This paper describes a new code, NICOLE, that has been designed for Stokes non-LTE radiative transfer, for synthesis and inversion of spectral lines and Zeeman-induced polarization profiles, spanning a wide range of atmospheric heights from the photosphere to the chromosphere. The code features a number of unique features and capabilities and has been built from scratch with a powerful parallelization scheme that makes it suitable for application on massive datasets using large supercomputers. The source code is written entirely in Fortran 90/2003 and complies strictly with the ANSI standards to ensure maximum compatibility and portability. It is being publicly released, with the idea of facilitating future branching by other groups to augment its capabilities. The source code is currently hosted at the following repository: http://https://github.com/hsocasnavarro/NICOLE

  14. Aspirin-intolerant asthma (AIA) assessment using the urinary biomarkers, leukotriene E4 (LTE4) and prostaglandin D2 (PGD2) metabolites.

    PubMed

    Higashi, Noritaka; Taniguchi, Masami; Mita, Haruhisa; Yamaguchi, Hiromichi; Ono, Emiko; Akiyama, Kazuo

    2012-09-01

    The clinical syndrome of aspirin-intolerant asthma (AIA) is characterized by aspirin/nonsteroidal anti-inflammatory drug intolerance, bronchial asthma, and chronic rhinosinusitis with nasal polyposis. AIA reactions are evidently triggered by pharmacological effect of cyclooxygenase-1 inhibitors. Urine sampling is a non-invasive research tool for time-course measurements in clinical investigations. The urinary stable metabolite concentration of arachidonic acid products provides a time-integrated estimate of the production of the parent compounds in vivo. AIA patients exhibits significantly higher urinary concentrations of leukotriene E(4) (LTE(4)) and 1,15-dioxo-9α-hydroxy-2,3,4,5-tetranorprostan-1,20-dioic acid (tetranor-PGDM), a newly identified metabolite of PGD(2), at baseline. This finding suggests the possibility that increased mast cell activation is involved in the pathophysiology of AIA even in a clinically stable condition. In addition, lower urinary concentrations of primary prostaglandin E(2) and 15-epimer of lipoxin A(4) at baseline in the AIA patients suggest that the impaired anti-inflammatory elements may also contribute to the severe clinical outcome of AIA. During the AIA reaction, the urinary concentrations of LTE(4) and PGD(2) metabolites, including tetranor-PGDM significantly and correlatively increase. It is considered that mast cell activation probably is a pathophysiologic hallmark of AIA. However, despite the fact that cyclooxygenease-1 is the dominant in vivo PGD(2) biosynthetic pathway, the precise mechanism underlying the PGD(2) overproduction resulting from the pharmacological effect of cyclooxygenease-1 inhibitors in AIA remains unknown. A comprehensive analysis of the urinary concentration of inflammatory mediators may afford a new research target in elucidating the pathophysiology of AIA. PMID:22627848

  15. A non-LTE spectral analysis of the 3He and 4He isotopes in the HgMn star κ Cancri

    NASA Astrophysics Data System (ADS)

    Maza, Natalia L.; Nieva, María-Fernanda; Przybilla, Norbert

    2014-12-01

    Aims: We present a pilot study on non-local thermodynamic equilibrium (NLTE) line-formation computations for the isotopes 3He and 4He in the mercury-manganese star κ Cancri. The impact of NLTE effects on the determination of isotopic abundances and the vertical stratification of helium in the atmosphere is investigated. Methods: Modern NLTE line-formation computations were employed to analyse a high-resolution and high signal-to-noise ratio ESO-VLT/UVES spectrum of κ Cnc. The atmospheric parameters were determined from fitting the hydrogen Balmer lines and the spectral energy distribution. Multiple He i lines were investigated, including He i λ4921 Å and λ6678 Å, which show the widest isotopic splits. Results: Half of the observed He i lines in the spectrum of κ Cnc show significant NLTE strengthening, the effects are strongest in the red lines He iλ5875 Å and He iλ6678 Å. NLTE abundances from individual He i lines are up to a factor of ~3 lower than LTE values. Helium is found to be stratified in the atmosphere of κ Cnc. While the LTE analysis indicates a step-like profile of the helium abundance, a gradual decrease with height is indicated by the NLTE analysis. A 3He/4He ratio of ~0.25-0.30 is found. With the available data it cannot be decided whether the two isotopes follow the same stratification profile, or not. Conclusions: This work implies that NLTE effects may be ubiquitous in the atmospheres of HgMn stars and may have a significant impact on abundance determinations and the interpretation of the vertical abundance stratification of elements. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 076.B-0055(A).Figures 3 and 4 are available in electronic form at http://www.aanda.org

  16. Using a multi-user desktop-based virtual reality system to recreate the São Miguel das Missões ruins.

    PubMed

    dos Santos, Selan R; Fraga, Letícia S

    2002-10-01

    This paper presents a project initiated back in 1999, in which Virtual Reality is applied in order to create a virtual community over the Internet. The desktop-based multi-user virtual reality system recreates a three-dimensional environment based on photogrammetric maps from the São Miguel das Missões church ruins. The ruins correspond to one of the Jesuit Mission (settlement) which was active in the south of Brazil in the 17th and 18th centuries. It has a great importance to the local region in terms of cultural, historic, and tourist aspects. It has also been inscribed in the UNESCO's world heritage list since 1983. This electronic mock-up allows several interactive operations such as community chats, electronic message exchanging, message boards, walking-through, discussion groups, and embedding of other media such as movies, sound, and html pages. The only requirement necessary to access the community is a web browser powered with any Virtual Reality Modeling Language (VRML) plug-in freely available over the Internet. It is expected that such a solution improves the conservation and dissemination of the Brazilian historic patrimony, congregating history, art, and tourist information in one place on the Internet. PMID:12448784

  17. The Multi-User Droplet Combustion Apparatus: the Development and Integration Concept for Droplet Combustion Payloads in the Fluids and Combustion Facility Combustion Integrated Rack

    NASA Astrophysics Data System (ADS)

    Myhre, C. A.

    2002-01-01

    The Multi-user Droplet Combustion Apparatus (MDCA) is a multi-user facility designed to accommodate four different droplet combustion science experiments. The MDCA will conduct experiments using the Combustion Integrated Rack (CIR) of the NASA Glenn Research Center's Fluids and Combustion Facility (FCF). The payload is planned for the International Space Station. The MDCA, in conjunction with the CIR, will allow for cost effective extended access to the microgravity environment, not possible on previous space flights. It is currently in the Engineering Model build phase with a planned flight launch with CIR in 2004. This paper provides an overview of the capabilities and development status of the MDCA. The MDCA contains the hardware and software required to conduct unique droplet combustion experiments in space. It consists of a Chamber Insert Assembly, an Avionics Package, and a multiple array of diagnostics. Its modular approach permits on-orbit changes for accommodating different fuels, fuel flow rates, soot sampling mechanisms, and varying droplet support and translation mechanisms to accommodate multiple investigations. Unique diagnostic measurement capabilities for each investigation are also provided. Additional hardware provided by the CIR facility includes the structural support, a combustion chamber, utilities for the avionics and diagnostic packages, and the fuel mixing capability for PI specific combustion chamber environments. Common diagnostics provided by the CIR will also be utilized by the MDCA. Single combustible fuel droplets of varying sizes, freely deployed or supported by a tether are planned for study using the MDCA. Such research supports how liquid-fuel-droplets ignite, spread, and extinguish under quiescent microgravity conditions. This understanding will help us develop more efficient energy production and propulsion systems on Earth and in space, deal better with combustion generated pollution, and address fire hazards associated with

  18. Non-LTE analysis of extremely helium-rich stars. The hot sdO stars LSE 153, 259 and 263

    NASA Technical Reports Server (NTRS)

    Husfeld, D.; Butler, K.; Heber, U.; Drilling, J. S.

    1989-01-01

    Results of a non-LTE fine analysis based mainly on high-resolution CASPEC spectra for three extremely helium-rich sdO stars are discussed in order to explain hydrogen deficiency in single stars. High temperature (Teff = 70,000 to 75,000 K) and a position in the log Teff - log g diagram were found close to the Eddington limit. Various abundance estimates are derived for hydrogen (upper limits only), carbon, nitrogen, and magnesium. Hydrogen is reduced to less than 10 percent by number in LSE 153 and LSE 263, and to less than 5 percent in LSE 259. The hydrogen deficiency is accompanied by nitrogen- and carbon-enrichment in LSE 153 and LSE 259 only. In LSE 263, carbon is depleted by about 1 dex. Stellar masses obtained by assuming that a core mass-luminosity relation holds for these stars, were found to be in the range 0.6-0.9 solar mass, yielding luminosities log L/L:solar = 3.7-4.5. Two of the program stars (LSE 153 and 259) appear to be possible successors of the R CrB and helium B stars, whereas the third star (LSE 263) displays a much lower carbon content in its photosphere making it an exceptional case among the known hydrogen deficient stars.

  19. Adenovirus-associated health risks for recreational activities in a multi-use coastal watershed based on site-specific quantitative microbial risk assessment.

    PubMed

    Kundu, Arti; McBride, Graham; Wuertz, Stefan

    2013-10-15

    We used site-specific quantitative microbial risk assessment (QMRA) to assess the probability of adenovirus illness for three groups of swimmers: adults with primary contact, children with primary contact, and secondary contact regardless of age. Human enteroviruses and adenoviruses were monitored by qPCR in a multi-use watershed and Adenovirus type 40/41 was detected in 11% of 73 samples, ranging from 147 to 4117 genomes per liter. Enterovirus was detected only once (32 genomes per liter). Seven of eight virus detections occurred when E. coli concentrations were below the single sample maximum water quality criterion for contact recreation, and five of eight virus detections occurred when fecal coliforms were below the corresponding criterion. We employed dose-harmonization to convert viral genome measurements to TCID50 values needed for dose-response curves. The three scenarios considered different amounts of water ingestion and Monte Carlo simulation was used to account for the variability associated with the doses. The mean illness risk in children based on adenovirus measurements obtained over 11 months was estimated to be 3.5%, which is below the 3.6% risk considered tolerable by the current United States EPA recreational criteria for gastrointestinal illnesses (GI). The mean risks of GI illness for adults and secondary contact were 1.9% and 1.0%, respectively. These risks changed appreciably when different distributions were fitted to the data as determined by Monte Carlo simulations. In general, risk was at a maximum for the log-logistic distribution and lowest for the hockey stick distribution in all three selected scenarios. Also, under default assumptions, the risk was lowered considerably when assuming that only a small proportion of Adenovirus 40/41 (3%) was as infectious as Adenovirus type 4, compared to the assumption that all genomes were Adenovirus 4. In conclusion, site-specific QMRA on water-borne adenoviruses in this watershed provided a similar

  20. The socio-cultural importance of Mauritia flexuosa palm swamps (aguajales) and implications for multi-use management in two Maijuna communities of the Peruvian Amazon

    PubMed Central

    2013-01-01

    only focus on the commercial harvest of aguaje but also other facets of their relationship with this habitat. Our study suggests that the research and development of multi-use forest management plans must not be restricted to commercial forest products and ecosystem services given that many communities rely on tropical forests for a wide range of non-market cultural, economic, and subsistence goods and services. PMID:23607601

  1. A NON-LTE ANALYSIS OF THE HOT SUBDWARF O STAR BD+28 Degree-Sign 4211. I. THE UV SPECTRUM

    SciTech Connect

    Latour, M.; Fontaine, G.; Brassard, P.; Chayer, P.

    2013-08-20

    We present a detailed analysis of the UV spectrum of the calibration star BD+28 Degree-Sign 4211 using high-quality spectra obtained with the Hubble Space Telescope and Far-Ultraviolet Spectroscopic Explorer satellites. To this aim, we compare quantitatively the observed data with model spectra obtained from state-of-the-art non-LTE metal line-blanketed model atmospheres and synthetic spectra calculated with TLUSTY and SYNSPEC. We thus determine in a self-consistent way the abundances of 11 elements with well-defined lines in the UV, namely those of C, N, O, F, Mg, Si, P, S, Ar, Fe, and Ni. The derived abundances range from about solar to 1/10 solar. We find that the overall quality of the derived spectral fits is very satisfying. Our spectral analysis can be used to constrain rather tightly the effective temperature of BD+28 Degree-Sign 4211 to a value of T{sub eff} = 82, 000 {+-} 5000 K. We also estimate conservatively that its surface gravity falls in the range log g = 6.2{sub -0.1}{sup +0.3}. Assuming that the Hipparcos measurement for BD+28 Degree-Sign 4211 is fully reliable and that our model atmospheres are reasonably realistic, we can reconcile our spectroscopic constraints with the available parallax measurement only if the mass of BD+28 Degree-Sign 4211 is significantly less than the canonical value of 0.5 M{sub Sun} for a representative post-extended horizontal branch star.

  2. A Coordinated X-Ray and Optical Campaign of the Nearest Massive Eclipsing Binary, δ Orionis Aa. IV. A Multiwavelength, Non-LTE Spectroscopic Analysis

    NASA Astrophysics Data System (ADS)

    Shenar, T.; Oskinova, L.; Hamann, W.-R.; Corcoran, M. F.; Moffat, A. F. J.; Pablo, H.; Richardson, N. D.; Waldron, W. L.; Huenemoerder, D. P.; Maíz Apellániz, J.; Nichols, J. S.; Todt, H.; Nazé, Y.; Hoffman, J. L.; Pollock, A. M. T.; Negueruela, I.

    2015-08-01

    Eclipsing systems of massive stars allow one to explore the properties of their components in great detail. We perform a multi-wavelength, non-LTE analysis of the three components of the massive multiple system δ Ori A, focusing on the fundamental stellar properties, stellar winds, and X-ray characteristics of the system. The primary’s distance-independent parameters turn out to be characteristic for its spectral type (O9.5 II), but usage of the Hipparcos parallax yields surprisingly low values for the mass, radius, and luminosity. Consistent values follow only if δ Ori lies at about twice the Hipparcos distance, in the vicinity of the σ-Orionis cluster. The primary and tertiary dominate the spectrum and leave the secondary only marginally detectable. We estimate the V-band magnitude difference between primary and secondary to be {{Δ }}V≈ 2\\buildrel{{m}}\\over{.} 8. The inferred parameters suggest that the secondary is an early B-type dwarf (≈B1 V), while the tertiary is an early B-type subgiant (≈B0 IV). We find evidence for rapid turbulent velocities (∼200 km s‑1) and wind inhomogeneities, partially optically thick, in the primary’s wind. The bulk of the X-ray emission likely emerges from the primary’s stellar wind ({log}{L}{{X}}/{L}{Bol}≈ -6.85), initiating close to the stellar surface at {R}0∼ 1.1 {R}*. Accounting for clumping, the mass-loss rate of the primary is found to be {log}\\dot{M}≈ -6.4 ({M}ȯ {{yr}}-1), which agrees with hydrodynamic predictions, and provides a consistent picture along the X-ray, UV, optical, and radio spectral domains.

  3. Simple Analytic Collisional Rates for non-LTE Vibrational Populations in Astrophysical Environments: the Cases of Circumstellar SiO Masers and Shocked H2

    NASA Astrophysics Data System (ADS)

    Bieniek, Ronald

    2008-05-01

    Rates for collisionally induced transitions between molecular vibrational levels are important in modeling a variety of non-LTE processes in astrophysical environments. Two examples are SiO masering in circumstellar envelopes in certain late-type stars [1] and the vibrational populations of molecular hydrogen in shocked interstellar medium [cf 2]. A simple exponential-potential model of molecular collisions leads to a two-parameter analytic expression for state-to-state and thermally averaged rates for collisionally induced vibrational-translational (VT) transitions in diatomic molecules [3,4]. The thermally averaged rates predicted by this formula have been shown to be in excellent numerical agreement with absolute experimental and quantum mechanical rates over large temperature ranges and initial vibrational excitation levels in a variety of species, e.g., OH, O2, N2 [3] and even for the rate of H2(v=1)+H2, which changes by five orders of magnitude in the temperature range 50-2000 K [4]. Analogous analytic rates will be reported for vibrational transitions in SiO due to collisions with H2 and compared to the numerical fit of quantum-mechanical rates calculated by Bieniek and Green [5]. [1] Palov, A.P., Gray, M.D., Field, D., & Balint-Kurti, G.G. 2006, ApJ, 639, 204. [2] Flower, D. 2007, Molecular Collisions in the Interstellar Medium (Cambridge: Cambridge Univ. Press) [3] Bieniek, R.J. & Lipson, S.J. 1996, Chem. Phys. Lett. 263, 276. [4] Bieniek, R.J. 2006, Proc. NASA LAW (Lab. Astrophys. Workshop) 2006, 299; http://www.physics.unlv.edu/labastro/nasalaw2006proceedings.pdf. [5] Bieniek, R.J., & Green, S. 1983, ApJ, 265, L29 and 1983, ApJ, 270, L101.

  4. Analyzing non-LTE Kr plasmas produced in high energy density experiments: from the Z machine to the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Dasgupta, Arati

    2015-11-01

    Designing high fluence photon sources above 10 keV are a challenge for High Energy Density plasmas. This has motivated radiation source development investigations of Kr with K-shell energies around 13 keV. Recent pulsed power driven gas-puff experiments on the refurbished Z machine at Sandia have produced intense X-rays in the multi-keV photon energy range. K-shell radiative yields and efficiencies are very high for Ar, but rapidly decrease for higher atomic number (ZA) elements such as Kr. It has been suggested that an optimum exists corresponding to a trade-off between the increase of photon energy for higher ZA elements and the corresponding fall off in radiative power. However the conversion efficiency on NIF, where the drive, energy deposition process, and target dynamics are different, does not fall off with higher ZA as rapidly as on Z. We have developed detailed atomic structure and collisional data for the full K-, L- and partial M-shell of Kr using the Flexible Atomic Code (FAC). Our non-LTE atomic model includes all collisional and recombination processes, including state-specific dielectronic recombination (DR), that significantly affect ionization balance and spectra of Kr plasmas at the temperatures and densities of concern. The model couples ionization physics, radiation production and transport, and magnetohydrodynamics. In this talk, I will give a detailed description of the model and discuss 1D Kr simulations employing a multifrequency radiation transport scheme. Synthetic K- and L-shell spectra will be compared with available experimental data. This talk will analyze experimental data indicative of the differences between Z and NIF experimental data and discuss how they affect the K-shell radiative output of Kr plasma. Work supported by DOE/NNSA.

  5. Multiuser development scenario for ICF

    SciTech Connect

    Hogan, W.J.

    1985-10-01

    An outline is given of some of the various possible applications of ICF technology. Developmental paths for each application are briefly described. The implications on design and operation of the ICF facilities if multipurpose use is allowed are examined. (MOW)

  6. Multi-user investigation organizer

    NASA Technical Reports Server (NTRS)

    Keller, Richard M. (Inventor); Panontin, Tina L. (Inventor); Carvalho, Robert E. (Inventor); Sturken, Ian (Inventor); Williams, James F. (Inventor); Wolfe, Shawn R. (Inventor); Gawdiak, Yuri O. (Inventor)

    2009-01-01

    A system that allows a team of geographically dispersed users to collaboratively analyze a mishap event. The system includes a reconfigurable ontology, including instances that are related to and characterize the mishap, a semantic network that receives, indexes and stores, for retrieval, viewing and editing, the instances and links between the instances, a network browser interface for retrieving and viewing screens that present the instances and links to other instances and that allow editing thereof, and a rule-based inference engine, including a collection of rules associated with establishment of links between the instances. A possible conclusion arising from analysis of the mishap event may be characterized as one or more of: not a credible conclusion; an unlikely conclusion; a credible conclusion; conclusion needs analysis; conclusion needs supporting data; conclusion proposed to be closed; and an un-reviewed conclusion.

  7. One-dimensional non-LTE time-dependent radiative transfer of an He-detonation model and the connection to faint and fast-decaying supernovae

    NASA Astrophysics Data System (ADS)

    Dessart, Luc; Hillier, D. John

    2015-02-01

    We present non-LTE (non-Local-Thermodynamic-Equilibrium) time-dependent radiative transfer simulations for ejecta produced by the detonation of a helium shell at the surface of a low-mass carbon/oxygen white dwarf (WD). This mechanism is one possible origin for supernovae (SNe) with faint and fast-decaying light curves, such as .Ia SNe and Ca-rich transients. Our initial ejecta conditions at 1 d are given by the 0.18 B explosion model COp45HEp2 of Waldman et al. The 0.2 M⊙ ejecta initially contains 0.11 M⊙ of He, 0.03 M⊙ of Ca, and 0.03 M⊙ of Ti. We obtain an ˜ 5 d rise to a bolometric maximum of 3.59 × 1041 erg s-1, primarily powered by 48V decay. Multi-band light curves show distinct morphologies, with a rise to maximum magnitude (-14.3 to -16.7 mag) that varies between 3 to 9 d from the U to the K bands. Near-IR light curves show no secondary maximum. Because of the presence of both He I and Si II lines at early times we obtain a hybrid Type Ia/Ib classification. During the photospheric phase line blanketing is caused primarily by Ti II. At nebular times, the spectra show strong Ca II lines in the optical (but no [O I] 6300-6364 Å emission), and Ti II in the near-IR. Overall, these results match qualitatively the very disparate properties of .Ia SNe and Ca-rich transients. Although the strong Ti II blanketing and red colours that we predict are rarely observed, they are seen, for example, in OGLE-2013- SN-079. Furthermore, we obtain a faster light-curve evolution than, for example, PTF10iuv, indicating an ejecta mass >0.2 M⊙. An alternate scenario may be the merger of two WDs, one or both composed of He.

  8. Detection of 15NNH+ in L1544: non-LTE modelling of dyazenilium hyperfine line emission and accurate 14N/15N values

    NASA Astrophysics Data System (ADS)

    Bizzocchi, L.; Caselli, P.; Leonardo, E.; Dore, L.

