Experimental research of adaptive OFDM and OCT precoding with a high SE for VLLC system

NASA Astrophysics Data System (ADS)

Liu, Shuang-ao; He, Jing; Chen, Qinghui; Deng, Rui; Zhou, Zhihua; Chen, Shenghai; Chen, Lin

2017-09-01

In this paper, an adaptive orthogonal frequency division multiplexing (OFDM) modulation scheme with 128/64/32/16-quadrature amplitude modulation (QAM) and orthogonal circulant matrix transform (OCT) precoding is proposed and experimentally demonstrated for a visible laser light communication (VLLC) system with a cost-effective 450-nm blue-light laser diode (LD). The performance of OCT precoding is compared with conventional the adaptive Discrete Fourier Transform-spread (DFT-spread) OFDM scheme, 32 QAM OCT precoding OFDM scheme, 64 QAM OCT precoding OFDM scheme and adaptive OCT precoding OFDM scheme. The experimental results show that OCT precoding can achieve a relatively flat signal-to-noise ratio (SNR) curve, and it can provide performance improvement in bit error rate (BER). Furthermore, the BER of the proposed OFDM signal with a raw bit rate 5.04 Gb/s after 5-m free space transmission is less than 20% of soft-decision forward error correlation (SD-FEC) threshold of 2.4 × 10-2, and the spectral efficiency (SE) of 4.2 bit/s/Hz can be successfully achieved.

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.

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.

Secure Image Transmission over DFT-precoded OFDM-VLC systems based on Chebyshev Chaos scrambling

NASA Astrophysics Data System (ADS)

Wang, Zhongpeng; Qiu, Weiwei

2017-08-01

This paper proposes a physical layer image secure transmission scheme for discrete Fourier transform (DFT) precoded OFDM-based visible light communication systems by using Chebyshev chaos maps. In the proposed scheme, 256 subcarriers and QPSK modulation are employed. The transmitted digital signal of the image is encrypted with a Chebyshev chaos sequence. The encrypted signal is then transformed by a DFT precoding matrix to reduce the PAPR of the OFDM signal. After that, the encrypted and DFT-precoded OFDM are transmitted over a VLC channel. The simulation results show that the proposed image security transmission scheme can not only protect the DFT-precoded OFDM-based VLC from eavesdroppers but also improve BER performance.

Optimal Power Allocation for Downstream xDSL With Per-Modem Total Power Constraints: Broadcast Channel Optimal Spectrum Balancing (BC-OSB)

NASA Astrophysics Data System (ADS)

Le Nir, Vincent; Moonen, Marc; Verlinden, Jan; Guenach, Mamoun

2009-02-01

Recently, the duality between Multiple Input Multiple Output (MIMO) Multiple Access Channels (MAC) and MIMO Broadcast Channels (BC) has been established under a total power constraint. The same set of rates for MAC can be achieved in BC exploiting the MAC-BC duality formulas while preserving the total power constraint. In this paper, we describe the BC optimal power allo- cation applying this duality in a downstream x-Digital Subscriber Lines (xDSL) context under a total power constraint for all modems over all tones. Then, a new algorithm called BC-Optimal Spectrum Balancing (BC-OSB) is devised for a more realistic power allocation under per-modem total power constraints. The capacity region of the primal BC problem under per-modem total power constraints is found by the dual optimization problem for the BC under per-modem total power constraints which can be rewritten as a dual optimization problem in the MAC by means of a precoder matrix based on the Lagrange multipliers. We show that the duality gap between the two problems is zero. The multi-user power allocation problem has been solved for interference channels and MAC using the OSB algorithm. In this paper we solve the problem of multi-user power allocation for the BC case using the OSB algorithm as well and we derive a computational efficient algorithm that will be referred to as BC-OSB. Simulation results are provided for two VDSL2 scenarios: the first one with Differential-Mode (DM) transmission only and the second one with both DM and Phantom- Mode (PM) transmissions.

Chaotic reconfigurable ZCMT precoder for OFDM data encryption and PAPR reduction

NASA Astrophysics Data System (ADS)

Chen, Han; Yang, Xuelin; Hu, Weisheng

2017-12-01

A secure orthogonal frequency division multiplexing (OFDM) transmission scheme precoded by chaotic Zadoff-Chu matrix transform (ZCMT) is proposed and demonstrated. It is proved that the reconfigurable ZCMT matrices after row/column permutations can be applied as an alternative precoder for peak-to-average power ratio (PAPR) reduction. The permutations and the reconfigurable parameters in ZCMT matrix are generated by a hyper digital chaos, in which a huge key space of ∼ 10800 is created for physical-layer OFDM data encryption. An encrypted data transmission of 8.9 Gb/s optical OFDM signals is successfully demonstrated over 20 km standard single-mode fiber (SSMF) for 16-QAM. The BER performance of the encrypted signals is improved by ∼ 2 dB (BER@ 10-3), which is mainly attributed to the effective reduction of PAPR via chaotic ZCMT precoding. Moreover, the chaotic ZCMT precoding scheme requires no sideband information, thus the spectrum efficiency is enhanced during transmission.

Semiblind channel estimation for MIMO-OFDM systems

NASA Astrophysics Data System (ADS)

Chen, Yi-Sheng; Song, Jyu-Han

2012-12-01

This article proposes a semiblind channel estimation method for multiple-input multiple-output orthogonal frequency-division multiplexing systems based on circular precoding. Relying on the precoding scheme at the transmitters, the autocorrelation matrix of the received data induces a structure relating the outer product of the channel frequency response matrix and precoding coefficients. This structure makes it possible to extract information about channel product matrices, which can be used to form a Hermitian matrix whose positive eigenvalues and corresponding eigenvectors yield the channel impulse response matrix. This article also tests the resistance of the precoding design to finite-sample estimation errors, and explores the effects of the precoding scheme on channel equalization by performing pairwise error probability analysis. The proposed method is immune to channel zero locations, and is reasonably robust to channel order overestimation. The proposed method is applicable to the scenarios in which the number of transmitters exceeds that of the receivers. Simulation results demonstrate the performance of the proposed method and compare it with some existing methods.