    2013-07-01

    Context. Samples of pristine solar system material found in meteorites and interplanetary dust particles are highly enriched in 15N. Conspicuous nitrogen isotopic anomalies have also been measured in comets, and the 14N/15N abundance ratio of the Earth is itself higher than the recognised presolar value by almost a factor of two. Low-temperature ion/molecule reactions in the proto-solar nebula have been repeatedly indicated as being responsible for these 15N-enhancements. Aims: We have searched for 15N variants of the N2H+ ion in L1544, a prototypical starless cloud core that is one of the best candidate sources for detection owing to its low central core temperature and high CO depletion. The goal is to evaluate accurate and reliable 14N/15N ratio values for this species in the interstellar gas. Methods: A deep integration of the 15NNH+(1-0) line at 90.4 GHz was obtained with the IRAM 30 m telescope. Non-LTE radiative transfer modelling was performed on the J = 1-0 emissions of the parent and 15N-containing dyazenilium ions, using a Bonnor-Ebert sphere as a model for the source. Results: A high-quality fit of the N2H+(1-0) hyperfine spectrum has allowed us to derive a revised value of the N2H+ column density in L1544. Analysis of the observed N15NH+ and 15NNH+ spectra yielded an abundance ratio N(N15NH+)/N(15NNH+) = 1.1 ± 0.3. The obtained 14N/15N isotopic ratio is ~1000 ± 200, suggestive of a sizeable 15N depletion in this molecular ion. Such a result is not consistent with the prediction of the current nitrogen chemical models. Conclusions: Since chemical models predict high 15N fractionation of N2H+, we suggest that 15N14N, or 15N in some other molecular form, tends to deplete onto dust grains. Based on observations carried out with the IRAM 30 m Telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).Full Tables B.1-B.6 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http

  9. Non local thermodynamic equilibrium (LTE) atmospheric limb emission at 4.6 μm: 2. An analysis of the daytime wideband radiances as measured by UARS improved stratospheric and mesospheric sounder

    NASA Astrophysics Data System (ADS)

    López-Puertas, M.; Zaragoza, G.; López-Valverde, M. Á.; Taylor, F. W.

    1998-04-01

    An analysis of the measurements taken by the improved stratospheric and mesospheric sounder (ISAMS) in its carbon monoxide wideband channel around 4.6 μm at daytime is presented. The radiances show a good signal to noise ratio up to the lower thermosphere (about 120 km) and have been shown to be mainly due to emission from the weak CO2 4.3 μm isotopic and hot bands. They exhibit a very clear dependence with the solar illumination at tangent heights above about 60 km, where they have been found to be almost exclusively determined by the solar elevation. Below about 50 km they are dominated by the variations of the kinetic temperature. The measurements have been analyzed in the 50-100 km range by using a detailed non local thermodynamic equilibrium (LTE) model of the CO2 states emitting in the 4.3 μm spectral region and the GENLN2 line-by-line radiance code. A large number (up to 32) of CO2 isotopic and hot bands emit significantly in this spectral region. The N2O(ν3 = 1) and two O3(ν1 + ν3) bands also give contributions in the stratosphere and lower mesosphere. The CO(1→0) band is of relative importance only in the lower thermosphere. The absolute radiances as well as the solar zenith angle dependence are well reproduced by the model. The dependence on the solar zenith angle is due to the absorption of solar radiation in the CO2 near-infrared bands. A sensitivity study of the radiances was also conducted. The major conclusions are (1) the inclusion of the excitation of N2(1) from the electronic energy of O(1D) was required to explain the radiances in the lower mesosphere; (2) the value for the rate of the vibrational exchange between CO2(ν1,ν2,1) and N2(1) is very similar to the laboratory measurements and to that used in the analysis of the Spectral Infrared Rocket Experiment (SPIRE) 4.3 μm CO2 atmospheric limb radiances; and (3) the CO2 volume mixing ratio (vmr) in the 70-100 km region is significantly smaller than that measured in rocket experiments

  10. Non-LTE models for synthetic spectra of type Ia supernovae. III. An accelerated lambda-iteration procedure for the mutual interaction of strong spectral lines in SN Ia models with and without energy deposition

    NASA Astrophysics Data System (ADS)

    Pauldrach, A. W. A.; Hoffmann, T. L.; Hultzsch, P. J. N.

    2014-09-01

    Context. In type Ia supernova (SN Ia) envelopes a huge number of lines of different elements overlap within their thermal Doppler widths, and this problem is exacerbated by the circumstance that up to 20% of these lines can have a line optical depth higher than 1. The stagnation of the lambda iteration in such optically thick cases is one of the fundamental physical problems inherent in the iterative solution of the non-LTE problem, and the failure of a lambda iteration to converge is a point of crucial importance whose physical significance must be understood completely. Aims: We discuss a general problem related to radiative transfer under the physical conditions of supernova ejecta that involves a failure of the usual non-LTE iteration scheme to converge when multiple strong opacities belonging to different physical transitions come together, similar to the well-known situation where convergence is impaired even when only a single process attains high optical depths. The convergence problem is independent of the chosen frequency and depth grid spacing, independent of whether the radiative transfer is solved in the comoving or observer's frame, and independent of whether a common complete-linearization scheme or a conventional accelerated lambda iteration (ALI) is used. The problem appears when all millions of line transitions required for a realistic description of SN Ia envelopes are treated in the frame of a comprehensive non-LTE model. The only solution to this problem is a complete-linearization approach that considers all ions of all elements simultaneously, or an adequate generalization of the established ALI technique that accounts for the mutual interaction of the strong spectral lines of different elements and which thereby unfreezes the "stuck" state of the iteration. Methods: The physics of the atmospheres of SN Ia are strongly affected by the high-velocity expansion of the ejecta, which dominates the formation of the spectra at all wavelength ranges

  11. Effects of new rate constants of transitions from vibrational levels on non-LTE radiation in ro-vibrational bands used for H2O retrieval in the middle atmosphere

    NASA Astrophysics Data System (ADS)

    Manuilova, Rada; Kutepov, Alexander; Feofilov, Artem; Yankovsky, Valentine A.

    populations and limb radiation spectra were calculated using the ALI-ARMS non-LTE code [Kutepov et al. 1998; Feofilov and Kutepov, 2012] for characteristic atmospheric conditions and compared with the populations and spectra obtained for “regular” rate constants used in [Feofilov et al., 2009]. References begin{enumerate} _{}Feofilov A. G., Kutepov A. A., Pesnell W. D., Goldberg R. A., Marshall B. T., Gordley L. L., Garcia-Comas M., Lopez-Puertas M., Manuilova R. O., Yankovsky V. A., Petelina S. V., Russell J. M. III. Daytime SABER/TIMED observations of water vapor in the mesosphere: retrieval approach and first results, Atmospheric Chemistry and Physics, V 9, N 21, P 8139-8158, 2009. _{} Kutepov, A. A., Gusev, O. A., and Ogibalov, V. P., Solution of the non-LTE problem for molecular gas in planetary atmospheres: Superiority of accelerated lambda iteration, J. Quant. Spectrosc. Radiat. Transf. V 60, P 199, 1998. _{} Feofilov, A.G., and Kutepov, A., A., "Infrared Radiation in the Mesosphere and Lower Thermosphere: Energetic Effects and Remote Sensing", Surveys in Geophysics, doi:10.1007/s10712-012-9204-0, (2012).

  12. A Multi-Use Airborne Research Facility

    NASA Technical Reports Server (NTRS)

    Poellot, Michael R.

    2003-01-01

    Much of our progress in understanding the Earth system comes from measurements made in the atmosphere. Aircraft are widely used to collect in situ measurements of the troposphere and lower stratosphere, and they also serve as platforms for many remote sensing instruments. Airborne field measurement campaigns require a capable aircraft, a specially trained support team, a suite of basic instrumentation, space and power for new instruments, and data analysis and processing capabilities (e.g. Veal et al., 1977). However, these capabilities are expensive and there is a need to reduce costs while maintaining the capability to perform this type of research. To this end, NASA entered a Cooperative Agreement with the University of North Dakota (UND) to help support the operations of the UND Cessna Citation research aircraft. This Cooperative Agreement followed in form and substance a previous agreement. The Cooperative Agreement has benefited both NASA and UND. In part because of budget reductions, the NASA Airborne Science Office has elected to take advantage of outside operators of science research platforms to off-load some science requirements (Huning, 1996). UND has worked with NASA to identify those requirements that could be met more cost effectively with the UND platform. This has resulted in significant cost savings to NASA while broadening the base of researchers in the NASA science programs. At the same time, the Agreement has provided much needed support to UND to help sustain the Citation research facility. In this report, we describe the work conducted under this Cooperative Agreement.

  13. Conditional efficient multiuser quantum cryptography network

    NASA Astrophysics Data System (ADS)

    Xue, Peng; Li, Chuan-Feng; Guo, Guang-Can

    2002-02-01

    We propose a conditional quantum key distribution scheme with three nonorthogonal states. Combined with the idea presented by Lo et al. (H.-K. Lo, H. F. Chau, and M. Ardehali, e-print arXiv: quant-ph/0011056), the efficiency of this scheme is increased to tend to 100%. Also, such a refined data analysis guarantees the security of our scheme against the most general eavesdropping strategy. Then, based on the scheme, we present a quantum cryptography network with the addition of a device called ``space optical switch.'' Moreover, we give out a realization of a quantum random number generator. Thus, a feasible experimental scheme of this efficient quantum cryptography network is completely given.

  14. The fast non-LTE code DEDALE

    NASA Astrophysics Data System (ADS)

    Gilleron, Franck; Piron, Robin

    2015-12-01

    We present Dédale, a fast code implementing a simplified non-local-thermodynamic-equilibrium (NLTE) plasma model. In this approach, the stationary collisional-radiative rates equations are solved for a set of well-chosen Layzer complexes in order to determine the ion state populations. The electronic structure is approximated using the screened hydrogenic model (SHM) of More with relativistic corrections. The radiative and collisional cross-sections are based on Kramers and Van Regemorter formula, respectively, which are extrapolated to derive analytical expressions for all the rates. The latter are improved thereafter using Gaunt factors or more accurate tabulated data. Special care is taken for dielectronic rates which are compared and rescaled with quantum calculations from the Averroès code. The emissivity and opacity spectra are calculated under the same assumptions as for the radiative rates, either in a detailed manner by summing the transitions between each pair of complexes, or in a coarser statistical way by summing the one-electron transitions averaged over the complexes. Optionally, nℓ-splitting can be accounted for using a WKB approach in an approximate potential reconstructed analytically from the screened charges. It is also possible to improve the spectra by replacing some transition arrays with more accurate data tabulated using the SCO-RCG or FAC codes. This latter option is particularly useful for K-shell emission spectroscopy. The Dédale code was used to submit neon and tungsten cases in the last NLTE-8 workshop (Santa Fe, November 4-8, 2013). Some of these results are presented, as well as comparisons with Averroès calculations.

  15. Low-bit rate feedback strategies for iterative IA-precoded MIMO-OFDM-based systems.

    PubMed

    Teodoro, Sara; Silva, Adão; Dinis, Rui; Gameiro, Atílio

    2014-01-01

    Interference alignment (IA) is a promising technique that allows high-capacity gains in interference channels, but which requires the knowledge of the channel state information (CSI) for all the system links. We design low-complexity and low-bit rate feedback strategies where a quantized version of some CSI parameters is fed back from the user terminal (UT) to the base station (BS), which shares it with the other BSs through a limited-capacity backhaul network. This information is then used by BSs to perform the overall IA design. With the proposed strategies, we only need to send part of the CSI information, and this can even be sent only once for a set of data blocks transmitted over time-varying channels. These strategies are applied to iterative MMSE-based IA techniques for the downlink of broadband wireless OFDM systems with limited feedback. A new robust iterative IA technique, where channel quantization errors are taken into account in IA design, is also proposed and evaluated. With our proposed strategies, we need a small number of quantization bits to transmit and share the CSI, when comparing with the techniques used in previous works, while allowing performance close to the one obtained with perfect channel knowledge. PMID:24678274

  16. Low-Bit Rate Feedback Strategies for Iterative IA-Precoded MIMO-OFDM-Based Systems

    PubMed Central

    Teodoro, Sara; Silva, Adão; Dinis, Rui; Gameiro, Atílio

    2014-01-01

    Interference alignment (IA) is a promising technique that allows high-capacity gains in interference channels, but which requires the knowledge of the channel state information (CSI) for all the system links. We design low-complexity and low-bit rate feedback strategies where a quantized version of some CSI parameters is fed back from the user terminal (UT) to the base station (BS), which shares it with the other BSs through a limited-capacity backhaul network. This information is then used by BSs to perform the overall IA design. With the proposed strategies, we only need to send part of the CSI information, and this can even be sent only once for a set of data blocks transmitted over time-varying channels. These strategies are applied to iterative MMSE-based IA techniques for the downlink of broadband wireless OFDM systems with limited feedback. A new robust iterative IA technique, where channel quantization errors are taken into account in IA design, is also proposed and evaluated. With our proposed strategies, we need a small number of quantization bits to transmit and share the CSI, when comparing with the techniques used in previous works, while allowing performance close to the one obtained with perfect channel knowledge. PMID:24678274

  17. Facilitating Participation: Teacher Roles in a Multiuser Virtual Learning Environment

    ERIC Educational Resources Information Center

    Wang, Airong

    2015-01-01

    This paper reports on a task-based language teaching course in Second Life. The data set consists of transcribed recordings and a teacher interview. Focusing on how the teacher facilitated student participation, this paper aims to explore the discourse functions in the teacher language output and then to address the teacher roles in three…

  18. Pre-School Equipment for a Multi-Use Center.

    ERIC Educational Resources Information Center

    Stone Mountain Educational Projects Inc., Conway, MA.

    Preschool equipment designed for use in rooms and facilities that are also used for other purposes is described and specifications given. The equipment is portable, inexpensive to make, provides its own storage, adds color to the room, and is durable. Detailed plans and pictures are given for an easel, water table, work bench, appliances in a…

  19. MOOsburg: Multi-User Domain Support for a Community Network.

    ERIC Educational Resources Information Center

    Carroll, John M.; Rosson, Mary Beth; Isenhour, Philip L.; Van Metre, Christina; Schafer, Wendy A.; Ganoe, Craig H.

    2001-01-01

    Explains MOOsburg, a community-oriented MOO that models the geography of the town of Blacksburg, Virginia and is designed to be used by local residents. Highlights include the software architecture; client-server communication; spatial database; user interface; interaction; map-based navigation; application development; and future plans. (LRW)

  20. A multi-user, interactive, annotated flow-chart applet

    SciTech Connect

    Attenberger, S.E.

    1998-10-01

    This paper describes a web-based documentation tool that has been developed for use by a team of collaborators who are developing interacting components within a system. It consists of a Java applet in the form of a flow chart with additional test that can be viewed by clicking on the desired component. The text, positions, and linkages of the components may be edited by the user and saved to the server. The concept could easily be applied to other collaborative work. Using the techniques and code segments described here, a programmer should be able to customize a similar applet for his own use in a few days time.

  1. Mobile Applications and Multi-User Virtual Reality Simulations

    NASA Technical Reports Server (NTRS)

    Gordillo, Orlando Enrique

    2016-01-01

    This is my third internship with NASA and my second one at the Johnson Space Center. I work within the engineering directorate in ER7 (Software Robotics and Simulations Division) at a graphics lab called IGOAL. We are a very well-rounded lab because we have dedicated software developers and dedicated 3D artist, and when you combine the two, what you get is the ability to create many different things such as interactive simulations, 3D models, animations, and mobile applications.

  2. Quantum cryptography on multi-user network architectures

    NASA Astrophysics Data System (ADS)

    Kumavor, Patrick D.; Beal, Alan C.; Yelin, Susanne; Donkor, Eric; Wang, Bing C.

    2006-05-01

    Quantum cryptography applies the uncertainty principle and the no-cloning theorem to allow to parties to share a secret key over an ultra-secure link. Present quantum cryptography technologies provide encryption key distribution only between two users. However, practical implementations of encryption key distribution schemes require establishing secure quantum communications amongst multiple users. This paper looks at some of the advantages and drawbacks of some common network topologies that could be used in sending cryptographic keys across a network consisting of multiple users. These topologies are the star, ring, and bus networks. Their performances are compared and analyzed using quantum bit error rate analysis. The paper also presents an experimental demonstration of a six-user quantum key distribution network implemented on a bus topology.

  3. Cushion system for multi-use child safety seat

    NASA Technical Reports Server (NTRS)

    Dabney, Richard W. (Inventor); Elrod, Susan V. (Inventor)

    2007-01-01

    A cushion system for use with a child safety seat has a plurality of bladders assembled to form a seat cushion that cooperates with the seat's safety harness. One or more sensors coupled to the safety harness sense tension therein and generate a signal indicative of the tension. Each of the bladders is individually pressurized by a pressurization system to define a support configuration of the seat cushion. The pressurization system is disabled when tension in the safety harness has attained a threshold level.

  4. Cushion System for Multi-Use Child Safety Seat

    NASA Technical Reports Server (NTRS)

    Dabney, Richard W. (Inventor); Elrod, Susan V. (Inventor)

    2007-01-01

    A cushion system for use with a child safety seat has a plurality of bladders assembled to form a seat cushion that cooperates with the seat's safety harness. One or more sensors coupled to the safety harness sense tension therein and generate a signal indicative of the tension. Each of the bladders is individually pressurized by a pressurization system to define a support configuration of the seat cushion. The pressurization system is disabled when tension in the safety harness has attained a threshold level.

  5. Gardenification of tropical conserved wildlands: Multitasking, multicropping, and multiusers

    PubMed Central

    Janzen, Daniel

    1999-01-01

    Tropical wildlands and their biodiversity will survive in perpetuity only through their integration into human society. One protocol for integration is to explicitly recognize conserved tropical wildlands as wildland gardens. A major way to facilitate the generation of goods and services by a wildland garden is to generate a public-domain Yellow Pages for its organisms. Such a Yellow Pages is part and parcel of high-quality search-and-delivery from wildland gardens. And, as they and their organisms become better understood, they become higher quality biodiversity storage devices than are large freezers. One obstacle to wildland garden survival is that specific goods and services, such as biodiversity prospecting, lack development protocols that automatically shunt the profits back to the source. Other obstacles are that environmental services contracts have the unappealing trait of asking for the payment of environmental credit card bills and implying delegation of centralized governmental authority to decentralized social structures. Many of the potential conflicts associated with wildland gardens may be reduced by recognizing two sets of social rules for perpetuating biodiversity and ecosystems, one set for the wildland garden and one set for the agroscape. In the former, maintaining wildland biodiversity and ecosystem survival in perpetuity through minimally damaging use is paramount, while in the agroscape, wild biodiversity and ecosystems are tools for a healthy and productive agroecosystem, and the loss of much of the original is acceptable. PMID:10339529

  6. QoS-constrained Energy Minimization in Multiuser Multicarrier Systems

    NASA Astrophysics Data System (ADS)

    Bai, Qing; Ivrlač, Michel T.; Nossek, Josef A.

    In this paper the QoS-constrained resource allocation problem in multicarrier systems is considered. Within the established cross-layer framework, parameters for subchannel assignment, adaptive modulation and coding, and ARQ/HARQ protocols are jointly optimized. Instead of the conventional transmit power minimization, the total energy consumption for the successful transmissions of all information bits is set as the optimization goal. The nonconvex primal problem is solved by using Lagrange dual decomposition and the ellipsoid method. Numerical results indicate that the recovered primal solution is well acceptable in performance, and efficient in terms of computational effort.

  7. HVAC system of the Seavans multi-use complex

    SciTech Connect

    Ishikawa, Masayuki ); Yazawa, Kunio )

    1994-12-01

    This article describes a unique project which features radiant heating and cooling, pressurized smoke control and a cogeneration system. This project, which is located in the Tokyo, Japan waterfront area, has turned a site previously occupied by factory warehouses into an attractive zone with a great deal of water and greenery. Before the project, the site was bordered by a river, a channel and spur railroad tracks. Today, it is a modern urban space complete with such essential infrastructures as roads, bridge, water supply, sewage, and a local HVAC system. The main building consists of two towers--the Seavans South with head-quarters facilities and the Seavans North with rental office spaces--with an atrium (called Amall) in the center. The structure has a plot area of 26,468 m[sup 2] (284,909 ft[sup 2]), and a total floor space of 167,807 m[sup 2] (1,806,319 ft[sup 2]). The Seavans South and North towers are each 24 stores (99 m; 324 ft) high, and both have two penthouses and two levels of basements.

  8. Auction-based Security Game for Multiuser Cooperative Networks

    NASA Astrophysics Data System (ADS)

    Wang, An; Cai, Yueming; Yang, Wendong; Cheng, Yunpeng

    2013-04-01

    In this paper, we develop an auction-based algorithm to allocate the relay power efficiently to improve the system secrecy rate in a cooperative network, where several source-destination pairs and one cooperative relay are involved. On the one hand, the cooperative relay assists these pairs to transmit under a peak power constraint. On the other hand, the relay is untrusty and is also a passive eavesdropper. The whole auction process is completely distributed and no instantaneous channel state information exchange is needed. We also prove the existence and uniqueness of the Nash Equilibrium (NE) for the proposed power auction game. Moreover, the Pareto optimality is also validated. Simulation results show that our proposed auction-based algorithm can effectively improve the system secrecy rate. Besides, the proposed auction-based algorithm can converge to the unique NE point within a finite number of iterations. More interestingly, we also find that the proposed power auction mechanism is cheat-proof.

  9. Handwriting and Gender: A Multi-Use Data Set

    ERIC Educational Resources Information Center

    Bradley, Sean

    2015-01-01

    Can individuals guess the gender of a writer based on a sample of his or her handwriting? We administer an electronic survey twice to the same individuals to find out. The resulting data set is interesting to students, rich enough to be amenable to a wide array of activities, and open to a variety of exploratory tacks for statistics students and…

  10. Multi-User Virtual Environments Fostering Collaboration in Formal Education

    ERIC Educational Resources Information Center

    Di Blas, Nicoletta; Paolini, Paolo

    2014-01-01

    This paper is about how serious games based on MUVEs in formal education can foster collaboration. More specifically, it is about a large case-study with four different programs which took place from 2002 to 2009 and involved more than 9,000 students, aged between 12 and 18, from various nations (18 European countries, Israel and the USA). These…

  11. Optical disk jukebox performance in multi-user applications

    NASA Astrophysics Data System (ADS)

    Hauser, Susan E.; Roy, Gautam; Thoma, George R.

    1994-10-01

    The Lister Hill National Center for Biomedical Communications, a research and development division of the National Library of Medicine, is evaluating an optical disk jukebox as a digital image store to support prototype systems for image distribution over the Internet. This paper summarizes a study undertaken to determine the performance characteristics of the jukebox to support multiple image databases simultaneously accessed by multiple users. A motivation for this investigation is the need to provide users access to digitized images of medical documents and radiographs.

  12. Interference coordination of heterogeneous LTE systems using remote radio heads

    NASA Astrophysics Data System (ADS)

    Kim, Jaewon; Lee, Donghyun; Sung, Wonjin

    2013-12-01

    In this paper, we present an operational strategy to mitigate co-channel interference (CCI) by using geographically distributed remote radio heads (RRHs). The inter-node CCI becomes a dominant performance degradation factor for heterogeneous network (HetNet) systems. Recently, there are emerging attempts in Third Generation Partnership Project to adopt advanced techniques to Long Term Evolution Advanced systems to mitigate CCI problems for HetNet systems, namely, the coordinated multipoint transmission (CoMP). However, the CoMP scheme cannot control the CCI generated from outside coordination boundaries. To resolve this problem, we propose a partial activation strategy by using RRHs deployed near cell edge which results in moving coverage boundary effects. Based on Monte Carlo system level simulations, performance of the conventional strategies and the presented strategy is evaluated. Simulation results show that the proposed scheme outperforms the enhanced inter-cell interference coordination and CoMP schemes especially for users located near cell edge areas.

  13. Non-LTE Equation of State for ICF simulations

    NASA Astrophysics Data System (ADS)

    Klapisch, Marcel; Bar-Shalom, Avraham; Colombant, Denis

    2002-11-01

    SCROLL is a collisional radiative model able to deal with complex spectra[1]. It is used to generate opacity/emissivity databases [2] compatible with the hydrocode FAST[3] for all elements of interest in the simulation of ICF targets, including high-Z. It is now modified to yield tables of EOS data for FAST, in the whole range of interest (T=1 to 25000eV, rho=10-6 to 100g/cc). SCROLL contributes the electronic -free and bound- part of the EOS, replacing Busquet's model of an ionization temperature. Ionization energies include contributions of all excited states. Energies and Z* go smoothly to the high density regime, where a "jellium" model is assumed. The free electrons are self consistent with the bound electrons. Examples of runs will be shown. Supported by USDOE through a contract with the Naval Research Laboratory. [1] A. Bar-Shalom, J. Oreg, and M. Klapisch, J. Quant. Spectrosc. Radiat. Transfer 65, 43 (2000). [2] A. Bar-shalom, M. Klapisch, J. Oreg, and D. Colombant, Bull. Am. Phys. Soc. 46, 295 (2001). [3] J. H. Gardner, A. J. Schmitt, J. P. Dahlburg, et al, Phys. Plasmas 5, 1935 (1998).

  14. Intrinsic interference mitigating coordinated beamforming for the FBMC/OQAM based downlink

    NASA Astrophysics Data System (ADS)

    Cheng, Yao; Li, Peng; Haardt, Martin

    2014-12-01

    In this work, we propose intrinsic interference mitigating coordinated beamforming (IIM-CBF)-based transmission strategies for the downlink of multi-user multiple-input-multiple-out (MIMO) systems and coordinated multi-point (CoMP) systems where filter bank based multi-carrier with offset quadrature amplitude modulation (FBMC/OQAM) is employed. Our goal is to alleviate the dimensionality constraint imposed on the state-of-the-art solutions for FBMC/OQAM-based space division multiple access that the total number of receive antennas of the users must not exceed the number of transmit antennas at the base station. First, two IIM-CBF algorithms are developed for a single-cell multi-user MIMO downlink system. The central idea is to jointly and iteratively calculate the precoding matrix and decoding matrix for each subcarrier to mitigate the multi-user interference as well as the intrinsic interference inherent in FBMC/OQAM-based systems. Second, for a CoMP downlink scenario where partial coordination among the base stations is considered, the application of coordinated beamforming-based transmission schemes is further investigated. An appropriate IIM-CBF technique is proposed. Simulation results show that when the number of transmit antennas at the base station is equal to the total number of receive antennas of the users, the proposed IIM-CBF algorithm outperforms the existing transmission strategies for FBMC/OQAM-based multi-user MIMO downlink systems. Moreover, we evaluate the performances of the IIM-CBF schemes in the downlink of multi-user MIMO systems and CoMP systems where the total number of receive antennas of users exceeds the number of transmit antennas at the base station. It is observed that by employing the IIM-CBF techniques, FBMC/OQAM systems achieve a similar bit error rate (BER) performance as its orthogonal frequency division multiplexing with the cyclic prefix insertion (CP-OFDM)-based counterpart while exhibiting superiority in terms of a higher

  15. Spectral-temporal-polarization encoding of photons for multi-user secure quantum communication

    NASA Astrophysics Data System (ADS)

    Donkor, Eric

    2014-05-01

    We describe a Quantum Key Distribution protocol that combines temporal-, spectraland polarization-encoding of photons for secure communication over an interconnected network of users. Temporal encoding is used to identify a user's location or address on the network. Polarization encoding is used to generate private cryptographic key. Polarization encoded information is locally and randomly generated by users and exchanged only over a dedicated secure channel. Spectral encoding allows for the detection of eavesdropping and tampering by a malicious agent. Temporal-spectral signals sent from the network administrator (Alice) to a user are bright light source. On the other hand spectral-temporal signal from a network user (Bob) to the administrator (Alice) are single photons. Signals are sent across the network as ordered light pairs. The ordering format is randomly chosen and are revealed only at the time of key selection between the parties so that a secure one-time cryptographic pad can be generated

  16. The convergence of neomillennial learning styles and a multi-user virtual environment

    NASA Astrophysics Data System (ADS)

    Dieterle, Edward Robert, II

    Learning styles influenced and cultivated by immersive technologies have spawned a new area of research, "neomillennial" learning styles (NLS). The present study utilizes a quantitative approach, including principal components analysis and multiple regression/correlation analysis, to investigate NLS. Evidence supporting the arguments laid out in this study derives from a sample of 574 middle grades students from urban, suburban, and rural school settings in North America that participated in the River City Project (RCP) in academic year 2006-07. Central to RCP is an immersive simulation for teaching inquiry-based science and 21st century skills, where success is measured across five dimensions: (a) collaboration, (b) science content understanding, (c) self-efficacy in science, (d) self-efficacy in scientific inquiry, and (e) thoughtfulness of inquiry. Besides taking part in RCP, participating students completed an instrument that generates a profile of their NLS. The resulting profile includes measures of students' fluency in multiple media; the extent to which they prefer learning based on collectively seeking, sieving, and synthesizing experiences; and their tendency toward expression through webs of representations. This study revealed that, on average, a student who prefers: (1) engaging tasks that require creative strategies and seeing and doing things in new ways, while avoiding tasks that involve details, is well suited for learning disease transmission and the scientific method in RCP; (2) distributing attention across multiple tasks that have been prioritized will further his or her belief in their ability to do science by participating via RCP whereas the same conditions may undercut a student who avoids distributing attention across multiple tasks that have been prioritized; (3) to read books, magazines, and newspapers by choice and who score high on measures of their general connectedness with the media is well suited for increasing his or her belief in their ability to complete activities common to practicing scientists in RCP; and (4) (a) engaging tasks that require creative strategies, (b) seeing and doing things in new ways, and (c) distributing attention across multiple tasks that have been prioritized is well suited for increasing his or her use of inquiry and reflection when performing science-related activities in RCP.

  17. A Browser-Based Multi-User Working Environment for Physicists

    NASA Astrophysics Data System (ADS)

    Erdmann, M.; Fischer, R.; Glaser, C.; Klingebiel, D.; Komm, M.; Müller, G.; Rieger, M.; Steggemann, J.; Urban, M.; Winchen, T.

    2014-06-01

    Many programs in experimental particle physics do not yet have a graphical interface, or demand strong platform and software requirements. With the most recent development of the VISPA project, we provide graphical interfaces to existing software programs and access to multiple computing clusters through standard web browsers. The scalable clientserver system allows analyses to be performed in sizable teams, and disburdens the individual physicist from installing and maintaining a software environment. The VISPA graphical interfaces are implemented in HTML, JavaScript and extensions to the Python webserver. The webserver uses SSH and RPC to access user data, code and processes on remote sites. As example applications we present graphical interfaces for steering the reconstruction framework OFFLINE of the Pierre-Auger experiment, and the analysis development toolkit PXL. The browser based VISPA system was field-tested in biweekly homework of a third year physics course by more than 100 students. We discuss the system deployment and the evaluation by the students.

  18. A scalable distributed paradigm for multi-user interaction with tiled rear projection display walls.

    PubMed

    Roman, Pablo; Lazarov, Maxim; Majumder, Aditi

    2010-01-01

    We present the first distributed paradigm for multiple users to interact simultaneously with large tiled rear projection display walls. Unlike earlier works, our paradigm allows easy scalability across different applications, interaction modalities, displays and users. The novelty of the design lies in its distributed nature allowing well-compartmented, application independent, and application specific modules. This enables adapting to different 2D applications and interaction modalities easily by changing a few application specific modules. We demonstrate four challenging 2D applications on a nine projector display to demonstrate the application scalability of our method: map visualization, virtual graffiti, virtual bulletin board and an emergency management system. We demonstrate the scalability of our method to multiple interaction modalities by showing both gesture-based and laser-based user interfaces. Finally, we improve earlier distributed methods to register multiple projectors. Previous works need multiple patterns to identify the neighbors, the configuration of the display and the registration across multiple projectors in logarithmic time with respect to the number of projectors in the display. We propose a new approach that achieves this using a single pattern based on specially augmented QR codes in constant time. Further, previous distributed registration algorithms are prone to large misregistrations. We propose a novel radially cascading geometric registration technique that yields significantly better accuracy. Thus, our improvements allow a significantly more efficient and accurate technique for distributed self-registration of multi-projector display walls. PMID:20975205

  19. Copper sulfate is an effective, economical, multi-use compound for fish

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Copper sulfate has a long and storied history of use in aquaculture. Copper sulfate also has a wide range of uses including aquatic weed control, snail control, and treating fish diseases. A number of studies have been conducted to show copper sulfate efficacy against diseases including columnaris d...

  20. Application areas of multi-user virtual environments in the healthcare context.

    PubMed

    Ghanbarzadeh, Reza; Ghapanchi, Amir Hossein; Blumenstein, Michael

    2014-01-01

    This study conducts a systematic literature review on the application of the three-dimensional virtual worlds (3DVW) in healthcare context. During the past decade, 3DVWs have emerged as a cutting edge technology that has much to offer to the healthcare sector. Our systematic review began with an initial set of 1088 studies published from 1990 to 2013 which have used 3DVWs for the healthcare specific purposes. We found a variety of areas of application for the 3DVWs in healthcare, and categorised them into the following categories: education, treatment, evaluation, lifestyle and simulation. The presented big picture of application areas of 3DVWs in this study can be very valuable and insightful for the researchers and healthcare community. PMID:25087525

  1. All-optical binary phase-coded UWB signal generation for multi-user UWB communications.

    PubMed

    Dong, Jianji; Yu, Yuan; Zhang, Yin; Li, Xiang; Huang, Dexiu; Zhang, Xinliang

    2011-05-23

    An all-optical incoherent scheme for generation of binary phase-coded ultra-wideband (UWB) signals is proposed and experimentally demonstrated. The binary phase coding is performed based on all-optical phase modulation in a semiconductor optical amplifier (SOA) and phase modulation to intensity modulation (PM-IM) conversion in a fiber delay interferometer (DI) that serves as a multichannel frequency discriminator. By locating the phase-modulated light waves at the positive and negative slopes of the DI transmission spectra, binary phase encoded UWB codes (0 and π) are generated. We also experimentally demonstrate a bipolar UWB coding system with a code length of 4, operating at 1.25 Gb/s. And the decoding is analyzed as well. Our proposed system has potential application in future high-speed UWB impulse radio over optical fiber access networks. PMID:21643312

  2. ADAPTIVE MANAGEMENT FOR IMPROVED WATER QUALITY IN MULTI-USE WATERSHEDS

    EPA Science Inventory

    This project will develop a management plan for eliminating nuisance algal blooms in a chain of reservoirs along the Huron River in southeastern Michigan. The river-reservoir system is used for municipal drinking water, wastewater disposal, irrigation, industrial p...

  3. Cryptanalysis and Improvement of the Multi-User QPCE Protocol with Semi-Honest Third Party

    NASA Astrophysics Data System (ADS)

    Chang, Yan; Xu, Chun-Xiang; Zhang, Shi-Bin; Wang, Hai-Chun; Yan, Li-Li; Han, Gui-Hua; Huang, Yuan-Yuan; Sheng, Zhi-Wei

    2016-01-01

    Not Available Supported by the National Natural Science Foundation of China under Grant Nos 61402058, 61572086 and 61370203, the Fund for Middle and Young Academic Leaders of Chengdu University of Information Technology under Grant No J201511, the Science and Technology Support Project of Sichuan Province under Grant No 2013GZX0137, the Fund for Young Persons Project of Sichuan Province under Grant No 12ZB017, and the Foundation of Cyberspace Security Key Laboratory of Sichuan Higher Education Institutions under Grant No szjj2014-074.

  4. Design method for multi-user workstations utilizing anthropometry and preference data.

    PubMed

    Mahoney, Joseph M; Kurczewski, Nicolas A; Froede, Erick W

    2015-01-01

    Past efforts have been made to design single-user workstations to accommodate users' anthropometric and preference distributions. However, there is a lack of methods for designing workstations for group interaction. This paper introduces a method for sizing workstations to allow for a personal work area for each user and a shared space for adjacent users. We first create a virtual population with the same anthropometric and preference distributions as an intended demographic of college-aged students. Members of the virtual population are randomly paired to test if their extended reaches overlap but their normal reaches do not. This process is repeated in a Monte Carlo simulation to estimate the total percentage of groups in the population that will be accommodated for a workstation size. We apply our method to two test cases: in the first, we size polygonal workstations for two populations and, in the second, we dimension circular workstations for different group sizes. PMID:25048681

  5. Developing Simulations in Multi-User Virtual Environments to Enhance Healthcare Education

    ERIC Educational Resources Information Center

    Rogers, Luke

    2011-01-01

    Computer-based clinical simulations are a powerful teaching and learning tool because of their ability to expand healthcare students' clinical experience by providing practice-based learning. Despite the benefits of traditional computer-based clinical simulations, there are significant issues that arise when incorporating them into a flexible,…

  6. The Lawrence Livermore National Laboratory (LLNL) multi-user Tandem Laboratory

    SciTech Connect

    Davis, J.C.

    1988-09-01

    An FN tandem laboratory, cofounded by several Lawrence Livermore National Laboratory Divisions, Sandia Livermore, and the University of California Regents, is now operational at Livermore. The accelerator, formerly the University of Washington injector, has been upgraded with SF/sub 6/, Dowlish tubes, and a NEC pelletron charging system. A conventional duoplasmatron, a tritium source, and two Cs sputtering sources will be fielded on the accelerator. Pulsed beams will be available from two source positions. The laboratory has been designed to accommodate up to 19 experimental positions with excellent optics and working vacuum. The facility is unshielded with both accelerator and radiological systems under the control of a distributed microprocessor system. Research activities at the tandem include nuclear physics and astrophysics, materials science and characterization programs, and accelerator mass spectrometry for archaeology, biomedical, environmental and geoscience investigators. 3 refs., 1 fig.

  7. PLAN AND CONCEPTS FOR MULTI-USE MANAGEMENT OF THE ATCHAFALAYA BASIN

    EPA Science Inventory

    The report determines surface water requirements of the natural resource complex, including fishes, wildlife, and forests, and the socio-economic resource uses, including flood control, urban and industrial development, mineral extraction, transportation, agriculture, and recreat...

  8. Immersive Collaboration Simulations: Multi-User Virtual Environments and Augmented Realities

    NASA Technical Reports Server (NTRS)

    Dede, Chris

    2008-01-01

    Emerging information technologies are reshaping the following: shifts in the knowledge and skills society values, development of new methods of teaching and learning, and changes in the characteristics of learning.

  9. The Role of Environment Design in an Educational Multi-User Virtual Environment

    ERIC Educational Resources Information Center

    Papachristos, Nikiforos M.; Vrellis, Ioannis; Natsis, Antonis; Mikropoulos, Tassos A.

    2014-01-01

    This paper presents empirical results from an exploratory study conducted in an authentic educational situation with preservice education students enrolled in an undergraduate course, which was partially taught in Second Life. The study investigated the effect of environment design on presence, learning outcomes and the overall experience of the…

  10. Design on the MUVE: Synergizing Online Design Education with Multi-User Virtual Environments (MUVE)

    ERIC Educational Resources Information Center

    Sakalli, Isinsu; Chung, WonJoon

    2015-01-01

    The world is becoming increasingly virtual. Since the invention of the World Wide Web, information and human interaction has been transferring to the web at a rapid rate. Education is one of the many institutions that is taking advantage of accessing large numbers of people globally through computers. While this can be a simpler task for…

  11. Towards improved biomonitoring tools for an intensified sustainable multi-use environment.

    PubMed

    van der Meer, Jan Roelof

    2016-09-01

    The increasing use of our environment for multiple contrasting activities (e.g. fisheries, tourism) will have to be accompanied by improved monitoring of environmental quality, to avoid transboundary conflicts and ensure long-term sustainable intensified usage. Biomonitoring approaches are appropriate for this, since they can integrate biological effects of environmental exposure rather than measure individual compound concentrations. Recent advances in biomonitoring concepts and tools focus on single-cell assays and purified biological components that can be miniaturized and integrated in automated systems. Despite these advances, we are still very far from being able to deploy bioassays routinely in environmental monitoring, mostly because of lack of experience in interpreting responses and insufficient robustness of the biosensors for their environmental application. Further future challenges include broadening the spectrum of detectable compounds by biosensors, accelerate response times and combining sample pretreatment strategies with bioassays. PMID:27468753

  12. Digital Literacies in Multiuser Virtual Environments among College-Level Developmental Readers

    ERIC Educational Resources Information Center

    Burgess, Melissa L.; Price, Debra P.; Caverly, David C.

    2012-01-01

    As the rate of developmental reading students continues to climb, so does the surge in digital platforms as a means to deliver postsecondary instruction. Students enrolled in developmental reading courses should not be assumed to have digital literacy skills simply because they have been termed a "digitally literate generation." In this study, one…

  13. The Light Microscopy Module: An On-Orbit Multi-User Microscope Facility

    NASA Technical Reports Server (NTRS)

    Motil, Susan M.; Snead, John H.

    2002-01-01

    The Light Microscopy Module (LMM) is planned as a remotely controllable on-orbit microscope subrack facility, allowing flexible scheduling and operation of fluids and biology experiments within the Fluids and Combustion Facility (FCF) Fluids Integrated Rack (FIR) on the International Space Station (ISS). The LMM will be the first integrated payload with the FIR to conduct four fluid physics experiments. A description of the LMM diagnostic capabilities, including video microscopy, interferometry, laser tweezers, confocal, and spectrophotometry, will be provided.

  14. HYDRAULICS OF THE ATCHAFALAYA BASIN MAIN CHANNEL SYSTEM: CONSIDERATIONS FROM A MULTIUSE MANAGEMENT STANDPOINT

    EPA Science Inventory

    The report examines the relationships among hydraulic elements in the Atchafalaya Basin floodway system in terms of discharge regime, sediment load, channel form and size, flood control, water surface slope, bank elevation, overbank capacity, dredging requirements, and spoil disp...

  15. A New Step Towards the "Stratobus Idea": A Modular Pivot for Multiuser Platform

    NASA Astrophysics Data System (ADS)

    Boscaleri, A.; Fiorineschi, L.; Rissone, P.; Baldi, M.

    2015-09-01

    The pivot is a strategic part of stratospheric flights. It suspends all the experiments that need spinning in the azimuth coordinate in order to point at given sky targets independently of any random rotation of the balloon. In pursuing the STRATOBUS idea, like many other payload parts also the pivot has undergone considerable modifications as compared with its earlier design. Indeed, the goal is to optimize those parts that are capable of reducing campaign costs, thus making possible more frequent flights beyond the atmosphere. To be more precise, the said modifications have been focused on obtaining versatile mechanical parts that can be recovered after landing and then reused in many different flight configurations. As far as the pivot is concerned, the development of this new concept has been carried out by taking into account the advantages provided by modular architecture. However, all the functionalities of the previous design have been maintained.

  16. Learning Embedded Software Design in an Open 3A Multiuser Laboratory

    ERIC Educational Resources Information Center

    Shih, Chien-Chou; Hwang, Lain-Jinn

    2011-01-01

    The need for professional programmers in embedded applications has become critical for industry growth. This need has increased the popularity of embedded software design courses, which are resource-intensive and space-limited in traditional real lab-based instruction. To overcome geographic and time barriers in enhancing practical skills that…

  17. Well completion technology. Multiuse polymer protects injection well during drilling, underreaming, gravel packing

    SciTech Connect

    Davis, K.E.; Jarrell, M.D.

    1983-12-12

    Fluids for drilling, gravel-packing, and completion were optimized for an expensive injection well. Successful engineering gave maximum injection rates and no skin damage, while accomplishing all the fundamental drilling and suspension functions of fluids. Formation protection was critical. The approximately $5-million well was planned for chemical waste disposal, and plant capacity is limited by injectivity. This work describes the fluid, hardware, and techniques used. The 3 distinct fluids were variations on the same polymer-based system. Results of tests showed that Kelzan XCD Polymer, a dispersible form of xanthan gum, had the most applicable overall properties.

  18. The Development of Mathematical Argumentation in an Unmoderated, Asynchronous Multi-User Dynamic Geometry Environment

    ERIC Educational Resources Information Center

    Fukawa-Connelly, Tim; Silverman, Jason

    2015-01-01

    This paper explores student interactions from the Virtual Math Teams-With-GeoGebra Project, a computer-supported collaborative learning environment that allows individuals to interact, collaborate, and discuss user-created dynamic mathematics objects. Previous studies of virtual math teams have focused on the coconstruction of a joint problem…

  19. Ficus elastica-The Indian rubber tree-an underutilized promising multi-use species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ficus elastica known as the Indian rubber tree has a white, milky latex that is a source of natural rubber was analyzed for its phytochemicals as an intermediate energy source. The tree produces a high quantity of protein and oil (24.5 and 6.1% respectively). The polyphenol content was 4.2%, and hyd...

  20. A multi-user carrier structure for deploying Pegasus-launched micro-satellites

    NASA Astrophysics Data System (ADS)

    King, J. A.; Beidleman, N. J.; Stoltz, P. M.

    A concept has been developed to place multiple microsatellites into different orbits utilizing a single Pegasus launch vehicle. This approach uses separable pallets with each having an integral propulsion system that can transport from one to six microsatellites into an orbit modified from the reference orbit provided by the launch vehicle. The propulsion and mechanical system designs are described and the capability of the Pegasus is discussed as it impacts the individual microsatellite payload mass. Examples are provided as to how the system can be employed to implement different mission options. It is shown that when a constellation of communications satellites is deployed by this method, global coverage may be provided at what is thought to be the lowest cost available today.

  1. HSTDEK: Developing a methodology for construction of large-scale, multi-use knowledge bases

    NASA Technical Reports Server (NTRS)

    Freeman, Michael S.