AMLSA Algorithm for Hybrid Precoding in Millimeter Wave MIMO Systems

NASA Astrophysics Data System (ADS)

Liu, Fulai; Sun, Zhenxing; Du, Ruiyan; Bai, Xiaoyu

2017-10-01

In this paper, an effective algorithm will be proposed for hybrid precoding in mmWave MIMO systems, referred to as alternating minimization algorithm with the least squares amendment (AMLSA algorithm). To be specific, for the fully-connected structure, the presented algorithm is exploited to minimize the classical objective function and obtain the hybrid precoding matrix. It introduces an orthogonal constraint to the digital precoding matrix which is amended subsequently by the least squares after obtaining its alternating minimization iterative result. Simulation results confirm that the achievable spectral efficiency of our proposed algorithm is better to some extent than that of the existing algorithm without the least squares amendment. Furthermore, the number of iterations is reduced slightly via improving the initialization procedure.

Digital transceiver design for two-way AF-MIMO relay systems with imperfect CSI

NASA Astrophysics Data System (ADS)

Hu, Chia-Chang; Chou, Yu-Fei; Chen, Kui-He

2013-09-01

In the paper, combined optimization of the terminal precoders/equalizers and single-relay precoder is proposed for an amplify-and-forward (AF) multiple-input multiple-output (MIMO) two-way single-relay system with correlated channel uncertainties. Both terminal transceivers and relay precoding matrix are designed based on the minimum mean square error (MMSE) criterion when terminals are unable to erase completely self-interference due to imperfect correlated channel state information (CSI). This robust joint optimization problem of beamforming and precoding matrices under power constraints belongs to neither concave nor convex so that a nonlinear matrix-form conjugate gradient (MCG) algorithm is applied to explore local optimal solutions. Simulation results show that the robust transceiver design is able to overcome effectively the loss of bit-error-rate (BER) due to inclusion of correlated channel uncertainties and residual self-interference.

Precoding based channel prediction for underwater acoustic OFDM

NASA Astrophysics Data System (ADS)

Cheng, En; Lin, Na; Sun, Hai-xin; Yan, Jia-quan; Qi, Jie

2017-04-01

The life duration of underwater cooperative network has been the hot topic in recent years. And the problem of node energy consuming is the key technology to maintain the energy balance among all nodes. To ensure energy efficiency of some special nodes and obtain a longer lifetime of the underwater cooperative network, this paper focuses on adopting precoding strategy to preprocess the signal at the transmitter and simplify the receiver structure. Meanwhile, it takes into account the presence of Doppler shifts and long feedback transmission delay in an underwater acoustic communication system. Precoding technique is applied based on channel prediction to realize energy saving and improve system performance. Different precoding methods are compared. Simulated results and experimental results show that the proposed scheme has a better performance, and it can provide a simple receiver and realize energy saving for some special nodes in a cooperative communication.

CSI Feedback Reduction for MIMO Interference Alignment

NASA Astrophysics Data System (ADS)

Rao, Xiongbin; Ruan, Liangzhong; Lau, Vincent K. N.

2013-09-01

Interference alignment (IA) is a linear precoding strategy that can achieve optimal capacity scaling at high SNR in interference networks. Most of the existing IA designs require full channel state information (CSI) at the transmitters, which induces a huge CSI signaling cost. Hence it is desirable to improve the feedback efficiency for IA and in this paper, we propose a novel IA scheme with a significantly reduced CSI feedback. To quantify the CSI feedback cost, we introduce a novel metric, namely the feedback dimension. This metric serves as a first-order measurement of CSI feedback overhead. Due to the partial CSI feedback constraint, conventional IA schemes can not be applied and hence, we develop a novel IA precoder / decorrelator design and establish new IA feasibility conditions. Via dynamic feedback profile design, the proposed IA scheme can also achieve a flexible tradeoff between the degree of freedom (DoF) requirements for data streams, the antenna resources and the CSI feedback cost. We show by analysis and simulations that the proposed scheme achieves substantial reductions of CSI feedback overhead under the same DoF requirement in MIMO interference networks.

A two layer chaotic encryption scheme of secure image transmission for DCT precoded OFDM-VLC transmission

NASA Astrophysics Data System (ADS)

Wang, Zhongpeng; Chen, Fangni; Qiu, Weiwei; Chen, Shoufa; Ren, Dongxiao

2018-03-01

In this paper, a two-layer image encryption scheme for a discrete cosine transform (DCT) precoded orthogonal frequency division multiplexing (OFDM) visible light communication (VLC) system is proposed. Firstly, in the proposed scheme the transmitted image is first encrypted by a chaos scrambling sequence,which is generated from the hybrid 4-D hyper- and Arnold map in the upper-layer. After that, the encrypted image is converted into digital QAM modulation signal, which is re-encrypted by chaos scrambling sequence based on Arnold map in physical layer to further enhance the security of the transmitted image. Moreover, DCT precoding is employed to improve BER performance of the proposed system and reduce the PAPR of OFDM signal. The BER and PAPR performances of the proposed system are evaluated by simulation experiments. The experiment results show that the proposed two-layer chaos scrambling schemes achieve image secure transmission for image-based OFDM VLC. Furthermore, DCT precoding can reduce the PAPR and improve the BER performance of OFDM-based VLC.

Estimation and Mitigation of Channel Non-Reciprocity in Massive MIMO

NASA Astrophysics Data System (ADS)

Raeesi, Orod; Gokceoglu, Ahmet; Valkama, Mikko

2018-05-01

Time-division duplex (TDD) based massive MIMO systems rely on the reciprocity of the wireless propagation channels when calculating the downlink precoders based on uplink pilots. However, the effective uplink and downlink channels incorporating the analog radio front-ends of the base station (BS) and user equipments (UEs) exhibit non-reciprocity due to non-identical behavior of the individual transmit and receive chains. When downlink precoder is not aware of such channel non-reciprocity (NRC), system performance can be significantly degraded due to NRC induced interference terms. In this work, we consider a general TDD-based massive MIMO system where frequency-response mismatches at both the BS and UEs, as well as the mutual coupling mismatch at the BS large-array system all coexist and induce channel NRC. Based on the NRC-impaired signal models, we first propose a novel iterative estimation method for acquiring both the BS and UE side NRC matrices and then also propose a novel NRC-aware downlink precoder design which utilizes the obtained estimates. Furthermore, an efficient pilot signaling scheme between the BS and UEs is introduced in order to facilitate executing the proposed estimation method and the NRC-aware precoding technique in practical systems. Comprehensive numerical results indicate substantially improved spectral efficiency performance when the proposed NRC estimation and NRC-aware precoding methods are adopted, compared to the existing state-of-the-art methods.