    1987-01-01

    The primary research objectives of the Hubble Space Telescope Design/Engineering Knowledgebase (HSTDEK) are to develop a methodology for constructing and maintaining large scale knowledge bases which can be used to support multiple applications. To insure the validity of its results, this research is being persued in the context of a real world system, the Hubble Space Telescope. The HSTDEK objectives are described in detail. The history and motivation of the project are briefly described. The technical challenges faced by the project are outlined.

  2. The Affordance of Online Multiuser Virtual Environments (MUVE) for Creative Collaboration

    ERIC Educational Resources Information Center

    Hong, Seung Wan

    2013-01-01

    Creativity is an important criterion for evaluating conceptual and design abilities of architects and their praxis. However, in recent years, the world has grown more complex. New problems have emerged that are often outside the architect's capacity. Given this challenge, architects collaborate with colleagues from architecture and other related…

  3. Cooperative multi-user detection and ranging based on pseudo-random codes

    NASA Astrophysics Data System (ADS)

    Morhart, C.; Biebl, E. M.

    2009-05-01

    We present an improved approach for a Round Trip Time of Flight distance measurement system. The system is intended for the usage in a cooperative localisation system for automotive applications. Therefore, it is designed to address a large number of communication partners per measurement cycle. By using coded signals in a time divison multiple access order, we can detect a large number of pedestrian sensors with just one car sensor. We achieve this by using very short transmit bursts in combination with a real time correlation algorithm. Futhermore, the correlation approach offers real time data, concerning the time of arrival, that can serve as a trigger impulse for other comunication systems. The distance accuracy of the correlation result was further increased by adding a fourier interpolation filter. The system performance was checked with a prototype at 2.4 GHz. We reached a distance measurement accuracy of 12 cm at a range up to 450 m.

  4. Computational model for non-LTE atomic process in laser produced plasmas

    NASA Astrophysics Data System (ADS)

    Takabe, Hideaki; Nishikawa, Takeshi

    1994-02-01

    A computational model for simulating hydro-radiation phenomena has been studied relating to the partially ionized gold plasma produced by irradiation of intense laser light. The screened hydrogenic model with l-splitting effect and the average ion model are used to determine the atomic state of gold ions in the collisional radiative equilibrium. A statistical method is used to evaluate the spectral opacity and emissivity due to the clusters of line transitions. The x-ray conversion rate and spectrum calculated with the hydrodynamic code ILESTA coupled with opacity and emissivity are compared with those observed experimentally.

  5. A spherical, non-LTE, blanketed model stellar atmosphere for Phi CAS (FOIa)

    NASA Astrophysics Data System (ADS)

    Rosenzweig, Patricia

    By constructing a model atmosphere, the theoretical energy distribution of the emergent radiation that best matches the observed energy distribution of the star Phi Cassiopeiae is calculated; its effective temperature and surface gravity are thus derived. In order to use the pair method to derive the extinction curve for NGC 457 of which Phi Cas is a member, a new method is developed for choosing a lightly reddened comparison star, which consists of matching the equivalent widths of spectral features that are particularly strong and sensitive to temperature and luminosity. The intrinsic energy distribution of Phi Cas was determined from 1500 to 5800 A. A detailed new spherical model atmosphere was constructed. The equation of transfer was solved with the constraints of hydrostatic and pure radiative equilibrium. The statistical equilibrium of 10 to the 6th transitions was treated. Several tests have demonstrated this model to be reliable. Results imply a mass of 6.3 + or - 3.6 solar masses, which agrees with the mass of the main-sequence turnoff of NGC 457.

  6. Spherical, non-LTE, blanketed model stellar atmosphere for Phi Cas (FOIa)

    SciTech Connect

    Rosenzweig, P.

    1987-01-01

    By constructing a model atmosphere, the author calculated the theoretical energy distribution of the emergent radiation that best matches the observed energy distribution of the star Phi Cas, and so derived its effective temperature and surface gravity. For an accurate comparison between theory and observations, it is desirable to determine the interstellar extinction in situ and then correct the observations for it. Fortunately, Phi Cas is very likely a member of the open cluster NGC 457. Five early B-type stars near the main-sequence turnoff in NGC 457 were observed at low dispersion with the IUE satellite. In order to use the pair method to derive the extinction curve for NGC 457, a new method of choosing a lightly reddened comparison star is developed. It consists of matching the equivalent widths of spectral features that are particularly strong and sensitive to temperature and luminosity. The UV extinction in NGC 457 deviates from the average extinction for the Milky way and is uniform across the cluster. For the visible region, monochromatic fluxes of Phi Cas were dereddened with a mean extinction curve. Thus, the intrinsic energy distribution of Phi Cas was determined from 1500 to 5800 (Angstrom symbol).

  7. Observations, analysis and interpretation with non-LTE of chromospheric structures of the Sun

    NASA Astrophysics Data System (ADS)

    Sánchez-Andrade Nuño, Bruno

    2009-02-01

    This thesis is based on observations performed at the Vacuum Tower Telescope (Tenerife). We have used an infrared spectropolarimeter (TIP) and a Fabry-Perot spectrometer (G-FPI) from years 2004 to 2006. We have applied several imaging speckle reconstruction techniques, and compared them. We have studied chromospheric dynamics inside the solar disc and at the limb using Halpha with very high spatial, spectral and temporal resolution. Keywords (see full abstract for details): fibrils, surge, MHD waves, speckle, blind deconvolution, Fabry-Perot, mini-flares, cloud model, spicules in Halpha, spicules continuing on the disc) Using He I 10830 we studied the offlimb spicular spectral I profiles with height over the limb. The analysis shows the variation of the off-limb emission profiles as a function of the distance to the visible solar limb. The intensity ratio of the multiplet (which is related to the optical thickness and coronal irradiation) is studied and compared with standard atmospheric models. We report observational properties from high-resolution filtergrams in the Halpha spectral line taken with the G-FPI. We find that spicules can reach heights of 8 Mm above the limb. We show that spicules outside the limb continue as dark fibrils inside the disc.

  8. High Accuracy Non-LTE Modeling of X-Ray Radiation in Dense Matter

    NASA Astrophysics Data System (ADS)

    Dasgupta, Arati; Clark, Robert W.; Giuliani, John L.; Thornhill, Ward J.; Apruzese, John P.; Jones, Brent; Ampleford, Dave J.

    X-rays are emitted from a variety of astrophysical objects in the universe. With the advancement of experimental technologies, intense and very bright X-ray sources are also being produced in the laboratory. Similar progress in theoretical investigations has made it possible to accurately model the radiation and spectroscopy of X-rays from both laboratory and astrophysical sources. Present-day Z-pinch experiments generate 200 TW peak power, 5-10 ns duration X-ray bursts that provide new opportunities to advance radiation science. The experiments spotlight the underlying atomic and plasma physics and offer inertial confinement fusion and astrophysics applications. Spectroscopy is a key diagnostic tool and its reliability depends on the accuracy and reliability of the atomic and plasma physics models used to interpret the data. We report the current status of our theoretical investigations of X-ray spectroscopy using state-of-the-art atomic and plasma modeling to analyze the data obtained from Z machine at the US Sandia National Laboratories. Analysis used for Z-pinches can also be used to study ICF and astrophysical plasmas where laboratory measurements and simulations are the only means to interpret observed data.

  9. A 6th order wideband active-RC LPF for LTE application

    NASA Astrophysics Data System (ADS)

    Baoyue, Wei; Hongkun, Li; Yunfeng, Wang; Haiying, Zhang

    2012-06-01

    A low power, highly linear active-RC filter is presented. This filter is synthesized from a low pass 6 order Chebyshev RLC ladder, and exhibits a reconfigurable bandwidth (10 MHz, 50 MHz). In order to meet the high cutoff frequency (50 MHz) and strict adjacent channel rejection requirements, a novel operational amplifier based on a new compensation technique is used, which optimizes high frequency filter performance and minimizes current consumption. This filter is fabricated in a 0.18 μm CMOS process, the measurement results indicate that the filter provides 10 MHz and 50 MHz selectable bandwidth, and excellent adjacent channel rejection: -15.3 dB at 12.5 MHz with 10 MHz cutoff frequency, -8.3 dB at 60 MHz with 50 MHz cutoff frequency, three times out-band rejection more than 60 dB while the in-band ripple is less than 1 dB.

  10. Prominence fine-structure dynamics as inferred from 2D non-LTE models

    NASA Astrophysics Data System (ADS)

    Gunar, Stanislav; Schmieder, Brigitte; Mein, Pierre; Heinzel, Petr

    2012-07-01

    2D multi-thread prominence fine structure models are able to produce synthetic Lyman spectra in very good agreement with spectral observations by SOHO/SUMER including the spectral line asymmetries. The synthetic differential emission measure curves derived from these models are also in a good agreement with observations. Now we show that these models are also able to produce synthetic H-alpha line profiles in very good agreement with observations which allows us to analyze not only the physical parameters of the prominence fine-structure plasma but also some aspects of its dynamical behaviour. We compare the synthetic H-alpha spectra with the observed spectra of the April 26, 2007 prominence using three statistical parameters: the line integrated intensity, the line full-width at the half-maximum (FWHM), and the Doppler velocity derived from shifts of the line profiles. This statistical analysis allows us to conclude that the overall statistical distribution of the LOS velocities in the April 26, 2007 prominence at the time of the observations was below +/-15 km/s and in the prominence core was close to +/-10 km/s. In combination with the analysis of the Lyman spectra we determine several physical parameters of the observed prominence fine structures which show that the April 26, 2007 prominence was relatively less massive. We are also able to put some constrains on the prominence core temperature that might be relatively low, reaching values below 6000 K.

  11. Non-LTE modelling of prominence fine structures using hydrogen Lyman-line profiles

    NASA Astrophysics Data System (ADS)

    Schwartz, P.; Gunár, S.; Curdt, W.

    2015-05-01

    Aims: We perform a detailed statistical analysis of the spectral Lyman-line observations of the quiescent prominence observed on May 18, 2005. Methods: We used a profile-to-profile comparison of the synthetic Lyman spectra obtained by 2D single-thread prominence fine-structure model as a starting point for a full statistical analysis of the observed Lyman spectra. We employed 2D multi-thread fine-structure models with random positions and line-of-sight velocities of each thread to obtain a statistically significant set of synthetic Lyman-line profiles. We used for the first time multi-thread models composed of non-identical threads and viewed at line-of-sight angles different from perpendicular to the magnetic field. Results: We investigated the plasma properties of the prominence observed with the SoHO/SUMER spectrograph on May 18, 2005 by comparing the histograms of three statistical parameters characterizing the properties of the synthetic and observed line profiles. In this way, the integrated intensity, Lyman decrement ratio, and the ratio of intensity at the central reversal to the average intensity of peaks provided insight into the column mass and the central temperature of the prominence fine structures.

  12. Non-LTE line formation in clumpy and turbulent molecular clouds

    NASA Astrophysics Data System (ADS)

    Hegmann, M.; Kegel, W. H.

    2000-07-01

    Extending previous work (Albrecht & Kegel \\cite{alb87}, Kegel et al. \\cite{keg93}, Piehler & Kegel \\cite{pie94}), we investigated the formation of interstellar molecular lines in a medium with stochastic density and velocity fluctuations. We solved the full NLTE-problem, i.e. the generalized radiative transfer equation simultaneously with the rate equations, for a 6-level CO molecule and a plane-parallel slab geometry. Our results indicate that accounting for a finite correlation length of both, the density and velocity field, strongly affects the line profile and the line width as well as the intensity ratios of different rotational transitions.

  13. On-the-field performance of quintuple-play long-reach OFDM-based WDM-PON optical access networks.

    PubMed

    Llorente, Roberto; Morant, Maria; Pellicer, Eloy; Herman, Milan; Nagy, Zsolt; Alves, Tiago; Cartaxo, Adolfo; Herrera, Javier; Correcher, Jose; Quinlan, Terence; Walker, Stuart; Rodrigues, Cláudio; Cluzeaud, Pierre; Schmidt, Axel; Piesiewicz, Radoslaw; Sambaraju, Rakesh

    2014-03-24

    In this paper the on-the-field performance of a WDM-PON optical access providing quintuple-play services using orthogonal frequency division multiplexing (OFDM) modulation is evaluated in a real fiber-to-the-home (FTTH) network deployed by Towercom operator in Bratislava (Slovakia). A bundle of quintuple-play services comprising full-standard OFDM-based signals (LTE, WiMAX, UWB and DVB-T) and an ad-hoc OFDM-GbE signal is transmitted in coexistence per single user. Both downstream and upstream transmission performances are evaluated in different on-the-field long-reach optical link distance configurations. Four wavelength multi-user transmission of quintuple-play OFDM services is demonstrated exceeding 60.8 km reach in standard single mode fiber. PMID:24663968

  14. Radio Resource Allocation on Complex 4G Wireless Cellular Networks

    NASA Astrophysics Data System (ADS)

    Psannis, Kostas E.

    2015-09-01

    In this article we consider the heuristic algorithm which improves step by step wireless data delivery over LTE cellular networks by using the total transmit power with the constraint on users’ data rates, and the total throughput with the constraints on the total transmit power as well as users’ data rates, which are jointly integrated into a hybrid-layer design framework to perform radio resource allocation for multiple users, and to effectively decide the optimal system parameter such as modulation and coding scheme (MCS) in order to adapt to the varying channel quality. We propose new heuristic algorithm which balances the accessible data rate, the initial data rates of each user allocated by LTE scheduler, the priority indicator which signals delay- throughput- packet loss awareness of the user, and the buffer fullness by achieving maximization of radio resource allocation for multiple users. It is noted that the overall performance is improved with the increase in the number of users, due to multiuser diversity. Experimental results illustrate and validate the accuracy of the proposed methodology.

  15. Does habitat heterogeneity in a multi-use landscape influence survival rates and density of a native mesocarnivore?

    PubMed

    Gese, Eric M; Thompson, Craig M

    2014-01-01

    The relationships between predators, prey, and habitat have long been of interest to applied and basic ecologists. As a native Great Plains mesocarnivore of North America, swift foxes (Vulpes velox) depended on the historic disturbance regime to maintain open grassland habitat. With a decline in native grasslands and subsequent impacts to prairie specialists, notably the swift fox, understanding the influence of habitat on native predators is paramount to future management efforts. From 2001 to 2004, we investigated the influence of vegetation structure on swift fox population ecology (survival and density) on and around the Piñon Canyon Maneuver Site, southeastern Colorado, USA. We monitored 109 foxes on 6 study sites exposed to 3 different disturbance regimes (military training, grazing, unused). On each site we evaluated vegetation structure based on shrub density, basal coverage, vegetation height, and litter. Across all sites, annual fox survival rates ranged from 0.50 to 0.92 for adults and 0.27 to 0.78 for juveniles. Among sites, population estimates ranged from 1 to 7 foxes per 10 km transect. Fox density or survival was not related to the relative abundance of prey. A robust model estimating fox population size and incorporating both shrub density and percent basal cover as explanatory variables far outperformed all other models. Our results supported the idea that, in our region, swift foxes were shortgrass prairie specialists and also indicated a relationship between habitat quality and landscape heterogeneity. We suggest the regulation of swift fox populations may be based on habitat quality through landscape-mediated survival, and managers may effectively use disturbance regimes to create or maintain habitat for this native mesocarnivore. PMID:24963713

  16. Distributed control of circuits in multiuser communication networks with circuit precedence and path suitability criteria using failsafe routing concepts

    NASA Astrophysics Data System (ADS)

    Ferrante, M. C.

    1984-12-01

    A distributed aperiodic failsafe algorithm is developed for application in a dedicated circuit allocation and restoral environment using circuit precedence features. The algorithm uses update control messages, initiated by changes in network topology or in user-defined truck weighting parameter, to determine shortest path routes. The number for the connected are compared with an equiprobable multinomial distribution and found to deviate only slightly from the hypothesized standard. Performance is slightly worse for a 16-node network than for an 8-node network. Single truck failures and subsequent circuit restoral indicate that high priority circuits will find new end-to-end paths but that low priority circuits stand little chance of restoral. Finally, attempts to include path suitability constraints verify that problem prone routes may be avoided if slightly larger average hop counts per circuit and fewer total circuit connections are tolerable.

  17. MissMarble, a multi-user interdisciplinary data base of marble for archaeometric, art historian and restoration use

    NASA Astrophysics Data System (ADS)

    Zöldföldi, J.; Székely, B.; Hegedüs, P.

    2009-04-01

    During a research project a lot of data are compiled by literature research, field studies, surveys, measurements. After the termination of the project these data remain in general unpublished, and are stored in the respective research institutions analogously or digitally. There exist the countless data which are stored on different media often decentralised in databases of different formats. All these data would be ready in principle for any scientific purposes on request; however, only the author has the information about the storage system of the data. This makes it difficult to verify the conclusions of the publications in the light of the gathered data; and this makes it almost impossible to prepare the data for later use in answering research-related questions. Sometimes unnecessarily repeated work is done; consequently the resources of the respective research equipment are needlessly used. To avoid duplicated research, the researchers are expected to publish the data together with the scientific contributions to provide public access to the original information. Nevertheless, it is often difficult to fulfil this demand. The standards for raw data publication are quite different from the requirements for research publications. The storage must be organised in such a way that it is conceivable for the researchers worldwide. Furthermore the data must be filed in reliable data centres where they are maintained and are put into archives for long time and remain available. The co-ordinated and clear availability of the research data serves all scientists - interdisciplinary and internationally. Via the availability of the raw data the original research results gain also importance and become valuable. Restorers, researchers working in various fields of humanities, museologists and specialists managing collections, are basically interested in the construction of data retrieval system of primary data. Thus, the storage, access and safety of scientific data can be assured via co-ordinated activity of the data producers. The aim of the MissMarble project was to develop an interdisciplinary data base management system for analytical results of marble occurrences (geological samples) and marble artefacts (archaeological and architectural objects). The system is characterised by user friendly interfaces for data entry, storage, continuous dissemination, and exchange. Furthermore the system provides practical hints to understand the techniques applied on various samples and relate them to other literature data. The goal of the developed system is to provide help for data comparison, provenance analyses and to reveal missing analytical results. The various user groups have different access rights. Beside of the Editors, Contributors are a special user group who are allowed to enter their own analytical results. Conceptually we intend to manage the results of analyses of both type of material (archaeological and geological samples) together to handle the data in the same manner. It enhances the overlaps and the gaps in the analytical results defining the further analyses to be done. The data entries are organized in the following scheme: sample identification; methods applied on the sample; colour and fabric; mineralogical composition; textural properties; chemical and isotope geochemical composition; engineering physical properties. Dependencies on the sample type: (in case of geological sample) geological classification (age, facies); (in case of archaeological samples) archaeological description of the objects; probable provenance (if determined); conservational and restoration experience. The system is designed so that further amendments and extensions are possible without data loss. It is updated and tailored according to the experience gathered during its use. To this end a pinboard is used for user feedback. The system functionalities, data structure and data content are regularly revised according to the requirements of the users and data providers. However, the amendments should be done so that the changes do not hamper the comparisons with the previous data and applied methods.

  18. Investigating Student Attitudes toward a Synchronous, Online Graduate Course in a Multi-User Virtual Learning Environment

    ERIC Educational Resources Information Center

    Annetta, Leonard; Murray, Marshall; Gull Laird, Shelby; Bohr, Stephanie; Park, John

    2008-01-01

    This article describes a graduate distance education course at North Carolina State University, which combined science content and pedagogy with video game design. The course was conducted entirely in a synchronous, online, Virtual Learning Environment (VLE) through the ActiveWorlds[TM] platform. Inservice teachers enrolled as graduate students in…

  19. Tele-Presence Microscopy: An interactive multi-user environment for Collaborative research using high speed networks and the Internet

    SciTech Connect

    Zaluzec, N.J.

    1996-03-01

    Tele-Presence Microscopy (TPM) is an advanced concept in the integration of computers and high speed networks with scientific instruments for operation, control, communication, and research, which makes use of ANL`s Advanced Analytical Electron Microscope and Analytical Scanning Electron Microscope as development/test bed sites. Implementation of a TPM facility allows a user from a remote location to either observe and/or control state-of-the-art instrumentation in a real time interactive mode. Using TPM, a user will be able to {ital actively} participate in scientific investigations at unique resources such as user facilities without being physically present at those locations. Manufacturers would be able to configure demonstration equipment and to remotely service/diagnose the system. Students would be able to initiate tele- presence operation of instruments which may not be available at their host institution; they would also be able to consult an advisor or nonlocal expert on-line. The generic TPM/LabSpace system is composed of both software and hardware which operate in a client/server relationship.

  20. The AstroVR Collaboratory, an On-line Multi-User Environment for Research in Astrophysics

    NASA Astrophysics Data System (ADS)

    van Buren, D.; Curtis, P.; Nichols, D. A.; Brundage, M.

    We describe our experiment with an on-line collaborative environment where users share the execution of programs and communicate via audio, video, and typed text. Collaborative environments represent the next step in computer-mediated conferencing, combining powerful compute engines, data persistence, shared applications, and teleconferencing tools. As proof of concept, we have implemented a shared image analysis tool, allowing geographically distinct users to analyze FITS images together. We anticipate that \\htmllink{AstroVR}{http://astrovr.ipac.caltech.edu:8888} and similar systems will become an important part of collaborative work in the next decade, including with applications in remote observing, spacecraft operations, on-line meetings, as well as and day-to-day research activities. The technology is generic and promises to find uses in business, medicine, government, and education.

  1. Multi-use applications of dual-band infrared (DBIR) thermal imaging for detecting obscured structural defects

    SciTech Connect

    Del Grande, N.K.; Durbin, P.F.

    1994-05-01

    Precise dual-band infrared (DBIR) thermal imaging provides a useful diagnostic tool for wide-area detection of defects from corrosion damage in metal airframes, heat damage in composite structures and structural damage in concrete bridge decks. We use DBIR image ratios to enhance surface temperature contrast, remove surface emissivity noise and increase signal-to-clutter ratios. We clarify interpretation of hidden defect sites by distinguishing temperature differences at defect sites from emissivity differences at clutter sites. This reduces the probability of false calls associated with misinterpreted image data. For airframe inspections, we map flash-heated defects in metal structures. The surface temperature rise above ambient at corrosion-thinned sites correlates with the percentage of material loss from corrosion thinning. For flash-heated composite structures, we measure the temperature-time history which relates to the depth and extent of heat damage. In preparation for bridge deck inspections, we map the natural day and night temperature variations at known concrete slab delamination sites which heat and coot at different rates than their surroundings. The above-ambient daytime and below-ambient nightime delamination site temperature differences correlate with the volume of replaced concrete at the delamination sites.

  2. Exploring the Use of Three-Dimensional Multi-User Virtual Environments for Online Problem-Based Learning

    ERIC Educational Resources Information Center

    Omale, Nicholas M.

    2010-01-01

    This exploratory case study examines how three media attributes in 3-D MUVEs--avatars, 3-D spaces and bubble dialogue boxes--affect interaction in an online problem-based learning (PBL) activity. The study participants were eleven undergraduate students enrolled in a 200-level, three-credit-hour technology integration course at a Midwestern…

  3. Installing and maintaining CDAT (Climate Data Analysis Tools) in multi-user and multi-platform environments

    NASA Astrophysics Data System (ADS)

    Peterschmitt, Jean-Yves

    2010-05-01

    CDAT is an extensible software environment for the climate scientist, based on the widely used python scripting language. Thanks to all the bundled python modules, CDAT can be used for a wide range of applications, from the powerful replacement of traditional shell scripts for automated data-processing to the interactive graphical analysis of scientific data (with an emphasis on climate data). CDAT is traditionally used as a single-user desktop tool (each user is responsible for his own version of CDAT). This poster will show how CDAT can be centrally installed, tested and maintained so that multiple users can easily and seamlessly use it in their laboratory and remote computing centers. We use the combination of standard initialization scripts (for the CDAT-manager and the end users) and of standard installation steps to deploy CDAT consistently on all the managed platforms (with the possible concurrent installation of different versions on the same platform). Reference: http://www2-pcmdi.llnl.gov/cdat

  4. Data Management and Archiving in a Large Microscopy-and-Imaging, Multi-User Facility: Problems and Solutions

    PubMed Central

    WALLACE, CALLEN T.; ST. CROIX, CLAUDETTE M.; WATKINS, SIMON C.

    2016-01-01

    SUMMARY Advancements in microscopy and imaging have pushed the boundaries of what was once thought possible in many fields of research. New techniques, coupled with the application of new technologies, allow researchers to answer increasingly complex questions by probing deeper and with greater accuracy. While, these new techniques provide far greater specificity and increased sensitivity in regards to both resolution and frequency, the amount of data generated is swelling to a point where conventional data-management systems struggle to keep pace; this is especially true for large microscopy-and-imaging shared-user facilities. Sub-optimal data management can severely hinder the ability of a researcher to determine experimental results accurately or efficiently, and will inevitably limit the functionality of the research facility itself. This review discusses the source of the problem: how data are produced by systems available today, and the information’s specificity and relative importance; techniques for management of these data to maximize functionality of the facility; and practices that can be detrimental in the research core environment. PMID:26284826

  5. Performance improvement of OFDM-FSO multi-user communication system with combined transmit frequency diversity and receive space diversity

    NASA Astrophysics Data System (ADS)

    Kumar, Pravindra; Srivastava, Anand

    2016-05-01

    Orthogonal frequency division multiplexed (OFDM) based free space optical (FSO) communication link gives improved performance because of narrow-band interference, improved robustness against fading and high bandwidth efficiency. It is further improved using transmit frequency diversity and space diversity at the receiver. In this paper, we propose to use OFDM architecture combined with spreading code in electrical domain, referred as code division multiplexed-orthogonal frequency division multiplexing (CDM-OFDM) which provides frequency diversity at the transmitter and using more than one receiver to get receive diversity. Analytical model of CDM-OFDM-FSO communication system with photo-detector space diversity using maximal ratio combining (MRC) is analyzed in the presence of turbulent atmosphere, multi-user-interference (MUI) and timing jitter. The error performance is computed in terms of receiver sensitivity and bit-error-rate (BER). In the analysis, Gamma-Gamma distribution is considered for atmospheric turbulence. The performance of OFDM-FSO link and CDM-OFDM-FSO link is compared. It is seen that for multiple users, CDM-OFDM-FSO link with transmit and receive diversity gives improved performance as compared to OFDM-FSO link.

  6. Opuntia in México: Identifying Priority Areas for Conserving Biodiversity in a Multi-Use Landscape

    PubMed Central

    Illoldi-Rangel, Patricia; Ciarleglio, Michael; Sheinvar, Leia; Linaje, Miguel; Sánchez-Cordero, Victor; Sarkar, Sahotra

    2012-01-01

    Background México is one of the world's centers of species diversity (richness) for Opuntia cacti. Yet, in spite of their economic and ecological importance, Opuntia species remain poorly studied and protected in México. Many of the species are sparsely but widely distributed across the landscape and are subject to a variety of human uses, so devising implementable conservation plans for them presents formidable difficulties. Multi–criteria analysis can be used to design a spatially coherent conservation area network while permitting sustainable human usage. Methods and Findings Species distribution models were created for 60 Opuntia species using MaxEnt. Targets of representation within conservation area networks were assigned at 100% for the geographically rarest species and 10% for the most common ones. Three different conservation plans were developed to represent the species within these networks using total area, shape, and connectivity as relevant criteria. Multi–criteria analysis and a metaheuristic adaptive tabu search algorithm were used to search for optimal solutions. The plans were built on the existing protected areas of México and prioritized additional areas for management for the persistence of Opuntia species. All plans required around one–third of México's total area to be prioritized for attention for Opuntia conservation, underscoring the implausibility of Opuntia conservation through traditional land reservation. Tabu search turned out to be both computationally tractable and easily implementable for search problems of this kind. Conclusions Opuntia conservation in México require the management of large areas of land for multiple uses. The multi-criteria analyses identified priority areas and organized them in large contiguous blocks that can be effectively managed. A high level of connectivity was established among the prioritized areas resulting in the enhancement of possible modes of plant dispersal as well as only a small number of blocks that would be recommended for conservation management. PMID:22606279

  7. Factors influencing aquatic-to-terrestrial contaminant transport to terrestrial arthropod consumers in a multiuse river system.

    PubMed

    Alberts, Jeremy M; Sullivan, S Mažeika P

    2016-06-01

    Emerging aquatic insects are important vectors of contaminant transfer from aquatic to terrestrial food webs. However, the environmental factors that regulate contaminant body burdens in nearshore terrestrial consumers remain largely unexplored. We investigated the relative influences of riparian landscape composition (i.e., land use and nearshore vegetation structure) and contaminant flux via the emergent aquatic insect subsidy on selenium (Se) and mercury (Hg) body burdens of riparian ants (Formica subsericea) and spiders of the family Tetragnathidae along 11 river reaches spanning an urban-rural land-use gradient in Ohio, USA. Model-selection results indicated that fine-scale land cover (e.g., riparian zone width, shrub cover) in the riparian zone was positively associated with reach-wide body burdens of Se and Hg in both riparian F. subsericea and tetragnathid spiders (i.e., total magnitude of Hg and Se concentrations in ant and spider populations, respectively, for each reach). River distance downstream of Columbus, Ohio - where study reaches were impounded and flow through a large urban center - was also implicated as an important factor. Although stable-isotope analysis suggested that emergent aquatic insects were likely vectors of Se and Hg to tetragnathid spiders (but not to F. subsericea), emergent insect contaminant flux did not emerge as a significant predictor for either reach-wide body burdens of spider Hg or Se. Improved understanding of the pathways and influences that control aquatic-to-terrestrial contaminant transport will be critical for effective risk management and remediation. PMID:26874875

  8. Non-LTE Inversion of Spectropolarimetric and Spectroscopic Observations of a Small Active-region Filament Observed at the VTT

    NASA Astrophysics Data System (ADS)

    Schwartz, P.; Balthasar, H.; Kuckein, C.; Koza, J.; Gömöry, P.; Rybák, J.; Kučera, A.; Heinzel, P.

    2016-04-01

    An active region mini-filament was observed by VTT simultaneously in the HeI 10 830 Å triplet by the TIP 1 spectropolarimeter, in Hα by the TESOS Fabry-Pérot interferometer, and in Ca II 8542 Å by the VTT spectrograph. The spectropolarimetric data were inverted using the HAZEL code and Hα profiles were modelled solving a NLTE radiative transfer in a simple isobaric and isothermal 2D slab irradiated both from bottom and sides. It was found that the mini-filament is composed of horizontal fluxtubes, along which the cool plasma of T˜10 000 K can flow by very large - even supersonic - velocities.

  9. Configuration interaction effect on open M shell Fe and Ni LTE spectral opacities, Rosseland and Planck means

    NASA Astrophysics Data System (ADS)

    Gilles, D.; Busquet, M.; Gilleron, F.; Klapisch, M.; Pain, J.-C.

    2016-05-01

    We have recently shown that iron and nickel open M-shell opacity spectra, up to Δn = 2 are very sensitive to Configuration Interaction (CI) treatments at temperature around 15 eV and for various densities. To do so we had compared extensive CI calculations obtained with two opacity codes HULLAC-v9 and SCO-RCG. In this work we extend these comparisons to a first evaluation of CI effects on Rosseland and Planck means.

  10. Near-LTE linear response calculations with a collisional-radiative model for He-like Al ions

    SciTech Connect

    More, R.M.; Kato, T.

    1998-01-06

    We investigate the non-equilibrium atomic kinetics using a collisional-radiative (CR) model modified to include line absorption. Steady-state emission is calculated for He-like aluminum ions immersed in a specified radiation field having fixed deviations from a Planck spectrum. The net emission is interpreted in terms of NLTE population changes. The calculation provides an NLTE response matrix, and in agreement with a general relation of non-equilibrium thermodynamics, the response matrix is symmetric. We compute the response matrix for 1% and 50% changes in the photon temperature and find linear response over a surprisingly large range.

  11. Near-LTE linear response calculations with a collisional-radiative model for He-like Al ions. Revision 1

    SciTech Connect

    More, R.; Kato, T.

    1998-04-06

    We investigate non-equilibrium atomic kinetics using a collisional- radiative model modified to include line absorption. Steady-state emission is calculated for He-like aluminum immersed in a specified radiation field having fixed deviations from a Planck spectrum. The calculated net emission is presented as a NLTE response matrix. In agreement with a rigorous general rule of non-equilibrium thermodynamics, the linear response is symmetric. We compute the response matrix for 1% and {+-} 50% changes in the photon temperature and find linear response over a surprisingly large range.

  12. The solution of radiative transfer problems in molecular bands without the LTE assumption by accelerated lambda iteration methods

    NASA Technical Reports Server (NTRS)

    Kutepov, A. A.; Kunze, D.; Hummer, D. G.; Rybicki, G. B.

    1991-01-01

    An iterative method based on the use of approximate transfer operators, which was designed initially to solve multilevel NLTE line formation problems in stellar atmospheres, is adapted and applied to the solution of the NLTE molecular band radiative transfer in planetary atmospheres. The matrices to be constructed and inverted are much smaller than those used in the traditional Curtis matrix technique, which makes possible the treatment of more realistic problems using relatively small computers. This technique converges much more rapidly than straightforward iteration between the transfer equation and the equations of statistical equilibrium. A test application of this new technique to the solution of NLTE radiative transfer problems for optically thick and thin bands (the 4.3 micron CO2 band in the Venusian atmosphere and the 4.7 and 2.3 micron CO bands in the earth's atmosphere) is described.

  13. Non-equilibrium ionized blast wave

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    1974-01-01

    The structure of a cylindrical blast wave with ionization at non-LTE conditions was calculated using equations previously developed by Wu and Fu (1970). The degree of ionization was predicted by a modified Saha equation. Temperature profiles show that the temperature at non-LTE conditions is lower than at LTE near the shock front. This corresponds to a higher degree of ionization for the non-LTE limit, which indicates that the neutral gas absorption is much more efficient at non-LTE than at the LTE limit. The decaying velocity under non-LTE is approximately 15% less than under LTE.

  14. See the Sea: multi-user information system for investigating processes and phenomena in coastal zones via satellite remotely sensed data, particularly hyperspectral data

    NASA Astrophysics Data System (ADS)

    Mityagina, Marina I.; Lavrova, Olga Yu.; Uvarov, Ivan A.

    2014-10-01

    The functionality, the goals and the current state of the distributed information system "See the Sea" (STS) are presented and discussed. This system is designed for investigating various processes and phenomena in the ocean and marine atmosphere using different types of satellite remotely sensed data. The STS system provides researchers with the possibilities to deal with the satellite remote sensing data as well as with the result of its analysis. The key feature of STS is the ability to work simultaneously with satellite information of different types. STS provides tools for joint analysis of different types of satellite data, as well as data of ground meteorological stations, cartographic data etc. This paper gives an overview of the system and data processing use cases. Some example cases are described including processing and joint analysis of various satellite data. The data from different sensors (obtained by Envisat ASAR, Landsat-8 OLI, Landsat-7 ETM+, Landsat-5 TM, Terra/Aqua MODIS as well as Hyperion and HICO hyperspectral data) was analyzed jointly for differentiation between different types of coastal waters, and for reconstruction of suspended matter distribution in the test areas of the Azov and Black Seas.

  15. Exploring Ecosystems from the Inside: How Immersive Multi-user Virtual Environments Can Support Development of Epistemologically Grounded Modeling Practices in Ecosystem Science Instruction

    NASA Astrophysics Data System (ADS)

    Kamarainen, Amy M.; Metcalf, Shari; Grotzer, Tina; Dede, Chris

    2015-04-01

    Recent reform efforts and the next generation science standards emphasize the importance of incorporating authentic scientific practices into science instruction. Modeling can be a particularly challenging practice to address because modeling occurs within a socially structured system of representation that is specific to a domain. Further, in the process of modeling, experts interact deeply with domain-specific content knowledge and integrate modeling with other scientific practices in service of a larger investigation. It can be difficult to create learning experiences enabling students to engage in modeling practices that both honor the position of the novice along a spectrum toward more expert understanding and align well with the practices and reasoning used by experts in the domain. In this paper, we outline the challenges in teaching modeling practices specific to the domain of ecosystem science, and we present a description of a curriculum built around an immersive virtual environment that offers unique affordances for supporting student engagement in modeling practices. Illustrative examples derived from pilot studies suggest that the tools and context provided within the immersive virtual environment helped support student engagement in modeling practices that are epistemologically grounded in the field of ecosystem science.

  16. A Multi-User Game-Theoretical Multipath Routing Protocol to Send Video-Warning Messages over Mobile Ad Hoc Networks

    PubMed Central

    Mezher, Ahmad Mohamad; Igartua, Mónica Aguilar; de la Cruz Llopis, Luis J.; Segarra, Esteve Pallarès; Tripp-Barba, Carolina; Urquiza-Aguiar, Luis; Forné, Jordi; Gargallo, Emilio Sanvicente

    2015-01-01

    The prevention of accidents is one of the most important goals of ad hoc networks in smart cities. When an accident happens, dynamic sensors (e.g., citizens with smart phones or tablets, smart vehicles and buses, etc.) could shoot a video clip of the accident and send it through the ad hoc network. With a video message, the level of seriousness of the accident could be much better evaluated by the authorities (e.g., health care units, police and ambulance drivers) rather than with just a simple text message. Besides, other citizens would be rapidly aware of the incident. In this way, smart dynamic sensors could participate in reporting a situation in the city using the ad hoc network so it would be possible to have a quick reaction warning citizens and emergency units. The deployment of an efficient routing protocol to manage video-warning messages in mobile Ad hoc Networks (MANETs) has important benefits by allowing a fast warning of the incident, which potentially can save lives. To contribute with this goal, we propose a multipath routing protocol to provide video-warning messages in MANETs using a novel game-theoretical approach. As a base for our work, we start from our previous work, where a 2-players game-theoretical routing protocol was proposed to provide video-streaming services over MANETs. In this article, we further generalize the analysis made for a general number of N players in the MANET. Simulations have been carried out to show the benefits of our proposal, taking into account the mobility of the nodes and the presence of interfering traffic.Finally, we also have tested our approach in a vehicular ad hoc network as an incipient start point to develop a novel proposal specifically designed for VANETs. PMID:25897496

  17. Exploring Ecosystems from the Inside: How Immersive Multi-User Virtual Environments Can Support Development of Epistemologically Grounded Modeling Practices in Ecosystem Science Instruction

    ERIC Educational Resources Information Center

    Kamarainen, Amy M.; Metcalf, Shari; Grotzer, Tina; Dede, Chris

    2015-01-01

    Recent reform efforts and the next generation science standards emphasize the importance of incorporating authentic scientific practices into science instruction. Modeling can be a particularly challenging practice to address because modeling occurs within a socially structured system of representation that is specific to a domain. Further, in the…

  18. Characterization of a multi-user indoor positioning system based on low cost depth vision (Kinect) for monitoring human activity in a smart home.

    PubMed

    Sevrin, Loïc; Noury, Norbert; Abouchi, Nacer; Jumel, Fabrice; Massot, Bertrand; Saraydaryan, Jacques

    2015-01-01

    An increasing number of systems use indoor positioning for many scenarios such as asset tracking, health care, games, manufacturing, logistics, shopping, and security. Many technologies are available and the use of depth cameras is becoming more and more attractive as this kind of device becomes affordable and easy to handle. This paper contributes to the effort of creating an indoor positioning system based on low cost depth cameras (Kinect). A method is proposed to optimize the calibration of the depth cameras, to describe the multi-camera data fusion and to specify a global positioning projection to maintain the compatibility with outdoor positioning systems. The monitoring of the people trajectories at home is intended for the early detection of a shift in daily activities which highlights disabilities and loss of autonomy. This system is meant to improve homecare health management at home for a better end of life at a sustainable cost for the community. PMID:26737415

  19. Analysis of high-frequency water quality data collected during a cyanoHAB event on an inland, multi-use reservoir

    EPA Science Inventory

    We describe here an effort to use high frequency data collected from online, continuous monitors coupled with field collected data to describe the temporal relationship between suspected HAB drivers and observed cyanoHABs and cyanotoxin production to provide insight on the necess...

  20. A Comparison of the Effects of Classroom and Multi-User Virtual Environments on the Perceived Speaking Anxiety of Adult Post-Secondary English Language Learners

    ERIC Educational Resources Information Center

    Abal, Abdulaziz

    2013-01-01

    The population of English Language Learners (ELLs) globally has been increasing substantially every year. In the United States alone, adult ELLs are the fastest growing portion of learners in adult education programs (Yang, 2005). There is a significant need to improve the teaching of English to ELLs in the United States and other English-speaking…

  1. A Multi-User Game-Theoretical Multipath Routing Protocol to Send Video-Warning Messages over Mobile Ad Hoc Networks.

    PubMed

    Mezher, Ahmad Mohamad; Igartua, Mónica Aguilar; de la Cruz Llopis, Luis J; Pallarès Segarra, Esteve; Tripp-Barba, Carolina; Urquiza-Aguiar, Luis; Forné, Jordi; Sanvicente Gargallo, Emilio

    2015-01-01

    The prevention of accidents is one of the most important goals of ad hoc networks in smart cities. When an accident happens, dynamic sensors (e.g., citizens with smart phones or tablets, smart vehicles and buses, etc.) could shoot a video clip of the accident and send it through the ad hoc network. With a video message, the level of seriousness of the accident could be much better evaluated by the authorities (e.g., health care units, police and ambulance drivers) rather than with just a simple text message. Besides, other citizens would be rapidly aware of the incident. In this way, smart dynamic sensors could participate in reporting a situation in the city using the ad hoc network so it would be possible to have a quick reaction warning citizens and emergency units. The deployment of an efficient routing protocol to manage video-warning messages in mobile Ad hoc Networks (MANETs) has important benefits by allowing a fast warning of the incident, which potentially can save lives. To contribute with this goal, we propose a multipath routing protocol to provide video-warning messages in MANETs using a novel game-theoretical approach. As a base for our work, we start from our previous work, where a 2-players game-theoretical routing protocol was proposed to provide video-streaming services over MANETs. In this article, we further generalize the analysis made for a general number of N players in the MANET. Simulations have been carried out to show the benefits of our proposal, taking into account the mobility of the nodes and the presence of interfering traffic. Finally, we also have tested our approach in a vehicular ad hoc network as an incipient start point to develop a novel proposal specifically designed for VANETs. PMID:25897496

  2. Combined peak-to-average power ratio reduction and physical layer security enhancement in optical orthogonal frequency division multiplexing visible-light communication systems

    NASA Astrophysics Data System (ADS)

    Wang, Zhongpeng; Chen, Shoufa

    2016-07-01

    A physical encryption scheme for discrete Hartley transform (DHT) precoded orthogonal frequency division multiplexing (OFDM) visible-light communication (VLC) systems using frequency domain chaos scrambling is proposed. In the scheme, the chaos scrambling, which is generated by a modified logistic mapping, is utilized to enhance the physical layer of security, and the DHT precoding is employed to reduce of OFDM signal for OFDM-based VLC. The influence of chaos scrambling on peak-to-average power ratio (PAPR) and bit error rate (BER) of systems is studied. The experimental simulation results prove the efficiency of the proposed encryption method for DHT-precoded, OFDM-based VLC systems. Furthermore, the influence of the proposed encryption to the PAPR and BER of systems is evaluated. The experimental results show that the proposed security scheme can protect the DHT-precoded, OFDM-based VLC from eavesdroppers, while keeping the good BER performance of DHT-precoded systems. The BER performance of the encrypted and DHT-precoded system is almost the same as that of the conventional DHT-precoded system without encryption.

  3. Simultaneous retrieval of T(p) and CO2 VMR from two-channel non-LTE limb radiances and application to daytime SABER/TIMED measurements

    NASA Astrophysics Data System (ADS)

    Rezac, L.; Kutepov, A.; Russell, J. M.; Feofilov, A. G.; Yue, J.; Goldberg, R. A.

    2015-08-01

    The kinetic temperature, Tk, and carbon dioxide, CO2 density, are key parameters that characterize the energetics and dynamics of the mesosphere and lower thermosphere (MLT) region. The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on-board the Thermosphere-Ionosphere-Mesosphere-Energetics and Dynamics (TIMED) satellite has been providing global, simultaneous measurements of limb radiance in 10 spectral channels continuously since late January 2002. In this paper we (1) present a methodology for a self-consistent simultaneous retrieval of temperature/pressure, Tk(p), and CO2 volume mixing ratio (VMR) from the broadband infrared limb measurements in the 15 and 4.3 μm channels, and (2) qualitatively describe the first results on the CO2 VMR and Tk obtained from application of this technique to the SABER 15 and 4.3 μm channels, including issues, which demand additional constraints to be applied. The self-consistent two-channel retrieval architecture updates parameters at all altitudes simultaneously, and it is built upon iterative switching between two retrieval modules, one for CO2 and one for Tk. A detailed study of sensitivity, stability and convergence was carried out to validate the algorithm. The Tk/CO2 VMR distribution can be reliably retrieved without biases connected with this non-linear inverse problem starting with an initial guess as far as ±20% of CO2 VMR and ±15 K from the solution (as global shift, or somewhat larger if only local deviations are considered). In polar summer toward high latitudes the retrieved CO2 VMR profile shows a local peak around 90 km. We discuss details of this feature and show that: (a) it is not an algorithm artifact or instability, (b) additional a priori constraints are needed in order to obtain a physical profile and to remove this peak, and (c) several possibilities are explored as to uncover the real cause of this feature, but no firm conclusion can be reached at this time. This algorithm has been applied to all available daytime SABER measurements since 2002, and the first results of the mean CO2 VMR profiles and their distribution is discussed. In particular, the CO2 VMR profiles depart from a well mixed value at altitudes of 65-70 km during equinoxes at high and mid-latitudes, but in the summer hemisphere solstice period the SABER data is more consistent with a well mixed VMR conditions extend up to 87-90 km especially toward high latitudes.