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,…

Construction of Protograph LDPC Codes with Linear Minimum Distance

NASA Technical Reports Server (NTRS)

Divsalar, Dariush; Dolinar, Sam; Jones, Christopher

2006-01-01

A construction method for protograph-based LDPC codes that simultaneously achieve low iterative decoding threshold and linear minimum distance is proposed. We start with a high-rate protograph LDPC code with variable node degrees of at least 3. Lower rate codes are obtained by splitting check nodes and connecting them by degree-2 nodes. This guarantees the linear minimum distance property for the lower-rate codes. Excluding checks connected to degree-1 nodes, we show that the number of degree-2 nodes should be at most one less than the number of checks for the protograph LDPC code to have linear minimum distance. Iterative decoding thresholds are obtained by using the reciprocal channel approximation. Thresholds are lowered by using either precoding or at least one very high-degree node in the base protograph. A family of high- to low-rate codes with minimum distance linearly increasing in block size and with capacity-approaching performance thresholds is presented. FPGA simulation results for a few example codes show that the proposed codes perform as predicted.

"Folksonomy" and the Restructuring of Writing Space

ERIC Educational Resources Information Center

Nicotra, Jodie

2009-01-01

Metaphors that posit writing as linear, essayistic, and the province of a single author no longer fit the dynamic, newly spatialized practices of composition occurring on and via the Web. Using "folksonomy," or multi-user tagging, as an example of one of these practices, this article argues for a new metaphor for writing that encapsulates how…

Interference Alignment With Partial CSI Feedback in MIMO Cellular Networks

NASA Astrophysics Data System (ADS)

Rao, Xiongbin; Lau, Vincent K. N.

2014-04-01

Interference alignment (IA) is a linear precoding strategy that can achieve optimal capacity scaling at high SNR in interference networks. However, most existing IA designs require full channel state information (CSI) at the transmitters, which would lead to significant CSI signaling overhead. There are two techniques, namely CSI quantization and CSI feedback filtering, to reduce the CSI feedback overhead. In this paper, we consider IA processing with CSI feedback filtering in MIMO cellular networks. We introduce a novel metric, namely the feedback dimension, to quantify the first order CSI feedback cost associated with the CSI feedback filtering. The CSI feedback filtering poses several important challenges in IA processing. First, there is a hidden partial CSI knowledge constraint in IA precoder design which cannot be handled using conventional IA design methodology. Furthermore, existing results on the feasibility conditions of IA cannot be applied due to the partial CSI knowledge. Finally, it is very challenging to find out how much CSI feedback is actually needed to support IA processing. We shall address the above challenges and propose a new IA feasibility condition under partial CSIT knowledge in MIMO cellular networks. Based on this, we consider the CSI feedback profile design subject to the degrees of freedom requirements, and we derive closed-form trade-off results between the CSI feedback cost and IA performance in MIMO cellular networks.

Equivalent ZF precoding scheme for downlink indoor MU-MIMO VLC systems

NASA Astrophysics Data System (ADS)

Fan, YangYu; Zhao, Qiong; Kang, BoChao; Deng, LiJun

2018-01-01

In indoor visible light communication (VLC) systems, the channels of photo detectors (PDs) at one user are highly correlated, which determines the choice of spatial diversity model for individual users. In a spatial diversity model, the signals received by PDs belonging to one user carry the same information, and can be combined directly. Based on the above, we propose an equivalent zero-forcing (ZF) precoding scheme for multiple-user multiple-input single-output (MU-MIMO) VLC systems by transforming an indoor MU-MIMO VLC system into an indoor multiple-user multiple-input single-output (MU-MISO) VLC system through simply processing. The power constraints of light emitting diodes (LEDs) are also taken into account. Comprehensive computer simulations in three scenarios indicate that our scheme can not only reduce the computational complexity, but also guarantee the system performance. Furthermore, the proposed scheme does not require noise information in the calculating of the precoding weights, and has no restrictions on the numbers of APs and PDs.

Pre-coding assisted generation of a frequency quadrupled optical vector D-band millimeter wave with one Mach-Zehnder modulator.

PubMed

Zhou, Wen; Li, Xinying; Yu, Jianjun

2017-10-30

We propose QPSK millimeter-wave (mm-wave) vector signal generation for D-band based on balanced precoding-assisted photonic frequency quadrupling technology employing a single intensity modulator without an optical filter. The intensity MZM is driven by a balanced pre-coding 37-GHz QPSK RF signal. The modulated optical subcarriers are directly sent into the single ended photodiode to generate 148-GHz QPSK vector signal. We experimentally demonstrate 1-Gbaud 148-GHz QPSK mm-wave vector signal generation, and investigate the bit-error-rate (BER) performance of the vector signals at 148-GHz. The experimental results show that the BER value can be achieved as low as 1.448 × 10 -3 when the optical power into photodiode is 8.8dBm. To the best of our knowledge, it is the first time to realize the frequency-quadrupling vector mm-wave signal generation at D-band based on only one MZM without an optical filter.

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.

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.

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.

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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.

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.

Multiuse trail intersection safety analysis: A crowdsourced data perspective.

PubMed

Jestico, Ben; Nelson, Trisalyn A; Potter, Jason; Winters, Meghan

2017-06-01

Real and perceived concerns about cycling safety are a barrier to increased ridership in many cities. Many people prefer to bike on facilities separated from motor vehicles, such as multiuse trails. However, due to underreporting, cities lack data on bike collisions, especially along greenways and multiuse paths. We used a crowdsourced cycling incident dataset (2005-2016) from BikeMaps.org for the Capital Regional District (CRD), BC, Canada. Our goal was to identify design characteristics associated with unsafe intersections between multiuse trails and roads. 92.8% of mapped incidents occurred between 2014 and 2016. We extracted both collision and near miss incidents at intersections from BikeMaps.org. We conducted site observations at 32 intersections where a major multiuse trail intersected with roads. We compared attributes of reported incidents at multiuse trail-road intersections to those at road-road intersections. We then used negative binomial regression to model the relationship between the number of incidents and the infrastructure characteristics at multiuse trail-road intersections. We found a higher proportion of collisions (38%, or 17/45 total reports) at multiuse trail-road intersections compared to road-road intersections (23%, or 62/268 total reports). A higher proportion of incidents resulted in an injury at multiuse trail-road intersections compared to road-road intersections (33% versus 15%). Cycling volumes, vehicle volumes, and trail sight distance were all associated with incident frequency at multiuse trail-road intersections. Supplementing traditional crash records with crowdsourced cycling incident data provides valuable evidence on cycling safety at intersections between multiuse trails and roads, and more generally, when conflicts occur between diverse transportation modes. Copyright © 2017. Published by Elsevier Ltd.