  4. EX Lupi FROM QUIESCENCE TO OUTBURST: EXPLORING THE LTE APPROACH IN MODELING BLENDED H{sub 2}O AND OH MID-INFRARED EMISSION

    SciTech Connect

    Banzatti, A.; Meyer, M. R.; Bruderer, S.; Geers, V.; Pascucci, I.; Lahuis, F.; Juhasz, A.; Henning, T.; Abraham, P.

    2012-01-20

    We present a comparison of archival Spitzer spectra of the strongly variable T Tauri EX Lupi, observed before and during its 2008 outburst. We analyze the mid-infrared emission from gas-phase molecules thought to originate in a circumstellar disk. In quiescence the emission shows a forest of H{sub 2}O lines, highly excited OH lines, and the Q branches of the organics C{sub 2}H{sub 2}, HCN, and CO{sub 2}, similar to the emission observed toward several T Tauri systems. The outburst emission shows instead remarkable changes: H{sub 2}O and OH line fluxes increase, new OH, H{sub 2}, and H I transitions are detected, and organics are no longer seen. We adopt a simple model of a single-temperature slab of gas in local thermal equilibrium, a common approach for molecular analyses of Spitzer spectra, and derive the excitation temperature, column density, and emitting area of H{sub 2}O and OH. We show how model results strongly depend on the selection of emission lines fitted and how this is likely to be attributed to a combination of non-thermal excitation and multiple emission components. Using H{sub 2}O lines that can be approximated as thermalized to a single temperature, our results are consistent with a column density decrease in outburst while the emitting area of warm gas increases. A rotation diagram analysis suggests that the OH emission can be explained with two temperature components, which remarkably increase in column density in outburst. The relative change of H{sub 2}O and OH emission suggests a key role for UV radiation in the disk surface chemistry.

  5. Three-dimensional non-LTE radiative transfer effects in Fe i lines. III. Line formation in magneto-hydrodynamic atmospheres

    NASA Astrophysics Data System (ADS)

    Holzreuter, R.; Solanki, S. K.

    2015-10-01

    Non-local thermodynamic equilibrium (NLTE) effects in diagnostically important solar Fe i lines are important because of the strong sensitivity of Fe i to ionizing UV radiation, which may lead to a considerable underpopulation of the Fe i levels in the solar atmosphere and, therefore, to a sizeable weakening of Fe i lines. These NLTE effects may be intensified or weakened by horizontal radiative transfer (RT) in a three-dimensionally (3D) structured atmosphere. We analyze the influence of horizontal RT on commonly used Fe i lines in a snapshot of a 3D radiation magneto-hydrodynamic (MHD) simulation of a plage region. NLTE and horizontal RT effects occur with considerable strength (up to 50% in line depth or equivalent width) in the analyzed snapshot. Because they may have either sign, and both signs occur with approximately the same frequency and strength, the net effects are small when considering spatially averaged quantities. The situation in the plage atmosphere turns out to be rather complex. Horizontal transfer leads to line weakening relative to 1D NLTE transfer near the boundaries of kG magnetic elements. Around the centers of these elements, however, we find line strengthening, which is often significant. This behavior contrasts with what is expected from previous 3D RT computations in idealized flux-tube models, which only display line weakening. The origin of this unexpected behavior lies in the fact that magnetic elements are surrounded by dense and relatively cool downflowing gas, which forms the walls of the magnetic elements. The continuum in these dense walls is often formed in colder gas than in the central part of the magnetic elements. Consequently, the central parts of the magnetic element experience a subaverage UV-irradiation leading to the observed 3D NLTE line strengthening.

  6. FORMAC integration program: A special applications package used in developing techniques of orbital decay and long term ephemeris prediction for satellites in earth orbit

    NASA Technical Reports Server (NTRS)

    Rowe, C. K.

    1971-01-01

    The symbolic manipulation capabilities of the FORMAC (Formula Manipulation Compiler) language are employed to expand and analytically evaluate integrals. The program integration is effected by expanding the integral(s) into a series of subintegrals and then substituting a pre-derived and pre-coded solution for that particular subintegral. Derivation of the integral solutions necessary for precoding is included, as is a discussion of the FORMAC system limitations encountered in the programming effort.

  7. Optimized Configurable Architectures for Scalable Soft-Input Soft-Output MIMO Detectors With 256-QAM

    NASA Astrophysics Data System (ADS)

    Mansour, Mohammad M.; Jalloul, Louay M. A.

    2015-09-01

    This paper presents an optimized low-complexity and high-throughput multiple-input multiple-output (MIMO) signal detector core for detecting spatially-multiplexed data streams. The core architecture supports various layer configurations up to 4, while achieving near-optimal performance, as well as configurable modulation constellations up to 256-QAM on each layer. The core is capable of operating as a soft-input soft-output log-likelihood ratio (LLR) MIMO detector which can be used in the context of iterative detection and decoding. High area-efficiency is achieved via algorithmic and architectural optimizations performed at two levels. First, distance computations and slicing operations for an optimal 2-layer maximum a posteriori (MAP) MIMO detector are optimized to eliminate the use of multipliers and reduce the overhead of slicing in the presence of soft-input LLRs. We show that distances can be easily computed using elementary addition operations, while optimal slicing is done via efficient comparisons with soft decision boundaries, resulting in a simple feed-forward pipelined architecture. Second, to support more layers, an efficient channel decomposition scheme is presented that reduces the detection of multiple layers into multiple 2-layer detection subproblems, which map onto the 2-layer core with a slight modification using a distance accumulation stage and a post-LLR processing stage. Various architectures are accordingly developed to achieve a desired detection throughput and run-time reconfigurability by time-multiplexing of one or more component cores. The proposed core is applied as well to design an optimal multi-user MIMO detector for LTE. The core occupies an area of 1.58MGE and achieves a throughput of 733 Mbps for 256-QAM when synthesized in 90 nm CMOS.

  8. Modeling the physical structure of star-forming regions with LIME, a 3D radiative transfer code

    NASA Astrophysics Data System (ADS)

    Quénard, D.; Bottinelli, S.; Caux, E.

    2016-05-01

    The ability to predict line emission is crucial in order to make a comparison with observations. From LTE to full radiative transfer codes, the goal is always to derive the most accurately possible the physical properties of the source. Non-LTE calculations can be very time consuming but are needed in most of the cases since many studied regions are far from LTE.

  9. An Improved Optical Model for the Non-LTE Problem for the CO2 Molecule in the Atmosphere of Mars: Nighttime Populations of Vibrational States and the Rate of Radiative Cooling of the Atmosphere

    NASA Astrophysics Data System (ADS)

    Ogibalov, V. P.; Shved, G. M.

    2003-01-01

    The estimates of the population of excited vibrational states of the CO2 molecule and of the rate of radiative cooling of the atmosphere in the 15-μm CO2 band are given for the nighttime mesosphere and thermosphere of Mars. For the first time, these estimates are made (1) with allowance for the overlap of lines in the 15-μm band; (2) for a wide set of vibrational states of seven isotopes of the CO2 molecule, which was used earlier in the solution of a similar terrestrial problem; and (3) using the rate constant for quenching of the CO2(0110) state in collisions with oxygen atoms, which has been recently measured for low temperatures by Khvorostovskaya et al. (2002). The main results are as follows. 1. The approximation of isolated lines provides a satisfactory accuracy of determining the radiative cooling rate and overestimates vibrational temperatures of the states of the ν2 mode by no more than 3 K for the 12C16O2 molecule and by no more than 2 K for low-abundant isotopes of the CO2 molecule. 2. A reasonably high accuracy of estimating the cooling rate can be achieved by taking into account only fundamental vibrational transitions in 12C16O2, 13C16O2, 16O12C18O, and 16O12C17O molecules and the hot transitions 2ν2 --> ν2 and 3ν2 --> 2ν2 in the 12C16O2 molecule. 3. The vertical profile of the total rate of radiative cooling displays two peaks. The maximum near a height of 130 km is very sensitive to temperature and to the ratio of the mixture for oxygen in the atmosphere.

  10. Photonic vector signal generation at W-band employing an optical frequency octupling scheme enabled by a single MZM

    NASA Astrophysics Data System (ADS)

    Li, Xinying; Yu, Jianjun; Zhang, Ziran; Xiao, Jiangnan; Chang, Gee-Kung

    2015-08-01

    We propose photonic vector signal generation at millimeter-wave (mm-wave) bands enabled by a single Mach-Zehnder modulator (MZM) and phase-precoding technique, which can realize photonic frequency multiplication of the precoded microwave vector signal used for the drive of the single MZM. We also experimentally demonstrate the generation of quadrature-phase-shift-keying (QPSK) modulated vector signal at W-band adopting photonic frequency octupling (×8) based on our proposed scheme. The MZM is driven by a 12-GHz QPSK modulated precoded vector signal. Up to 4-Gbaud QPSK-modulated electrical vector signal at 96 GHz is generated and then delivered over 3-m wireless transmission distance.

  11. Potholes on the Infobahn: Hazardous Conditions Ahead?

    ERIC Educational Resources Information Center

    Laughon, Sally; Hanson, William R.

    1996-01-01

    Alerts educators to potentially objectionable Internet materials. Electronic mail, newsgroups, file transfer protocol sites, Internet Relay Chat (IRC), Multiuser Dungeons (MUDs), and Multiuser Object Oriented (MOOs) are services whose user anonymity can embolden discussions regarding sex, prejudice, religious dogma, and gambling. Teachers may wish…

  12. Computer Center: CIBE Systems.

    ERIC Educational Resources Information Center

    Crovello, Theodore J.

    1982-01-01

    Differentiates between computer systems and Computers in Biological Education (CIBE) systems (computer system intended for use in biological education). Describes several CIBE stand alone systems: single-user microcomputer; single-user microcomputer/video-disc; multiuser microcomputers; multiuser maxicomputer; and local and long distance computer…

  13. Second Life in Higher Education: Assessing the Potential for and the Barriers to Deploying Virtual Worlds in Learning and Teaching

    ERIC Educational Resources Information Center

    Warburton, Steven

    2009-01-01

    "Second Life" (SL) is currently the most mature and popular multi-user virtual world platform being used in education. Through an in-depth examination of SL, this article explores its potential and the barriers that multi-user virtual environments present to educators wanting to use immersive 3-D spaces in their teaching. The context is set by…

  14. Relating Narrative, Inquiry, and Inscriptions: Supporting Consequential Play

    ERIC Educational Resources Information Center

    Barab, Sasha A.; Sadler, Troy D.; Heiselt, Conan; Hickey, Daniel; Zuiker, Steven

    2007-01-01

    In this paper we describe our research using a multi-user virtual environment, "Quest Atlantis," to embed fourth grade students in an aquatic habitat simulation. Specifically targeted towards engaging students in a rich inquiry investigation, we layered a socio-scientific narrative and an interactive rule set into a multi-user virtual environment…

  15. Educational MOO: Text-Based Virtual Reality for Learning in Community. ERIC Digest.

    ERIC Educational Resources Information Center

    Turbee, Lonnie

    MOO stands for "Multi-user domain, Object-Oriented." Early multi-user domains, or "MUDs," began as net-based dungeons-and-dragons type games, but MOOs have evolved from these origins to become some of cyberspace's most fascinating and engaging online communities. MOOs are social environments in a text-based virtual reality where people gather to…

  16. Pre-Service Teachers' Perspectives on Using Scenario-Based Virtual Worlds in Science Education

    ERIC Educational Resources Information Center

    Kennedy-Clark, Shannon

    2011-01-01

    This paper presents the findings of a study on the current knowledge and attitudes of pre-service teachers on the use of scenario-based multi-user virtual environments in science education. The 28 participants involved in the study were introduced to "Virtual Singapura," a multi-user virtual environment, and completed an open-ended questionnaire.…

  17. 78 Battered Children: A Retrospective Study.

    ERIC Educational Resources Information Center

    Skinner, Angela E.; Castle, Raymond L.

    The National Society for the Prevention of Cruelty to Children financed this study of the battered-child syndrome and provided case study data on a sample of 78 battered children under the age of 4 years, from low socioeconomic status families. Case study information was transferred to a precoded questionnaire. Tables of demographic and medical…

  18. The POK project; studies of information handling problems with a new kind of communication device

    NASA Astrophysics Data System (ADS)

    Dahlstedt, S.; Modeer, B.

    1984-12-01

    Equipment in which voice communication is replaced by the transmission of very brief precoded signals is described. Learning of vocabularies ranging from 6 to 30 abbreviated codes, and sending/receiving of complete orders of varying complexity were studied. The results show that it is possible for senders and receivers to manage a vocabulary of 30 coded expressions for transmission of intelligible combat orders.

  19. Out-of-band emission suppression techniques based on a generalized OFDM framework

    NASA Astrophysics Data System (ADS)

    You, Zihao; Fang, Juan; Lu, I.-Tai

    2014-12-01

    Orthogonal frequency division multiplexing (OFDM)-based cognitive radio (CR) systems suffer from the large out-of-band emission (OOBE) that may interfere with other users. Since most existing OFDM OOBE suppression schemes are derived on the base of an original OFDM system without any other scheme, we first propose a generalized OFDM framework that is capable of describing these schemes no matter whether any one or more of the schemes is applied. Then, according to the place where these schemes are implemented in our framework, they are classified into three groups, namely symbol mapping techniques, precoding techniques, and time-domain techniques. Finally, based on the proposed framework, we propose three new schemes by combining a precoding scheme named singular value decomposition (SVD) precoding with three other schemes from the three groups, namely spectral precoding, N-continuous symbol mapping, and filtering. Numerical results show the power spectral density (PSD), peak-to-average power ratio (PAPR), and bit error rate (BER) performances of the three proposed schemes. Since the individual schemes have complementary characteristics, the three proposed combined schemes are constructed to maintain the merits and avoid the drawbacks of the individual schemes involved. Thus, it is demonstrated that the proposed framework can be employed to develop other new combined OOBE suppression schemes tailoring to some specific practical needs.

  20. Analysis of C II resonance lines in some main sequence early-type stars

    NASA Technical Reports Server (NTRS)

    Cugier, H.; Hardorp, J.

    1988-01-01

    IUE data are used to investigate C II resonance lines at 1335 A in eight main-sequence stars of spectral types from A0 to B3, and both LTE and non-LTE line profiles have been computed. In stars with low rotational velocities (such as Vega, Pi Cet, and Tau Her), logarithmic carbon abundances log N(C/H) of -3.55 to -3.45 are obtained for the non-LTE case. The LTE analysis reveals lower carbon abundances by about 0.1 dex. Significant differences among the fast rotating stars are pointed out.

  1. Leukotriene E(4) in urine in patients with asthma and COPD--the effect of smoking habit.

    PubMed

    Gaki, E; Papatheodorou, G; Ischaki, E; Grammenou, V; Papa, I; Loukides, S

    2007-04-01

    Leukotriene E(4) (LTE(4)) is implicated in asthma pathophysiology and possibly in chronic obstructive pulmonary disease (COPD) as one of the causes of persistent bronchoconstriction and mucus hypersecretion. Cigarette smoking stimulates cysteinyl leukotrienes (CysLTs) production. We investigated whether LTE(4) is equally increased in asthma and COPD and whether smoking significantly affects LTE(4) levels. Secondary outcomes involved correlations with inflammatory and functional parameters. We studied 40 patients with COPD [20 smokers], 40 asthmatics [20 smokers] and 30 healthy subjects [15 smokers]. Spirometry (FEV(1)% pred., FEV(1)/FVC) was performed, urine was collected for measurement of LTE(4) and creatinine, induced sputum was collected for differential cell counts and serum for ECP. LTE(4)/creatinine levels (pg/mg) [mean (sd)] were increased in asthmatic patients compared to COPD and controls, [125.6(54.5) vs. 54.5(19) vs. 55.9(18.9)pg/mg, respectively, P<0.0001 for asthma]. Smoking significantly affects LTE(4) levels only in asthmatic patients [164 (48) vs. 87 (26.3), P<0.0001 for smokers]. The only significant correlation was between eosinophils in induced sputum and LTE(4)/creatinine levels in asthmatics. In conclusion, patients with asthma presented higher LTE(4) values compared to normals and patients with COPD. Smoking significantly affects LTE(4) values only in asthmatics indicating a different underlying CysLTs inflammatory process in this condition. PMID:16965907

  2. Validation and Application of the Constructivist Learning Environment Survey in English Language Teacher Education Classrooms in Iran

    ERIC Educational Resources Information Center

    Ebrahimi, Nabi. A.

    2015-01-01

    This article reports the validation and application of an English language teacher education (LTE) version of the Constructivist Learning Environment Survey (CLES). The instrument, called the CLES-LTE, was field tested with a sample of 622 Iranian English language student teachers in 28 classes. When principal components analysis led to the…

  3. 78 FR 72851 - Commission Seeks Comment on Licensing Models and Technical Requirements in the 3550-3650 MHz Band

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-04

    ... to LTE), but also on coexistence issues between disparate systems (e.g., LTE to Wi-Fi). Are different... Commission's Public Notice in GN Docket No. 12-354, FCC 13-144A1, Notice of Proposed Rulemaking, 78 FR 1188... Proceedings, 63 FR 24121 (1998). Electronic Filers: Comments may be filed electronically using the Internet...

  4. Predicting agricultural management influence on long-term soil organic carbon dynamics: implications for biofuel production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Long-term field experiments (LTE) are ideal for predicting the influence of agricultural management on soil organic carbon (SOC) dynamics and examining biofuel crop residue removal policy questions. Our objectives were (i) to simulate SOC dynamics in LTE soils under various climates, crop rotations,...

  5. Local thermodynamic equilibrium in rapidly heated high energy density plasmas

    SciTech Connect

    Aslanyan, V.; Tallents, G. J.

    2014-06-15

    Emission spectra and the dynamics of high energy density plasmas created by optical and Free Electron Lasers (FELs) depend on the populations of atomic levels. Calculations of plasma emission and ionization may be simplified by assuming Local Thermodynamic Equilibrium (LTE), where populations are given by the Saha-Boltzmann equation. LTE can be achieved at high densities when collisional processes are much more significant than radiative processes, but may not be valid if plasma conditions change rapidly. A collisional-radiative model has been used to calculate the times taken by carbon and iron plasmas to reach LTE at varying densities and heating rates. The effect of different energy deposition methods, as well as Ionization Potential Depression are explored. This work shows regimes in rapidly changing plasmas, such as those created by optical lasers and FELs, where the use of LTE is justified, because timescales for plasma changes are significantly longer than the times needed to achieve an LTE ionization balance.

  6. Local thermodynamic equilibrium in rapidly heated high energy density plasmas

    NASA Astrophysics Data System (ADS)

    Aslanyan, V.; Tallents, G. J.

    2014-06-01

    Emission spectra and the dynamics of high energy density plasmas created by optical and Free Electron Lasers (FELs) depend on the populations of atomic levels. Calculations of plasma emission and ionization may be simplified by assuming Local Thermodynamic Equilibrium (LTE), where populations are given by the Saha-Boltzmann equation. LTE can be achieved at high densities when collisional processes are much more significant than radiative processes, but may not be valid if plasma conditions change rapidly. A collisional-radiative model has been used to calculate the times taken by carbon and iron plasmas to reach LTE at varying densities and heating rates. The effect of different energy deposition methods, as well as Ionization Potential Depression are explored. This work shows regimes in rapidly changing plasmas, such as those created by optical lasers and FELs, where the use of LTE is justified, because timescales for plasma changes are significantly longer than the times needed to achieve an LTE ionization balance.

  7. Attitude control and stabilization technology discipline

    NASA Technical Reports Server (NTRS)

    Sunkel, John W.

    1990-01-01

    Viewgraphs on attitude control and stabilization technology discipline for the Space Station Freedom are presented. Topics covered include: attitude control technologies for multi-user accommodation; flexible dynamics and control; computational control techniques; and automatic proximity operations.

  8. An Introduction to Database Structure and Database Machines.

    ERIC Educational Resources Information Center

    Detweiler, Karen

    1984-01-01

    Enumerates principal management objectives of database management systems (data independence, quality, security, multiuser access, central control) and criteria for comparison (response time, size, flexibility, other features). Conventional database management systems, relational databases, and database machines used for backend processing are…

  9. 77 FR 31581 - U.S. Architecture Services Trade Mission to India; Chennai, Kolkata and Bangalore, India; October...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-29

    ... educational and hospitality projects launched by the private sector as well as multi-use township and... factors, such as diversity of company size, type, location, and demographics, may also be...

  10. MC-CDMA for optical wireless communications

    NASA Astrophysics Data System (ADS)

    Luan, Yingzi; Jiang, Guang; Li, Jiandong

    2005-11-01

    MC-CDMA is a spectrum-efficient modulation in RF systems. Here it is used in optical wireless communications. Performance is simulated by using multiuser detection. Spatial Diversity is also considered and analyzed.

  11. Vector 8QAM signal generation and transmission based on optical carrier suppression

    NASA Astrophysics Data System (ADS)

    Xiao, Jiangnan; Zhang, Zirang; Li, Xingying; Xu, Yuming; Chen, Long; Yu, Jianjun

    2015-11-01

    We experimentally demonstrate how to generate photonic eight quadrature amplitude modulation (M-QAM) vector signal by using only one Mach-Zehnder modulator (MZM). Because of the 'square-law' characteristic of the photodetector (PD), the amplitudes and the phase of the driving radio-frequency (RF) signal are changed after detection. The pre-coding for the amplitudes and the phase of the driving radio-frequency (RF) signal before they drive the MZM will take the advantages of restoring the driving precoding signal to regular signal after PD. The transmission performance with different date rates at 1, 2, and 3-Gbaud over single-mode fiber (SMF) transmission is experimentally demonstrated. The bit-error ratios (BERs) of the transmission system are less than the forward-error-correction (FEC) threshold of 3.8×10-3.