Protograph based LDPC codes with minimum distance linearly growing with block size

NASA Technical Reports Server (NTRS)

Divsalar, Dariush; Jones, Christopher; Dolinar, Sam; Thorpe, Jeremy

2005-01-01

We propose several LDPC code constructions that simultaneously achieve good threshold and error floor performance. Minimum distance is shown to grow linearly with block size (similar to regular codes of variable degree at least 3) by considering ensemble average weight enumerators. Our constructions are based on projected graph, or protograph, structures that support high-speed decoder implementations. As with irregular ensembles, our constructions are sensitive to the proportion of degree-2 variable nodes. A code with too few such nodes tends to have an iterative decoding threshold that is far from the capacity threshold. A code with too many such nodes tends to not exhibit a minimum distance that grows linearly in block length. In this paper we also show that precoding can be used to lower the threshold of regular LDPC codes. The decoding thresholds of the proposed codes, which have linearly increasing minimum distance in block size, outperform that of regular LDPC codes. Furthermore, a family of low to high rate codes, with thresholds that adhere closely to their respective channel capacity thresholds, is presented. Simulation results for a few example codes show that the proposed codes have low error floors as well as good threshold SNFt performance.

Bilinear modeling of EMG signals to extract user-independent features for multiuser myoelectric interface.

PubMed

Matsubara, Takamitsu; Morimoto, Jun

2013-08-01

In this study, we propose a multiuser myoelectric interface that can easily adapt to novel users. When a user performs different motions (e.g., grasping and pinching), different electromyography (EMG) signals are measured. When different users perform the same motion (e.g., grasping), different EMG signals are also measured. Therefore, designing a myoelectric interface that can be used by multiple users to perform multiple motions is difficult. To cope with this problem, we propose for EMG signals a bilinear model that is composed of two linear factors: 1) user dependent and 2) motion dependent. By decomposing the EMG signals into these two factors, the extracted motion-dependent factors can be used as user-independent features. We can construct a motion classifier on the extracted feature space to develop the multiuser interface. For novel users, the proposed adaptation method estimates the user-dependent factor through only a few interactions. The bilinear EMG model with the estimated user-dependent factor can extract the user-independent features from the novel user data. We applied our proposed method to a recognition task of five hand gestures for robotic hand control using four-channel EMG signals measured from subject forearms. Our method resulted in 73% accuracy, which was statistically significantly different from the accuracy of standard nonmultiuser interfaces, as the result of a two-sample t -test at a significance level of 1%.

Precluding nonlinear ISI in direct detection long-haul fiber optic systems

NASA Technical Reports Server (NTRS)

Swenson, Norman L.; Shoop, Barry L.; Cioffi, John M.

1991-01-01

Long-distance, high-rate fiber optic systems employing directly modulated 1.55-micron single-mode lasers and conventional single-mode fiber suffer severe intersymbol interference (ISI) with a large nonlinear component. A method of reducing the nonlinearity of the ISI, thereby making linear equalization more viable, is investigated. It is shown that the degree of nonlinearity is highly dependent on the choice of laser bias current, and that in some cases the ISI nonlinearity can be significantly reduced by biasing the laser substantially above threshold. Simulation results predict that an increase in signal-to-nonlinear-distortion ratio as high as 25 dB can be achieved for synchronously spaced samples at an optimal sampling phase by increasing the bias current from 1.2 times threshold to 3.5 times threshold. The high SDR indicates that a linear tapped delay line equalizer could be used to mitigate ISI. Furthermore, the shape of the pulse response suggests that partial response precoding and digital feedback equalization would be particularly effective for this channel.

Differential Characteristics Based Iterative Multiuser Detection for Wireless Sensor Networks

PubMed Central

Chen, Xiaoguang; Jiang, Xu; Wu, Zhilu; Zhuang, Shufeng

2017-01-01

High throughput, low latency and reliable communication has always been a hot topic for wireless sensor networks (WSNs) in various applications. Multiuser detection is widely used to suppress the bad effect of multiple access interference in WSNs. In this paper, a novel multiuser detection method based on differential characteristics is proposed to suppress multiple access interference. The proposed iterative receive method consists of three stages. Firstly, a differential characteristics function is presented based on the optimal multiuser detection decision function; then on the basis of differential characteristics, a preliminary threshold detection is utilized to find the potential wrongly received bits; after that an error bit corrector is employed to correct the wrong bits. In order to further lower the bit error ratio (BER), the differential characteristics calculation, threshold detection and error bit correction process described above are iteratively executed. Simulation results show that after only a few iterations the proposed multiuser detection method can achieve satisfactory BER performance. Besides, BER and near far resistance performance are much better than traditional suboptimal multiuser detection methods. Furthermore, the proposed iterative multiuser detection method also has a large system capacity. PMID:28212328

A new precoding scheme for spectral efficient optical OFDM systems

NASA Astrophysics Data System (ADS)

Hardan, Saad Mshhain; Bayat, Oguz; Abdulkafi, Ayad Atiyah

2018-07-01

Achieving high spectral efficiency is the key requirement of 5G and optical wireless communication systems and has recently attracted much attention, aiming to satisfy the ever increasing demand for high data rates in communications systems. In this paper, we propose a new precoding/decoding algorithm for spectral efficient optical orthogonal frequency division multiplexing (OFDM) scheme based visible light communication (VLC) systems. The proposed coded modulated optical (CMO) based OFDM system can be applied for both single input single output (SISO) and multiple input multiple-output (MIMO) architectures. Firstly, the real OFDM time domain signal is obtained through invoking the precoding/decoding algorithm without the Hermitian symmetry. After that, the positive signal is achieved either by adding a DC-bias or by using the spatial multiplexing technique. The proposed CMO-OFDM scheme efficiently improves the spectral efficiency of the VLC system as it does not require the Hermitian symmetry constraint to yield real signals. A comparison of the performance improvement of the proposed scheme with other OFDM approaches is also presented in this work. Simulation results show that the proposed CMO-OFDM scheme can not only enhance the spectral efficiency of OFDM-based VLC systems but also improve bit error rate (BER) performance compared with other optical OFDM schemes.

Performance Analysis of Iterative Channel Estimation and Multiuser Detection in Multipath DS-CDMA Channels

NASA Astrophysics Data System (ADS)

Li, Husheng; Betz, Sharon M.; Poor, H. Vincent

2007-05-01

This paper examines the performance of decision feedback based iterative channel estimation and multiuser detection in channel coded aperiodic DS-CDMA systems operating over multipath fading channels. First, explicit expressions describing the performance of channel estimation and parallel interference cancellation based multiuser detection are developed. These results are then combined to characterize the evolution of the performance of a system that iterates among channel estimation, multiuser detection and channel decoding. Sufficient conditions for convergence of this system to a unique fixed point are developed.

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.

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.

Proposal for Implementing Multi-User Database (MUD) Technology in an Academic Library.

ERIC Educational Resources Information Center

Filby, A. M. Iliana

1996-01-01

Explores the use of MOO (multi-user object oriented) virtual environments in academic libraries to enhance reference services. Highlights include the development of multi-user database (MUD) technology from gaming to non-recreational settings; programming issues; collaborative MOOs; MOOs as distinguished from other types of virtual reality; audio…

Experimental demonstration of an OFDM based visible light communication system using inter-block precoding and superimposed pilots

NASA Astrophysics Data System (ADS)

Zhang, Junwei; Hong, Xuezhi; Liu, Jie; Guo, Changjian

2018-04-01

In this work, we investigate and experimentally demonstrate an orthogonal frequency division multiplexing (OFDM) based high speed wavelength-division multiplexed (WDM) visible light communication (VLC) system using an inter-block data precoding and superimposed pilots (DP-SP) based channel estimation (CE) scheme. The residual signal-to-pilot interference (SPI) can be eliminated by using inter-block data precoding, resulting in a significant improvement in estimated accuracy and the overall system performance compared with uncoded SP based CE scheme. We also study the power allocation/overhead problem of the training for DP-SP, uncoded SP and conventional preamble based CE schemes, from which we obtain the optimum signal-to-pilot power ratio (SPR)/overhead percentage for all above cases. Intra-symbol frequency-domain averaging (ISFA) is also adopted to further enhance the accuracy of CE. By using the DP-SP based CE scheme, aggregate data rates of 1.87-Gbit/s and 1.57-Gbit/s are experimentally demonstrated over 0.8-m and 2-m indoor free space transmission, respectively, using a commercially available red, green and blue (RGB) light emitting diode (LED) with WDM. Experimental results show that the DP-SP based CE scheme is comparable to the conventional preamble based CE scheme in term of received Q factor and data rate while entailing a much smaller overhead-size.

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.

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.

Experimental demonstration of the transmission performance for LDPC-coded multiband OFDM ultra-wideband over fiber system

NASA Astrophysics Data System (ADS)

He, Jing; Wen, Xuejie; Chen, Ming; Chen, Lin; Su, Jinshu

2015-01-01

To improve the transmission performance of multiband orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) over optical fiber, a pre-coding scheme based on low-density parity-check (LDPC) is adopted and experimentally demonstrated in the intensity-modulation and direct-detection MB-OFDM UWB over fiber system. Meanwhile, a symbol synchronization and pilot-aided channel estimation scheme is implemented on the receiver of the MB-OFDM UWB over fiber system. The experimental results show that the LDPC pre-coding scheme can work effectively in the MB-OFDM UWB over fiber system. After 70 km standard single-mode fiber (SSMF) transmission, at the bit error rate of 1 × 10-3, the receiver sensitivities are improved about 4 dB when the LDPC code rate is 75%.

An Efficient Downlink Scheduling Strategy Using Normal Graphs for Multiuser MIMO Wireless Systems

NASA Astrophysics Data System (ADS)

Chen, Jung-Chieh; Wu, Cheng-Hsuan; Lee, Yao-Nan; Wen, Chao-Kai

Inspired by the success of the low-density parity-check (LDPC) codes in the field of error-control coding, in this paper we propose transforming the downlink multiuser multiple-input multiple-output scheduling problem into an LDPC-like problem using the normal graph. Based on the normal graph framework, soft information, which indicates the probability that each user will be scheduled to transmit packets at the access point through a specified angle-frequency sub-channel, is exchanged among the local processors to iteratively optimize the multiuser transmission schedule. Computer simulations show that the proposed algorithm can efficiently schedule simultaneous multiuser transmission which then increases the overall channel utilization and reduces the average packet delay.

Orthogonal Array Testing for Transmit Precoding based Codebooks in Space Shift Keying Systems

NASA Astrophysics Data System (ADS)

Al-Ansi, Mohammed; Alwee Aljunid, Syed; Sourour, Essam; Mat Safar, Anuar; Rashidi, C. B. M.

2018-03-01

In Space Shift Keying (SSK) systems, transmit precoding based codebook approaches have been proposed to improve the performance in limited feedback channels. The receiver performs an exhaustive search in a predefined Full-Combination (FC) codebook to select the optimal codeword that maximizes the Minimum Euclidean Distance (MED) between the received constellations. This research aims to reduce the codebook size with the purpose of minimizing the selection time and the number of feedback bits. Therefore, we propose to construct the codebooks based on Orthogonal Array Testing (OAT) methods due to their powerful inherent properties. These methods allow to acquire a short codebook where the codewords are sufficient to cover almost all the possible effects included in the FC codebook. Numerical results show the effectiveness of the proposed OAT codebooks in terms of the system performance and complexity.

Performance Evaluation of Analog Beamforming with Hardware Impairments for mmW Massive MIMO Communication in an Urban Scenario.