  12. 20. General view, outbuildings, from the southwest. From right to ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. General view, outbuildings, from the southwest. From right to left: the seed house, the former coach house (now multi-use space and the archives), and the former stable. Behind these buildings are a bank barn (now multi-use space) and a new office/restroom structure located on the site of a nineteenth-century frame farm building. - John Bartram House & Garden, Greenhouse, 54th Street & LIndbergh Boulevard, Philadelphia, Philadelphia County, PA

  13. ARA type protograph codes

    NASA Technical Reports Server (NTRS)

    Divsalar, Dariush (Inventor); Abbasfar, Aliazam (Inventor); Jones, Christopher R. (Inventor); Dolinar, Samuel J. (Inventor); Thorpe, Jeremy C. (Inventor); Andrews, Kenneth S. (Inventor); Yao, Kung (Inventor)

    2008-01-01

    An apparatus and method for encoding low-density parity check codes. Together with a repeater, an interleaver and an accumulator, the apparatus comprises a precoder, thus forming accumulate-repeat-accumulate (ARA codes). Protographs representing various types of ARA codes, including AR3A, AR4A and ARJA codes, are described. High performance is obtained when compared to the performance of current repeat-accumulate (RA) or irregular-repeat-accumulate (IRA) codes.

  14. Automated Engineering Design (AED); An approach to automated documentation

    NASA Technical Reports Server (NTRS)

    Mcclure, C. W.

    1970-01-01

    The automated engineering design (AED) is reviewed, consisting of a high level systems programming language, a series of modular precoded subroutines, and a set of powerful software machine tools that effectively automate the production and design of new languages. AED is used primarily for development of problem and user-oriented languages. Software production phases are diagramed, and factors which inhibit effective documentation are evaluated.

  15. Maximum likelihood decoding analysis of Accumulate-Repeat-Accumulate Codes

    NASA Technical Reports Server (NTRS)

    Abbasfar, Aliazam; Divsalar, Dariush; Yao, Kung

    2004-01-01

    Repeat-Accumulate (RA) codes are the simplest turbo-like codes that achieve good performance. However, they cannot compete with Turbo codes or low-density parity check codes (LDPC) as far as performance is concerned. The Accumulate Repeat Accumulate (ARA) codes, as a subclass of LDPC codes, are obtained by adding a pre-coder in front of RA codes with puncturing where an accumulator is chosen as a precoder. These codes not only are very simple, but also achieve excellent performance with iterative decoding. In this paper, the performance of these codes with (ML) decoding are analyzed and compared to random codes by very tight bounds. The weight distribution of some simple ARA codes is obtained, and through existing tightest bounds we have shown the ML SNR threshold of ARA codes approaches very closely to the performance of random codes. We have shown that the use of precoder improves the SNR threshold but interleaving gain remains unchanged with respect to RA code with puncturing.

  16. Accumulate repeat accumulate codes

    NASA Technical Reports Server (NTRS)

    Abbasfar, Aliazam; Divsalar, Dariush; Yao, Kung

    2004-01-01

    In this paper we propose an innovative channel coding scheme called 'Accumulate Repeat Accumulate codes' (ARA). This class of codes can be viewed as serial turbo-like codes, or as a subclass of Low Density Parity Check (LDPC) codes, thus belief propagation can be used for iterative decoding of ARA codes on a graph. The structure of encoder for this class can be viewed as precoded Repeat Accumulate (RA) code or as precoded Irregular Repeat Accumulate (IRA) code, where simply an accumulator is chosen as a precoder. Thus ARA codes have simple, and very fast encoder structure when they representing LDPC codes. Based on density evolution for LDPC codes through some examples for ARA codes, we show that for maximum variable node degree 5 a minimum bit SNR as low as 0.08 dB from channel capacity for rate 1/2 can be achieved as the block size goes to infinity. Thus based on fixed low maximum variable node degree, its threshold outperforms not only the RA and IRA codes but also the best known LDPC codes with the dame maximum node degree. Furthermore by puncturing the accumulators any desired high rate codes close to code rate 1 can be obtained with thresholds that stay close to the channel capacity thresholds uniformly. Iterative decoding simulation results are provided. The ARA codes also have projected graph or protograph representation that allows for high speed decoder implementation.

  17. Uplink Downlink Rate Balancing and Throughput Scaling in FDD Massive MIMO Systems

    NASA Astrophysics Data System (ADS)

    Bergel, Itsik; Perets, Yona; Shamai, Shlomo

    2016-05-01

    In this work we extend the concept of uplink-downlink rate balancing to frequency division duplex (FDD) massive MIMO systems. We consider a base station with large number antennas serving many single antenna users. We first show that any unused capacity in the uplink can be traded off for higher throughput in the downlink in a system that uses either dirty paper (DP) coding or linear zero-forcing (ZF) precoding. We then also study the scaling of the system throughput with the number of antennas in cases of linear Beamforming (BF) Precoding, ZF Precoding, and DP coding. We show that the downlink throughput is proportional to the logarithm of the number of antennas. While, this logarithmic scaling is lower than the linear scaling of the rate in the uplink, it can still bring significant throughput gains. For example, we demonstrate through analysis and simulation that increasing the number of antennas from 4 to 128 will increase the throughput by more than a factor of 5. We also show that a logarithmic scaling of downlink throughput as a function of the number of receive antennas can be achieved even when the number of transmit antennas only increases logarithmically with the number of receive antennas.

  18. Toward user mobility for OFDM-based visible light communications.

    PubMed

    Hong, Yang; Chen, Lian-Kuan

    2016-08-15

    We propose and experimentally demonstrate a mobile visible light communications (mobi-VLC) transmission system. The impact of user mobility on the performance of the mobi-VLC system is characterized, and we propose the use of the channel-independent orthogonal circulant matrix transform (OCT) precoding to combat the packet loss performance degradation induced by mobility. A mobile user terminal is used to detect the signal from a blue laser placed at 1 m away from the moving track. Various moving speeds (20, 40, 60, and 80  cm/s) and lateral moving distances (30, 40, and 50 cm) of the user terminal are investigated. The effectiveness of the OCT precoding is evaluated by the comparison with the conventional orthogonal frequency division multiplexing (OFDM) scheme and the adaptive-loaded discrete multi-tone (DMT) scheme. Experimental results show that the system performance degrades with the increase in user mobility speed and in moving distance. Furthermore, the OCT precoding provides performance improvement that is superior over that of conventional OFDM schemes, and it exhibits lower packet loss rate than that of adaptive-loaded DMT. No packet loss for 300  Mb/s transmission is achieved with a 30 cm lateral moving distance at 20  cm/s. PMID:27519083

  19. Leukotriene E4 is a full functional agonist for human cysteinyl leukotriene type 1 receptor-dependent gene expression

    PubMed Central

    Foster, Holly R.; Fuerst, Elisabeth; Branchett, William; Lee, Tak H.; Cousins, David J.; Woszczek, Grzegorz

    2016-01-01

    Leukotriene E4 (LTE4) the most stable of the cysteinyl leukotrienes (cysLTs) binds poorly to classical type 1 (CysLT1) and 2 (CysLT2) receptors although it induces potent responses in human airways in vivo, such as bronchoconstriction, airway hyperresponsiveness and inflammatory cell influx suggesting the presence of a novel receptor that preferentially responds to LTE4. To identify such a receptor two human mast cell lines, LAD2 and LUVA, were selected that differentially responded to LTE4 when analysed by intracellular signalling and gene expression. Comparative transcriptome analysis and recombinant gene overexpression experiments revealed CysLT1 as a receptor responsible for potent LTE4-induced response in LAD2 but not in LUVA cells, an observation confirmed further by gene knockdown and selective inhibitors. Lentiviral overexpression of CysLT1 in LUVA cells augmented intracellular calcium signalling induced by LTE4 but did not restore full agonist responses at the gene expression level. Our data support a model where both an increased expression of Gαq-coupled CysLT1, and sustained intracellular calcium mobilisation and extracellular signal-regulated kinase (Erk) activation, are required for LTE4-mediated regulation of gene expression in human cells. Our study shows for the first time that CysLT1 expression is critically important for responsiveness to LTE4 within a human cell system. PMID:26830450

  20. Copernicus observations of neutral helium lines in early-type stars

    NASA Astrophysics Data System (ADS)

    Dufton, P. L.; McKeith, C. D.

    1980-01-01

    Observations of stellar ultraviolet He I lines at 2829, 2945, and 3187 A obtained with the Copernicus Satellite, are compared with LTE and non-LTE calculations. The stars observed cover the range of spectral types O8-B7 and luminosity Classes I-V and were chosen to have relatively low projected rotational velocities. The equivalent widths measured with the two near ultraviolet Copernicus spectrometers (VI and V2) are in satisfactory accord both with each other and with results obtained from balloon flights and the IUE satellite. The model atmosphere calculations use the 'complete linearization procedure' and are similar to those of Auer and Mihalas (1973) but with a different choice of atomic data. For stars of Class II-V the observations and non-LTE calculations for the 2829 and 2945 A lines are in satisfactory agreement but there is an unresolved discrepancy for the 3187 A line. For the Class I supergiants neither LTE nor non-LTE theory reproduces the observations, in common with that found previously for visible triplet lines. In an appendix LTE and non-LTE equivalent widths are tabulated for T-sub-eff = 15,000 to 27,500 K and log 0 = 3 and 4.

  1. Collisional radiative model for heavy atoms in hot non-local-thermodynamical-equilibrium plasmas

    NASA Astrophysics Data System (ADS)

    Bar-Shalom, A.; Oreg, J.; Klapisch, M.

    1997-07-01

    A collisional radiative model for calculating non-local-thermodynamical-equilibrium (non-LTE) spectra of heavy atoms in hot plasmas has been developed, taking into account the numerous excited and autoionizing states. This model uses superconfigurations as effective levels with an iterative procedure which converges to the detailed configuration spectrum. The non-LTE opacities and emissivities may serve as a reliable benchmark for simpler on-line models in hydrodynamic code simulations. The model is tested against detailed configuration calculations of selenium and is applied to non-LTE optically thin plasma of lutetium.

  2. Computing NLTE Opacities -- Node Level Parallel Calculation

    SciTech Connect

    Holladay, Daniel

    2015-09-11

    Presentation. The goal: to produce a robust library capable of computing reasonably accurate opacities inline with the assumption of LTE relaxed (non-LTE). Near term: demonstrate acceleration of non-LTE opacity computation. Far term (if funded): connect to application codes with in-line capability and compute opacities. Study science problems. Use efficient algorithms that expose many levels of parallelism and utilize good memory access patterns for use on advanced architectures. Portability to multiple types of hardware including multicore processors, manycore processors such as KNL, GPUs, etc. Easily coupled to radiation hydrodynamics and thermal radiative transfer codes.

  3. High accuracy localization of long term evolution based on a new multiple carrier noise model.

    PubMed

    Lee, Wah Ching; Hung, Faan Hei; Tsang, Kim Fung; Wu, Chung Kit; Chi, Hao Ran; Chui, Kwok Tai; Lau, Wing Hong

    2014-01-01

    A high accuracy localization technique using Long Term Evolution (LTE) based on a new and accurate multiple carrier noise model has been developed. In the noise consideration, the LTE multiple carriers phase noise has been incorporated so that a new and accurate noise model is achieved. An experiment was performed to characterize the phase noise of carriers at 2 GHz. The developed noise model was incorporated into LTE localization analysis in a high traffic area in Hong Kong to evaluate the accuracy of localization. The evaluation and analysis reveals that the new localization method achieves an improvement of about 10% accuracy comparing to existing widely adopted schemes. PMID:25436658

  4. High Accuracy Localization of Long Term Evolution Based on a New Multiple Carrier Noise Model

    PubMed Central

    Lee, Wah Ching; Hung, Faan Hei; Tsang, Kim Fung; Wu, Chung Kit; Chi, Hao Ran; Chui, Kwok Tai; Lau, Wing Hong

    2014-01-01

    A high accuracy localization technique using Long Term Evolution (LTE) based on a new and accurate multiple carrier noise model has been developed. In the noise consideration, the LTE multiple carriers phase noise has been incorporated so that a new and accurate noise model is achieved. An experiment was performed to characterize the phase noise of carriers at 2 GHz. The developed noise model was incorporated into LTE localization analysis in a high traffic area in Hong Kong to evaluate the accuracy of localization. The evaluation and analysis reveals that the new localization method achieves an improvement of about 10% accuracy comparing to existing widely adopted schemes. PMID:25436658

  5. 15 CFR Supplement No. 5 to Part 742 - Encryption Registration

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    .../families of products: (a) Wireless (i) 3G cellular (ii) 4G cellular/WiMax/LTE (iii) Short-range wireless/WLAN (iv) Satellite (v) Radios (vi) Mobile communications, n.e.s. (b) Mobile applications (c)...

  6. 15 CFR Supplement No. 5 to Part 742 - Encryption Registration

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    .../families of products: (a) Wireless (i) 3G cellular (ii) 4G cellular/WiMax/LTE (iii) Short-range wireless/WLAN (iv) Satellite (v) Radios (vi) Mobile communications, n.e.s. (b) Mobile applications (c)...

  7. Exclusive single pion electroproduction off the proton in the high-lying resonances at Q2 < 5 GeV2 from CLAS

    SciTech Connect

    Park, Kijun

    2014-09-01

    The differential cross sections and structure functions for the exclusive electroproduction process ep --> e'n pi+ were measured in the range of the invariantmass for the np+ system 1.6 GeV lte W lte 2.0 GeV, and the photon virtuality 1.8 GeV2 lte Q2 lte 4.0 GeV2 using CLAS at Jefferson Lab. For the first time, these kinematics are probed in the exclusive p+ production from the protons with nearly full coverage in the azimuthal and polar angles of the np+ center-of-mass system. In this analysis, approximately 39,000 differential cross-section data points in terms of W, Q2, cosq theta* _ pi, and phi*_p-, were obtained. The preliminary differential cross section and structure function analyses are carried out, which allow us to extract the helicity amplitudes in high-lying resonances.

  8. Fast Inversion of Solar Ca II Spectra

    NASA Astrophysics Data System (ADS)

    Beck, C.; Choudhary, D. P.; Rezaei, R.; Louis, R. E.

    2015-01-01

    We present a fast (Lt1 s per profile) inversion code for solar Ca II lines. The code uses an archive of spectra that are synthesized prior to the inversion under the assumption of local thermodynamic equilibrium (LTE). We show that it can be successfully applied to spectrograph data or more sparsely sampled spectra from two-dimensional spectrometers. From a comparison to a non-LTE inversion of the same set of spectra, we derive a first-order non-LTE correction to the temperature stratifications derived in the LTE approach. The correction factor is close to unity up to log τ ~ -3 and increases to values of 2.5 and 4 at log τ = -6 in the quiet Sun and the umbra, respectively.

  9. Chromospheres of Luminous Cool Stars

    NASA Astrophysics Data System (ADS)

    Dupree, Andrea K.; Avrett, Eugene

    2015-08-01

    Ultraviolet imaging of Alpha Orionis (Betelgeuse) reveals a complex variable chromospheric structure. Such atmospheres in luminous cool stars can affect features in the optical spectrum. Constructing semi-empiricalmodel atmospheres of luminous stars including the temperature rise due to a chromosphere allows us to predict potential effects on optical transitions. The radiative transfer code, PANDORA, calculates line strengths in a LTE or non-LTE formulation, spherical symmetry, and includes velocity fields when present. Various aspects of the line calculations and their impact on equivalent widths will be discussed including developing appropriate chromospheric models, comparison to a pure radiative equilibrium model, transitions sensitive to non-LTE and the effects of a realistic spherical non-LTE approximation as compared to a plane-parallel approximation. We discuss the extent to which a chromosphere can impact the determination of stellar abundances.

  10. VizieR Online Data Catalog: Spectroscopy of WASP planet host stars (Doyle+, 2013)

    NASA Astrophysics Data System (ADS)

    Doyle, A. P.; Smalley, B.; Maxted, P. F. L.; Anderson, D. R.; Collier, Cameron A.; Gillon, M.; Hellier, C.; Pollacco, D.; Queloz, D.; Triaud, A. H. M. J.; West, R. G.

    2014-02-01

    The spectral synthesis package used was UCLSYN (University College London SYNthesis). ATLAS9 models atmospheres without convective overshooting are used and local thermodynamic equilibrium (LTE) is assumed. (2 data files).

  11. Quasi-thermal models

    NASA Technical Reports Server (NTRS)

    Delareza, Ramiro

    1987-01-01

    Non-local thermodynamics equilibrium (LTE) effects in the photosphere; recent research on the chromosphere of the M and C stars; and elementary shock-waves and pulsation theories and their applications to Mira long-period variables are discussed.

  12. A collisional-radiative average atom model for hot plasmas

    SciTech Connect

    Rozsnyai, B.F.

    1996-10-17

    A collisional-radiative `average atom` (AA) model is presented for the calculation of opacities of hot plasmas not in the condition of local thermodynamic equilibrium (LTE). The electron impact and radiative rate constants are calculated using the dipole oscillator strengths of the average atom. A key element of the model is the photon escape probability which at present is calculated for a semi infinite slab. The Fermi statistics renders the rate equation for the AA level occupancies nonlinear, which requires iterations until the steady state. AA level occupancies are found. Detailed electronic configurations are built into the model after the self-consistent non-LTE AA state is found. The model shows a continuous transition from the non-LTE to the LTE state depending on the optical thickness of the plasma. 22 refs., 13 figs., 1 tab.

  13. FAST INVERSION OF SOLAR Ca II SPECTRA

    SciTech Connect

    Beck, C.; Choudhary, D. P.; Rezaei, R.; Louis, R. E.

    2015-01-10

    We present a fast (<<1 s per profile) inversion code for solar Ca II lines. The code uses an archive of spectra that are synthesized prior to the inversion under the assumption of local thermodynamic equilibrium (LTE). We show that it can be successfully applied to spectrograph data or more sparsely sampled spectra from two-dimensional spectrometers. From a comparison to a non-LTE inversion of the same set of spectra, we derive a first-order non-LTE correction to the temperature stratifications derived in the LTE approach. The correction factor is close to unity up to log τ ∼ –3 and increases to values of 2.5 and 4 at log τ = –6 in the quiet Sun and the umbra, respectively.

  14. Spatiotemporal study of the local thermodynamic equilibrium deviations in high-intensity discharge lamps

    SciTech Connect

    Helali, H.; Bchir, T.; Araoud, Z.; Charrada, K.

    2013-04-15

    The aim of this work is to study the local thermodynamic equilibrium (LTE) deviations in arc discharges plasma generated in high-intensity discharge lamps operating under an ac (50 Hz) power supply. To achieve this goal, we elaborate a two-temperature, two-dimensional, and time-depending model. We have found numerical results almost reproducing the experimental data, which allows us to validate this model. After validation, we have discussed different energy term effects on the LTE deviations.

  15. On line contribution functions and examining spectral line formation in 3D model stellar atmospheres

    NASA Astrophysics Data System (ADS)

    Amarsi, A. M.

    2015-09-01

    Line contribution functions are useful diagnostics for studying spectral line formation in stellar atmospheres. I derive an expression for the contribution function to the absolute flux depression that emerges from three-dimensional `box-in-a-star' model stellar atmospheres. I illustrate the result by comparing the local thermodynamic equilibrium (LTE) spectral line formation of the high-excitation permitted OI 777 nm lines with the non-LTE case.

  16. Recoil Polarization for Neutral Pion Electroproduction near the Delta Resonance

    SciTech Connect

    Kelly, James J

    2003-10-01

    We have measured angular distributions for recoil polarization in the p(e,e'p)p0 reaction at Q2»1(GeV/c)2 with 1.16 |lte| W |lte|1.36 GeV across the D resonance. The data are compared with representative models and a truncated Legendre analysis is compared with a more general multipole analysis.

  17. Characterization of local thermodynamic equilibrium in a laser-induced aluminum alloy plasma.

    PubMed

    Zhang, Yong; Zhao, Zhenyang; Xu, Tao; Niu, GuangHui; Liu, Ying; Duan, Yixiang

    2016-04-01

    The electron temperature was evaluated using the line-to-continuum ratio method, and whether the plasma was close to the local thermodynamic equilibrium (LTE) state was investigated in detail. The results showed that approximately 5 μs after the plasma formed, the changes in the electron and excitation temperatures, which were determined using a Boltzmann plot, overlapped in the 15% error range, which indicated that the LTE state was reached. The recombination of electrons and ions and the free electron expansion process led to the deviation from the LTE state. The plasma's expansion rate slowed over time, and when the expansion time was close to the ionization equilibrium time, the LTE state was almost reached. The McWhirter criterion was adopted to calculate the threshold electron density for different species, and the results showed that experimental electron density was greater than the threshold electron density, which meant that the LTE state may have existed. However, for the nonmetal element N, the threshold electron density was greater than the value experimental value approximately 0.8 μs after the plasma formed, which meant that LTE state did not exist for N. PMID:27139680

  18. Rapid computation of spectrally integrated non-local thermodynamic equilibrium limb emission

    NASA Technical Reports Server (NTRS)

    Mlynczak, Martin G.; Olander, Daphne S.; Lopez-Puertas, Manuel

    1994-01-01

    The interpretation of infrared radiance measurements made by satellite-borne limb-scanning broadband radiometers requires accurate and computationally fast techniques with which to evaluate the equation of radiative transfer. This requirement is made even more stringent when analyzing measurements of non-local thermodynamic equilibrium (non-LTE) emission from the terrestrial mesosphere and lower thermosphere. In principle, line-by-line calculations which explicitly account for the departure from thermodynamic equilibrium in both the source functions and the transmittances are necessary. In this paper we extend the emissivity growth approximation (EGA) technique developed for local thermodynamic equilibrium (LTE) limb radiance for the molecular oxygen dayglow (1.27 micrometers and 762 nm), ozone and carbon dioxide in the 9- to 11-micrometer spectral interval, carbon monoxide (4.6 micrometers), nitric oxide (5.3 micrometers), and the carbon dioxide bands (15 micrometers) are presented. Using the non-LTE form of the EGA, the spectrally integrated limb emission is calculated for 35 tangent heights in the mesosphere and lower thermosphere (a total of 1200 atmospheric layers) with line-by-line accuracy in approximately 0.35 s of CPU time on readily available desktop computer hardware, while the corresponding line-by-line calculations may require several minutes. The non-LTE EGA technique will allow kinetic temperature and minor constituend retrieval algorithms to readily include non-LTE efects limited only by the a priori knowledge of the departure from LTE in the observed bands.

  19. Non-local thermodynamic equilibrium limb radiance from O3 and CO2 in the 9-11 micrometer spectral region

    NASA Technical Reports Server (NTRS)

    Edwards, David P.; Lopez-Puertas, Manuel; Mlynczak, Martin G.