PubMed

Gimenez, Sonia; Roger, Sandra; Baracca, Paolo; Martín-Sacristán, David; Monserrat, Jose F; Braun, Volker; Halbauer, Hardy

2016-09-22

The use of massive multiple-input multiple-output (MIMO) techniques for communication at millimeter-Wave (mmW) frequency bands has become a key enabler to meet the data rate demands of the upcoming fifth generation (5G) cellular systems. In particular, analog and hybrid beamforming solutions are receiving increasing attention as less expensive and more power efficient alternatives to fully digital precoding schemes. Despite their proven good performance in simple setups, their suitability for realistic cellular systems with many interfering base stations and users is still unclear. Furthermore, the performance of massive MIMO beamforming and precoding methods are in practice also affected by practical limitations and hardware constraints. In this sense, this paper assesses the performance of digital precoding and analog beamforming in an urban cellular system with an accurate mmW channel model under both ideal and realistic assumptions. The results show that analog beamforming can reach the performance of fully digital maximum ratio transmission under line of sight conditions and with a sufficient number of parallel radio-frequency (RF) chains, especially when the practical limitations of outdated channel information and per antenna power constraints are considered. This work also shows the impact of the phase shifter errors and combiner losses introduced by real phase shifter and combiner implementations over analog beamforming, where the former ones have minor impact on the performance, while the latter ones determine the optimum number of RF chains to be used in practice.

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…

Blind information-theoretic multiuser detection algorithms for DS-CDMA and WCDMA downlink systems.

PubMed

Waheed, Khuram; Salem, Fathi M

2005-07-01

Code division multiple access (CDMA) is based on the spread-spectrum technology and is a dominant air interface for 2.5G, 3G, and future wireless networks. For the CDMA downlink, the transmitted CDMA signals from the base station (BS) propagate through a noisy multipath fading communication channel before arriving at the receiver of the user equipment/mobile station (UE/MS). Classical CDMA single-user detection (SUD) algorithms implemented in the UE/MS receiver do not provide the required performance for modern high data-rate applications. In contrast, multi-user detection (MUD) approaches require a lot of a priori information not available to the UE/MS. In this paper, three promising adaptive Riemannian contra-variant (or natural) gradient based user detection approaches, capable of handling the highly dynamic wireless environments, are proposed. The first approach, blind multiuser detection (BMUD), is the process of simultaneously estimating multiple symbol sequences associated with all the users in the downlink of a CDMA communication system using only the received wireless data and without any knowledge of the user spreading codes. This approach is applicable to CDMA systems with relatively short spreading codes but becomes impractical for systems using long spreading codes. We also propose two other adaptive approaches, namely, RAKE -blind source recovery (RAKE-BSR) and RAKE-principal component analysis (RAKE-PCA) that fuse an adaptive stage into a standard RAKE receiver. This adaptation results in robust user detection algorithms with performance exceeding the linear minimum mean squared error (LMMSE) detectors for both Direct Sequence CDMA (DS-CDMA) and wide-band CDMA (WCDMA) systems under conditions of congestion, imprecise channel estimation and unmodeled multiple access interference (MAI).

Dual-tone optical vector millimeter wave signal generated by frequency-nonupling the radio frequency 16-star quadrature-amplitude-modulation signal

NASA Astrophysics Data System (ADS)

Wu, Tonggen; Ma, Jianxin

2017-12-01

This paper proposes an original scheme to generate the photonic dual-tone optical millimeter wave (MMW) carrying the 16-star quadrature-amplitude-modulation (QAM) signal via an optical phase modulator (PM) and an interleaver with adaptive photonic frequency-nonupling without phase precoding. To enable the generated optical vector MMW signal to resist the power fading effect caused by the fiber chromatic dispersion, the modulated -5th- and +4th-order sidebands are selected from the output of the PM, which is driven by the precoding 16-star QAM signal. The modulation index of the PM is optimized to gain the maximum opto-electrical conversion efficiency. A radio over fiber link is built by simulation, and the simulated constellations and the bit error rate graph demonstrate that the frequency-nonupling 16-star QAM MMW signal has good transmission performance. The simulation results agree well with our theoretical results.

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.

Usability testing of a prototype multi-user telehealth kiosk.

PubMed

Courtney, Karen L; Matthews, Judith T; McMillan, Julie M; Person Mecca, Laurel; Smailagic, Asim; Siewiorek, Daniel

2015-01-01

The overall purpose of this study was to learn how community-dwelling older adults would interact with our prototype multi-user telehealth kiosk and their views about its usability. Seven subjects participated in laboratory-based usability sessions to evaluate the physical design, appearance, functionality and perceived ease of use of a multi-user telehealth kiosk prototype. During usability testing participants recommended 18 new features (29% of comments), identified 15 software errors (23% of comments) and 29 user interface errors (47% of comments).

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.

Multi-user Droplet Combustion Apparatus (MDCA) Hardware Replacement

NASA Image and Video Library

2013-10-02

ISS037-E-004956 (2 Oct. 2013) --- NASA astronaut Karen Nyberg, Expedition 37 flight engineer, performs the Multi-user Droplet Combustion Apparatus (MDCA) hardware replacement in the Harmony node of the International Space Station.

Multi-user Droplet Combustion Apparatus (MDCA) Hardware Replacement

NASA Image and Video Library

2013-10-02

ISS037-E-004959 (2 Oct. 2013) --- NASA astronaut Karen Nyberg, Expedition 37 flight engineer, performs the Multi-user Droplet Combustion Apparatus (MDCA) hardware replacement in the Harmony node of the International Space Station.

Design of simplified maximum-likelihood receivers for multiuser CPM systems.

PubMed

Bing, Li; Bai, Baoming

2014-01-01

A class of simplified maximum-likelihood receivers designed for continuous phase modulation based multiuser systems is proposed. The presented receiver is built upon a front end employing mismatched filters and a maximum-likelihood detector defined in a low-dimensional signal space. The performance of the proposed receivers is analyzed and compared to some existing receivers. Some schemes are designed to implement the proposed receivers and to reveal the roles of different system parameters. Analysis and numerical results show that the proposed receivers can approach the optimum multiuser receivers with significantly (even exponentially in some cases) reduced complexity and marginal performance degradation.

Interference-Assisted Techniques for Transmission and Multiple Access in Optical Communications

NASA Astrophysics Data System (ADS)

Guan, Xun

Optical communications can be in wired or wireless form. Fiber optics communication (FOC) connects transmitters and receivers with optical fiber. Benefiting from its high bandwidth, low cost per volume and stability, it gains a significant market share in long-haul networks, access networks and data centers. Meanwhile, optical wireless communication (OWC) is also emerging as a crucial player in the communication market. In OWC, free-space optical communication (FSO) and visible light communication (VLC) are being studied and commercially deployed extensively. Interference is a common phenomenon in multi-user communication systems. In both FOC and OWC, interference has long been treated as a detrimental effect. However, it could also be beneficial to system applications. The effort of harnessing interference has spurred numerous innovations. Interesting examples are physical-layer network coding (PNC) and non-orthogonal multiple access (NOMA). The first part of this thesis in on the topic of PNC. PNC was firstly proposed in wireless communication to improve the throughput of a two-way relay network (TWRN). As a variation of network coding (NC), PNC turns the common channel interference (CCI) as a natural network coding operation. In this thesis, PNC is introduced into optical communication. Three schemes are proposed in different scenarios. Firstly, PNC is applied to a coherent optical orthogonal frequency division multiplexing (CO-OFDM) system so as to improve the throughput of the multicast network. The optical signal to noise ratio (OSNR) penalty is quite low. Secondly, we investigate the application of PNC in an OFDM passive optical network (OFDM-PON) supporting heterogeneous services. It is found that only minor receiver power penalties are observed to realize PNC-based virtual private networks (VPN), both in the wired service part and the wireless service part in an OFDM-PON with heterogeneous services. Thirdly, we innovate relay-based visible light communication (VLC) by adopting PNC, with a newly proposed phase-aligning method. PNC could improve the throughput at the bottlenecking relay node in a VLC system, and the proposed phase aligning method can improve the BER performance. The second part of this thesis discusses another interference-assisted technology in communication, that is, non-orthogonal multiple access (NOMA). NOMA multiplexes signals from multiple users in another dimension: power domain, with a non-orthogonal multiplexing in other dimensions such as time, frequency and code. Three schemes are proposed in this part. The first and the second schemes both realize NOMA in VLC, with different multiuser detection (MUD) techniques and a proposed phase pre-distortion method. Although both can decrease the system BER compared to conventional NOMA, the scheme using joint detection (JD) outperforms the one using successive interference cancellation (SIC). The third scheme investigated in this part is a combination of NOMA and a multicarrier precoding (MP) technology based on an orthogonal circulant transform matrix (OCT). This combination can avoid the complicated adaptive bit loading or electronic equalization, making NOMA more attractive in a practical system.

Memorandum : feasibility assessment, bicycle or bicycle/pedestrian (multi-user) facility at Appomattox Court house NHP

DOT National Transportation Integrated Search

2007-10-12

This memorandum provides a preliminary feasibility assessment for a bicycle or combined bicycle/pedestrian (i.e., multi-user) facility at Appomattox Court House National Historical Park (NHP). This assessment is based on discussions with park staff, ...

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...

ISS Expedition 18 Multi-User Droplet Combustion Apparatus (MDCA) Chamber Insert Assembly (CIA) in Node 2

NASA Image and Video Library

2008-12-06

ISS018-E-010645 (6 Dec. 2008) --- Astronaut Michael Fincke, Expedition 18 commander, works on the Multi-User Droplet Combustion Apparatus (MDCA) Chamber Insert Assembly (CIA) in the Harmony node of the International Space Station.

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…

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…

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 required to go from selection to space flight.

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

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.

Genetic Local Search for Optimum Multiuser Detection Problem in DS-CDMA Systems

NASA Astrophysics Data System (ADS)

Wang, Shaowei; Ji, Xiaoyong

Optimum multiuser detection (OMD) in direct-sequence code-division multiple access (DS-CDMA) systems is an NP-complete problem. In this paper, we present a genetic local search algorithm, which consists of an evolution strategy framework and a local improvement procedure. The evolution strategy searches the space of feasible, locally optimal solutions only. A fast iterated local search algorithm, which employs the proprietary characteristics of the OMD problem, produces local optima with great efficiency. Computer simulations show the bit error rate (BER) performance of the GLS outperforms other multiuser detectors in all cases discussed. The computation time is polynomial complexity in the number of users.

Multi-User Droplet Combustion Apparatus (MDCA) Chamber Insert Assembly (CIA)

NASA Image and Video Library

2013-07-24

ISS036-E-024569 (24 July 2013) --- European Space Agency astronaut Luca Parmitano, Expedition 36 flight engineer, works on the Multi-User Droplet Combustion Apparatus (MDCA) Chamber Insert Assembly (CIA) at a maintenance work station in the Harmony node of the International Space Station.

Multi-User Droplet Combustion Apparatus (MDCA) Chamber Insert Assembly (CIA)

NASA Image and Video Library

2013-07-24

ISS036-E-024605 (24 July 2013) --- European Space Agency astronaut Luca Parmitano, Expedition 36 flight engineer, works on the Multi-User Droplet Combustion Apparatus (MDCA) Chamber Insert Assembly (CIA) at a maintenance work station in the Harmony node of the International Space Station.

Multi-User Droplet Combustion Apparatus (MDCA) Chamber Insert Assembly (CIA)

NASA Image and Video Library

2013-07-24

ISS036-E-024637 (24 July 2013) --- European Space Agency astronaut Luca Parmitano, Expedition 36 flight engineer, works on the Multi-User Droplet Combustion Apparatus (MDCA) Chamber Insert Assembly (CIA) at a maintenance work station in the Harmony node of the International Space Station.

Why the Disadvantaged Drop Out: The Administrators' View.

ERIC Educational Resources Information Center

Morrison, James L.; Ferrante, Reynolds

A report focusing on the academically disadvantaged minority group students is presented. Perceptions of administrators in public two-year colleges as to the major reasons for attrition of this group are examined. A pre-coded questionnaire was developed to gather information concerning programs of compensatory education in two-year colleges. It…

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.

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…

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…

Building Online Communities. Take Your Site beyond Content: Construct a Society on the Web.

ERIC Educational Resources Information Center

Glaser, Mark

1997-01-01

Discusses the establishment of online, or virtual, communities on the World Wide Web. Topics include corporate sites; community planning; virtual reality; games; America Online projects; MUDs (multiuser dungeons) and MOOs (multiuser object oriented); and a list of contacts for online community resources. (LRW)

A Multi-User Microcomputer System for Small Libraries.