    1994-01-01

    Satellite remote sensing of mesospheric and thermospheric O3 abundance in the terrestrial atmosphere often uses 9-11 micrometer thermal emission. In this paper, we apply a line-by-line non-local thermodynamic equilibrium (non-LTE) radiance model to this spectral region and investigate the conditions of LTE breakdown and the effect that this has on the limb radiance measured by an i.r. sounder. Monochromatic and band-integrated radiance calculations have been performed for limb view tangent heights between 55 and 105 km under daytime and nighttime conditions. Non-LTE emission from both O3 and CO2 are shown to be important with the divergence of radiance from LTE values and the diurnal variation being band dependent. We have shown that the contribution of the CO2 bands to the Limb Infrared Monitor of the Stratosphere O3 channel is significant for daytime conditions at tangent heights above about 60 km. A study has been made to choose O3 sounding channel spectral passbands for the High Resolution Dynamics Limb Sounder. High resolution calculations are required to determine those spectral intervals that will filter radiance from selected bands and characterize their non-LTE behavior. This will allow for improved O3 retrievals above 70 km and non-LTE studies.

  20. Identification of the major endogenous leukotriene metabolite in the bile of rats as N-acetyl leukotriene E4

    SciTech Connect

    Hagmann, W.; Denzlinger, C.; Rapp, S.; Weckbecker, G.; Keppler, D.

    1986-02-01

    Mercapturic acid formation, an established pathway in the detoxication of xenobiotics, is demonstrated for cysteinyl leukotrienes generated in rats in vivo after endotoxin treatment. The mercapturate N-acetyl-leukotriene E4 (N-acetyl-LTE4) represented a major metabolite eliminated into bile after injection of (/sup 3/H)LTC4 as shown by cochromatography with synthetic N-acetyl-LTE4 in four different HPLC solvent systems. The identity of endogenous N-acetyl-LTE4 elicited by endotoxin in vivo was additionally verified by enzymatic deacetylation followed by chemical N-acetylation. The deacetylation was catalyzed by penicillin amidase. Endogenous cysteinyl leukotrienes were quantified by radioimmunoassay after HPLC separation. A N-acetyl-LTE4 concentration of 80 nmol/l was determined in bile collected between 30 and 60 min after endotoxin injection. Under this condition, other cysteinyl leukotrienes detected in bile by radioimmunoassay amounted to less than 5% of N-acetyl-LTE4. The mercapturic acid pathway, leading from the glutathione conjugate LTC4 to N-acetyl-LTE4, thus plays an important role in the deactivation and elimination of these potent endogenous mediators.

  1. Erratum to: Relating Narrative, Inquiry, and Inscriptions: Supporting Consequential Play

    NASA Astrophysics Data System (ADS)

    Barab, Sasha A.; Sadler, Troy D.; Heiselt, Conan; Hickey, Daniel; Zuiker, Steven

    2010-08-01

    In this paper we describe our research using a multi-user virtual environment, Quest Atlantis, to embed fourth grade students in an aquatic habitat simulation. Specifically targeted towards engaging students in a rich inquiry investigation, we layered a socio-scientific narrative and an interactive rule set into a multi-user virtual environment gaming engine to establish a virtual world through which students learned about science inquiry, water quality concepts, and the challenges in balancing scientific and socio-economic factors. Overall, students were clearly engaged, participated in rich scientific discourse, submitted quality work, and learned science content. Further, through participation in this narrative, students developed a rich perceptual, conceptual, and ethical understanding of science. This study suggests that multi-user virtual worlds can be effectively leveraged to support academic content learning.

  2. Low complexity interference alignment algorithms for desired signal power maximization problem of MIMO channels

    NASA Astrophysics Data System (ADS)

    Sun, Cong; Yang, Yunchuan; Yuan, Yaxiang

    2012-12-01

    In this article, we investigate the interference alignment (IA) solution for a K-user MIMO interference channel. Proper users' precoders and decoders are designed through a desired signal power maximization model with IA conditions as constraints, which forms a complex matrix optimization problem. We propose two low complexity algorithms, both of which apply the Courant penalty function technique to combine the leakage interference and the desired signal power together as the new objective function. The first proposed algorithm is the modified alternating minimization algorithm (MAMA), where each subproblem has closed-form solution with an eigenvalue decomposition. To further reduce algorithm complexity, we propose a hybrid algorithm which consists of two parts. As the first part, the algorithm iterates with Householder transformation to preserve the orthogonality of precoders and decoders. In each iteration, the matrix optimization problem is considered in a sequence of 2D subspaces, which leads to one dimensional optimization subproblems. From any initial point, this algorithm obtains precoders and decoders with low leakage interference in short time. In the second part, to exploit the advantage of MAMA, it continues to iterate to perfectly align the interference from the output point of the first part. Analysis shows that in one iteration generally both proposed two algorithms have lower computational complexity than the existed maximum signal power (MSP) algorithm, and the hybrid algorithm enjoys lower complexity than MAMA. Simulations reveal that both proposed algorithms achieve similar performances as the MSP algorithm with less executing time, and show better performances than the existed alternating minimization algorithm in terms of sum rate. Besides, from the view of convergence rate, simulation results show that the MAMA enjoys fastest speed with respect to a certain sum rate value, while hybrid algorithm converges fastest to eliminate interference.

  3. Impaired degradation of leukotrienes in patients with peroxisome deficiency disorders.

    PubMed Central

    Mayatepek, E; Lehmann, W D; Fauler, J; Tsikas, D; Frölich, J C; Schutgens, R B; Wanders, R J; Keppler, D

    1993-01-01

    The degradation of leukotrienes by beta-oxidation from the omega-end proceeds in peroxisomes (Jedlitschky et al. J. Biol. Chem. 1991. 266:24763-24772). Peroxisomal degradation of leukotrienes was studied in humans by analyses of endogenous leukotrienes in urines from eight patients with biochemically established peroxisome deficiency disorder and eight age- and sex-matched healthy infant controls. Leukotriene metabolites were separated by high-performance liquid chromatography, quantified by radioimmunoassays, and identified as well as quantified by gas chromatography-mass spectrometry. Urinary leukotriene E4 (LTE4) and N-acetyl-LTE4 excretions, relative to creatinine, were increased > 10-fold in the patients in comparison to healthy infants. The beta-oxidation product omega-carboxy-tetranor-LTE3 averaged 0.05 mumol/mol creatinine in the controls but was not detectable in the patients. However, omega-carboxy-LTE4 (median 13.6 mumol/mol creatinine) was significantly increased in the patients' urine, whereas LTB4 (median 0.07 mumol/mol creatinine) and omega-carboxy-LTB4 were detected exclusively in the urines of the patients. These data indicate an impairment of the inactivation and degradation of both LTE4 and LTB4 in patients with peroxisomal deficiency. The increased levels of the biologically active, proinflammatory mediators LTE4 and LTB4 might be of pathophysiological significance in peroxisome deficiency disorders. This is the first and so far only condition with a pronounced urinary excretion of omega-carboxy-LTE4, omega-carboxy-LTB4, and LTB4. This impaired catabolism of leukotrienes and the altered pattern of metabolites may be of diagnostic value. These findings underline the essential role of peroxisomes in the catabolism of leukotrienes in humans. PMID:8450067

  4. Awareware: Narrowcasting Attributes for Selective Attention, Privacy, and Multipresence

    NASA Astrophysics Data System (ADS)

    Cohen, Michael; Newton Fernando, Owen Noel

    The domain of cscw, computer-supported collaborative work, and DSC, distributed synchronous collaboration, spans real-time interactive multiuser systems, shared information spaces, and applications for teleexistence and artificial reality, including collaborative virtual environments ( cves) (Benford et al., 2001). As presence awareness systems emerge, it is important to develop appropriate interfaces and architectures for managing multimodal multiuser systems. Especially in consideration of the persistent connectivity enabled by affordable networked communication, shared distributed environments require generalized control of media streams, techniques to control source → sink transmissions in synchronous groupware, including teleconferences and chatspaces, online role-playing games, and virtual concerts.

  5. Multi-pulse frequency shifted (MPFS) multiple access modulation for ultra wideband

    DOEpatents

    Nekoogar, Faranak; Dowla, Farid U.

    2012-01-24

    The multi-pulse frequency shifted technique uses mutually orthogonal short duration pulses o transmit and receive information in a UWB multiuser communication system. The multiuser system uses the same pulse shape with different frequencies for the reference and data for each user. Different users have a different pulse shape (mutually orthogonal to each other) and different transmit and reference frequencies. At the receiver, the reference pulse is frequency shifted to match the data pulse and a correlation scheme followed by a hard decision block detects the data.

  6. The Effect of Personality on Collaborative Task Performance and Interaction

    NASA Astrophysics Data System (ADS)

    Givney, Sinéad Mc; Smeaton, Alan F.; Lee, Hyowon

    Collocated, multi-user technologies, which support group-work are becoming increasingly popular. Examples include MERL’s Diamondtouch and Microsoft’s Surface, both of which have evolved from research prototypes to commercial products. Many applications have been developed for such technologies which support the work and entertainment needs of small groups of people. None of these applications however, have been studied in terms of the interactions and performances of their users with regards to their personality. In this paper, we address this research gap by conducting a series of user studies involving dyads working on a number of multi-user applications on the DiamondTouch tabletop device.

  7. Pulse Interval Modulation for Ultra-High Speed IR-UWB Communications Systems

    NASA Astrophysics Data System (ADS)

    Herceg, Marijan; Švedek, Tomislav; Matić, Tomislav

    2010-12-01

    This paper analyzes performances of the Pulse Interval Modulation (PIM) scheme for impulse radio ultra-wideband (IR-UWB) communication systems. Due to the PIM anisochronous nature, a tap delay line (TDL) coded division multiple access (CDMA) scheme based on strict optical orthogonal codes (SOOC) is proposed. This scheme is suitable for multiuser high-speed data asynchronous transmission applications because the average symbol length is shorter than in Pulse Position Modulation (PPM) schemes and it needs only chip synchronization. The error probability over the additive white Gaussian noise (AWGN) channel is derived in the single- and multi-user environment and compared with other modulation schemes.

  8. Knowledge-based image bandwidth compression and enhancement

    NASA Astrophysics Data System (ADS)

    Saghri, John A.; Tescher, Andrew G.

    1987-01-01

    Techniques for incorporating a priori knowledge in the digital coding and bandwidth compression of image data are described and demonstrated. An algorithm for identifying and highlighting thin lines and point objects prior to coding is presented, and the precoding enhancement of a slightly smoothed version of the image is shown to be more effective than enhancement of the original image. Also considered are readjustment of the local distortion parameter and variable-block-size coding. The line-segment criteria employed in the classification are listed in a table, and sample images demonstrating the effectiveness of the enhancement techniques are presented.

  9. Observational restrictions on sodium and aluminium abundance variations in evolution of the galaxy

    NASA Astrophysics Data System (ADS)

    Menzhevitski, V. S.; Shimanskaya, N. N.; Shimansky, V. V.; Sakhibullin, N. A.

    2013-07-01

    In this paper we construct and analyze the uniform non-LTE distributions of the aluminium ([Al/Fe]-[Fe/H]) and sodium ([Na/Fe]-[Fe/H]) abundances in the sample of 160 stars of the disk and halo of our Galaxy with metallicities within -4.07 ≤ [Fe/H] ≤ 0.28. The values of metallicity [Fe/H] and microturbulence velocity ξ turb indices are determined from the equivalent widths of the Fe II and Fe I lines. We estimated the sodium and aluminium abundances using a 21-level model of the Na I atom and a 39-level model of the Al I atom. The resulting LTE distributions of [Na/Fe]-[Fe/H] and [Al/Fe]-[Fe/H] do not correspond to the theoretical predictions of their evolution, suggesting that a non-LTE approach has to be applied to determine the abundances of these elements. The account of non-LTE corrections reduces by 0.05-0.15 dex the abundances of sodium, determined from the subordinate lines in the stars of the disk with [Fe/H] ≥ -2.0, and by 0.05-0.70 dex (with a strong dependence on metallicity) the abundances of [Na/Fe], determined by the resonance lines in the stars of the halo with [Fe/H] ≤ -2.0. The non-LTE corrections of the aluminium abundances are strictly positive and increase from 0.0-0.1 dex for the stars of the thin disk (-0.7 ≤ [Fe/H] ≤ 0.28) to 0.03-0.3 dex for the stars of the thick disk (-1.5 ≤ [Fe/H] ≤ -0.7) and 0.06-1.2 dex for the stars of the halo ([Fe/H] ≤ -2.0). The resulting non-LTE abundances of [Na/Fe] reveal a scatter of individual values up to Δ[Na/Fe] = 0.4 dex for the stars of close metallicities. The observed non-LTE distribution of [Na/Fe]-[Fe/H] within 0.15 dex coincides with the theoretical distributions of Samland and Kobayashi et al. The non-LTE aluminium abundances are characterized by a weak scatter of values (up to Δ[Al/Fe] = 0.2 dex) for the stars of all metallicities. The constructed non-LTE distribution of [Al/Fe]-[Fe/H] is in a satisfactory agreement to 0.2 dex with the theoretical data of Kobayashi et al., but

  10. Influence of inelastic collisions with hydrogen atoms on the formation of AlI and SiI lines in stellar spectra

    NASA Astrophysics Data System (ADS)

    Mashonkina, L. I.; Belyaev, A. K.; Shi, J.-R.

    2016-06-01

    We have performed calculations by abandoning the assumption of local thermodynamic equilibrium (within the so-called non-LTE approach) for Al I and Si I with model atmospheres corresponding to stars of spectral types F-G-Kwith differentmetal abundances. To take into account inelastic collisions with hydrogen atoms, for the first time we have applied the cross sections calculated by Belyaev et al. using model approaches within the formalism of the Born-Oppenheimer quantum theory. We show that for Al I non-LTE leads to higher ionization (overionization) than in LTE in the spectral line formation region and to a weakening of spectral lines, which is consistent with earlier non-LTE studies. However, our results, especially for the subordinate lines, differ quantitatively from the results of predecessors. Owing to their large cross sections, the ion-pair production and mutual neutralization processes Al I( nl) + HI(1 s) ↔ Al II(3 s 2) + H- provide a close coupling of highly excited Al I levels with the Al II ground state, which causes the deviations from the equilibrium level population to decrease compared to the calculations where the collisions only with electrons are taken into account. For three moderately metal-deficient dwarf stars, the aluminum abundance has been determined from seven Al I lines in different models of their formation. Under the assumption of LTE and in non-LTE calculations including the collisions only with electrons, the Al I 3961 ˚A resonance line gives a systematically lower abundance than the mean abundance from the subordinate lines, by 0.25-0.45 dex. The difference for each star is removed by taking into account the collisions with hydrogen atoms, and the rms error of the abundance derived from all seven Al I lines decreases by a factor of 1.5-3 compared to the LTE analysis. We have calculated the non- LTE corrections to the abundance for six subordinate Al I lines as a function of the effective temperature (4500 K ≤ T eff ≤ 6500 K

  11. A non-local thermodynamic equilibrium, line-blanketed synthetic spectrum of Iota Herculis - C, Al, and Si lines

    NASA Technical Reports Server (NTRS)

    Grigsby, James A.

    1991-01-01

    A non-LTE line-blanketed model stellar atmosphere is used to compute a model of I Herculis (B3 IV) with a Teff of 17,500 K and a log g of 3.75, following the conclusions of Peters and Polidan (1985). Detailed profiles of a number of lines of C, Al, and Si in the 1200-2000-A region are computed, including the resonance lines of C II, Al II, and Al III. These profiles are compared to observations obtained from the coaddition of eight IUE SWP images, using a technique developed by Leckrone and Adelman (1989). Comparison of carbon lines with a model that is underabundant in carbon by a factor of 2 relative to the sun indicates that the C abundance of Iota Her is at most one-half solar. Non-LTE effects are examined by comparing an LTE model possessing identical atmospheric parameters with the non-LTE model. Substantial differences in the populations of the model atomic states are found, but differences in the temperature structure of the two models often mask the non-LTE effects in the synthetic spectra.

  12. Mesospheric H2O Concentrations Retrieved from SABER/TIMED Measurements

    NASA Technical Reports Server (NTRS)

    Feofilov, A. G.; Marshall, B. T.; Garcia-Comas, M.; Kutepov, A. A.; Lopez-Puertas, M.; Manuilova, R. O.; Yankovsky, V.A.; Goldberg, R. A.; Gordley, L. L.; Petelin, S.; Russell, J. M., III

    2008-01-01

    The SABER instrument on board the TIMED Satellite is a limb scanning infrared radiometer designed to measure temperature and minor constituent vertical profiles and energetics parameters in the mesosphere and lower thermosphere (MLT). The H2O concentrations are retrieved from 6.3 micron band radiances. The populations of H2O(v2) vibrational levels are in non-Local Thermodynamic Equilibrium (non-LTE) above approximately 55 km altitude and the interpretation of 6.3 micron radiance requires utilizing non-LTE H2O model that includes various energy exchange processes in the system of H2O vibrational levels coupled with O2, N2, and CO2 vibrational levels. We incorporated these processes including kinetics of O2/O3 photolysis products to our research non-LTE H2O model and applied it for the development and optimization of SABER operational model. The latter has been validated using simultaneous SCISAT1/ACE occultation measurements. This helped us to estimate CO2(020)-O2(X,v=I), O2(X,v=I)- H2O(010), and O2(X,v=1) O rates at mesopause temperatures that is critical for an adequate interpretation of non-LTE H2O radiances in the MLT. The first distributions of seasonal and meridional H2O concentrations retrieved from SABER 6.3 micron radiances applying an updated non-LTE H2O model are demonstrated and discussed.

  13. Two-temperature transport coefficients of SF6-N2 plasma

    NASA Astrophysics Data System (ADS)

    Yang, Fei; Chen, Zhexin; Wu, Yi; Rong, Mingzhe; Guo, Anxiang; Liu, Zirui; Wang, Chunlin

    2015-10-01

    Sulfur hexafluoride (SF6) is widely adopted in electric power industry, especially in high-voltage circuit breakers and gas-insulated switchgear. However, the use of SF6 is limited by its high liquidation temperature and high global warming potential. Recently, research shows SF6-N2 mixture, which shows environmental friendliness and good electrical properties, may be a feasible substitute for pure SF6. This paper is devoted to the calculation of and transport coefficients of SF6-N2 mixture under both LTE (local thermodynamic equilibrium) and non-LTE condition. The two-temperature mass action law was used to determine the composition. The transport coefficients were calculated by classical Chapman-Enskog method simplified by Devoto. The thermophysical properties are presented for electron temperatures of 300-40 000 K, ratios of electron to heavy species temperature of 1-10 and N2 mole fraction of 0%-100% at atmospheric pressure. The ionization processes under both LTE and non-LTE have been discussed. The results show that deviations from local thermodynamic equilibrium significantly affect the properties of SF6-N2 plasma, especially before the plasma is fully ionized. The different influence of N2 on properties for SF6-N2 plasma in and out of LTE has been found. The results will serve as reliable reference data for computational simulation of the behavior of SF6-N2 plasmas.

  14. Beryllium abundances in Hg-Mn stars

    SciTech Connect

    Boesgaard, A.M.; Heacox, W.D.; Wolff, S.C.; Borsenberger, J.; Praderie, F.

    1982-08-15

    The Hg-Mn stars show anomalous line strengths of many chemical elements including Be. We have observed the Be ii resonance doublet at lambdalambda 3130, 3131 at 6.7 A mm/sup -1/ in 43 Hg-Mn stars and 10 normal stars in the same temperature range with the coude spectrograph of the 2.24 m University of Hawaii telescope at Mauna Kea. Measured equivalent widths of the two lines and/or the blend of the doublet have been compared with predictions from (1) LTE model atmospheres and (2) non-LTE line formation on non-LTE model atmospheres. (For strong Be ii lines, the LTE calculations result in more Be by factors of 2 to 4 than do the non-LTE calculations.) Overabundances of factors of 20--2 x 10/sup 4/ relative to solar have been found for 75% of the Hg-Mn stars. The 25% with little or no Be are typically among the cooler Hg-Mn stars, but for the stars with Be excesses, there is only marginal evidence for a correlationi of the size of the overabundance and temperature. It is suggested that diffusion driven by radiation pressure is responsible for the observed Be abundance anomalies.

  15. Getting the Picture on Image Databases: The Basics.

    ERIC Educational Resources Information Center

    Besser, Howard

    1995-01-01

    Outlines some of the major considerations in developing an image database system with an emphasis on continuous tone images and network-accessible multiuser databases. Topics include: definition/description of a digital image; matching technology to use; documentation/standards; access; image quality; software systems; scanners; and sources of…

  16. Creating New Mathematical Applications Utilizing SMART Table

    ERIC Educational Resources Information Center

    Seals, Cheryl D.; Swanier, Cheryl S.; Nyagwencha, Justus Nyamweya; Cagle, Ashley L.; Houser, Navorro

    2011-01-01

    SMART Technologies is leading the way for interactive learning, through their many different tools. The SMART Table is a multi-user, multi-touch interactive interface that not only teaches children different concepts in fun ways (Steurer P., 2003), but it also inspires cooperative competition. In Alabama, the state curriculum for kindergarten…

  17. Technology-Rich Ethnography for Examining the Transition to Authentic Problem-Solving in a High School Computer Programming Class

    ERIC Educational Resources Information Center

    Ge, Xun; Thomas, Michael K.; Greene, Barbara A.

    2006-01-01

    This study utilized elements of technology-rich ethnography to create a rich description of a multi-user virtual environment in a high school computer programming class. Of particular interest was the transition that took place in classroom culture from one characterized by a well-defined problem solving approach to one more indicative of open…

  18. Engaging Academically at Risk Primary School Students in an ICT Mediated after School Program

    ERIC Educational Resources Information Center

    Yong, Tay Lee; Ping, Lim Cher

    2008-01-01

    This case study documents how a group of 14 academically at risk Primary 5 students (11 year olds) were engaged in academic related tasks in an after school program mediated by a "3-D Multi-User Virtual Environment (MUVE)." Although there was no significant difference in the students' academic performance, they were found to be more engaged in the…

  19. Finding One's Own Space in Cyberspace.

    ERIC Educational Resources Information Center

    Bruckman, Amy

    1996-01-01

    Discusses the availability of virtual communities on the Internet. Stresses that there are online environments for nearly everyone, and offers advice for those designing new communities by relating experiences from the development of the specialized MediaMOO, a multiuser dungeon. Discusses restricting access, shaping development of the community,…

  20. A "Second Life" for Educators

    ERIC Educational Resources Information Center

    Waters, John K.

    2009-01-01

    In this article, the author talks about the 3D virtual world known as Second Life and its potential as a learning platform. In the last few years, many colleges, universities, and libraries have established resources in what has become the preeminent multiuser virtual environment. Today, more than 100 Second Life "regions" are used for educational…