ERIC Educational Resources Information Center

Leggate, Peter

1988-01-01

Describes the development of Bookshelf, a multi-user microcomputer system for small libraries that uses an integrated software package. The discussion covers the design parameters of the package, which were based on a survey of seven small libraries, and some characteristics of the software. (three notes with references) (CLB)

Global Village as Virtual Community (On Writing, Thinking, and Teacher Education).

ERIC Educational Resources Information Center

Polin, Linda

1993-01-01

Describes virtual communities known as Multi-User Simulated Environment (MUSE) or Multi-User Object Oriented environment (MOO), text-based computer "communities" whose inhabitants are a combination of the real people and constructed objects that people agree to treat as real. Describes their uses in the classroom. (SR)

Network coding multiuser scheme for indoor visible light communications

NASA Astrophysics Data System (ADS)

Zhang, Jiankun; Dang, Anhong

2017-12-01

Visible light communication (VLC) is a unique alternative for indoor data transfer and developing beyond point-to-point. However, for realizing high-capacity networks, VLC is facing challenges including the constrained bandwidth of the optical access point and random occlusion. A network coding scheme for VLC (NC-VLC) is proposed, with increased throughput and system robustness. Based on the Lambertian illumination model, theoretical decoding failure probability of the multiuser NC-VLC system is derived, and the impact of the system parameters on the performance is analyzed. Experiments demonstrate the proposed scheme successfully in the indoor multiuser scenario. These results indicate that the NC-VLC system shows a good performance under the link loss and random occlusion.

Performance of single-use and multiuse diamond rotary cutting instruments with turbine and electric handpieces.

PubMed

Rotella, Mario; Ercoli, Carlo; Funkenbusch, Paul D; Russell, Scott; Feng, Changyong

2014-01-01

As single-use rotary cutting instruments and electric handpieces become more available, the performance of these instruments with electric as compared to turbine handpieces requires evaluation. In addition, if rotary cutting instruments marketed as single-use instruments are used for multiple patients, the effects on their performance of cleaning, sterilization, and repeated use are of interest to the clinician. The purpose of the study was to evaluate how the cleaning, autoclaving, and repeated use of single-use and multiuse rotary cutting instruments, with either a turbine or electric handpiece, affected their performance. The effects on cutting performance of 2 handpieces (turbine and electric), 2 cleaning and sterilization conditions (cleaned and autoclaved versus noncleaned and nonautoclaved), and 6 different diamond rotary cutting instruments (4 single-use and 2 multiuse) during simulated tooth preparations were evaluated by using a 24-treatment condition full-factorial experimental design. A computer-controlled dedicated testing apparatus was used to simulate the cutting procedures, and machinable glass ceramic blocks were used as the cutting substrate for tangential cuts. In addition, for each treatment condition, 8 consecutive cuts, for a total of 192 cuts, were measured to assess the durability of the rotary cutting instruments. A linear mixed model was used to study the effect of instrument type, handpiece, cleaning, and sterilization, as well as the status and number of cuts on the outcome variables. The Tukey honestly significant difference test was used for the post hoc pairwise comparisons (α=.05). Performance, as measured by the rate of advancement, decreased with the repeated use of rotary cutting instruments (P<.001), while cleaning and sterilization procedures improved the average performance of the 8 cuts (P=.002). The electric handpiece showed a greater load than the turbine (P<.001) and a lower rate/load metric, but no differences in the rate of advancement. Significant differences were also detected among the different rotary cutting instruments tested with the Two Striper, which showed the highest cumulative performance of all groups. The repeated use of both single-use and multiuse rotary cutting instruments decreased cutting performance. The use of a cleaning and sterilization procedure between cuts improved the average cutting performance. During a tangential cutting process, although the ease of advancement (rate/load) was greater for the turbine, the electric handpiece did not produce a statistically different cutting rate. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

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…

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…

Addressing multi-use issues in sustainable forest management with signal-transfer modeling

Treesearch

Robert J. Luxmoore; William W. Hargrove; M. Lynn Tharp; W. Mac Post; Michael W. Berry; Karen S. Minser; Wendell P. Cropper; Dale W. Johnson; Boris Zeide; Ralph L. Amateis; Harold E. Burkhart; V. Clark Baldwin; Kelly D. Peterson

2002-01-01

Management decisions concerning impacts of projected changes in environmental and social conditions on multi-use forest products and services, such as productivity, water supply or carbon sequestration, may be facilitated with signal-transfer modeling. This simulation method utilizes a hierarchy of simulators in which the integrated responses (signals) from smaller-...

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…

Wireless Computing Architecture III

DTIC Science & Technology

2013-09-01

MIMO Multiple-Input and Multiple-Output MIMO /CON MIMO with concurrent hannel access and estimation MU- MIMO Multiuser MIMO OFDM Orthogonal...compressive sensing \\; a design for concurrent channel estimation in scalable multiuser MIMO networking; and novel networking protocols based on machine...Network, Antenna Arrays, UAV networking, Angle of Arrival, Localization MIMO , Access Point, Channel State Information, Compressive Sensing 16

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…

Preservice Teachers Experience Reading Response Pedagogy in a Multi-User Virtual Environment

ERIC Educational Resources Information Center

Dooley, Caitlin McMunn; Calandra, Brendan; Harmon, Stephen

2014-01-01

This qualitative case study describes how 18 preservice teachers learned to nurture literary meaning-making via activities based on Louise Rosenblatt's Reader Response Theory within a multi-user virtual environment (MUVE). Participants re-created and responded to scenes from selected works of children's literature in Second Life as a way to…

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.

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.

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

2016-07-08

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.

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…

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…

Hybrid Augmented Reality for Participatory Learning: The Hidden Efficacy of Multi-User Game-Based Simulation

ERIC Educational Resources Information Center

Oh, Seungjae; So, Hyo-Jeong; Gaydos, Matthew

2018-01-01

The goal for this research is to articulate and test a new hybrid Augmented Reality (AR) environment for conceptual understanding. From the theoretical lens of embodied interaction, we have designed a multi-user participatory simulation called ARfract where visitors in a science museum can learn about complex scientific concepts on the refraction…

Exploring the Integration of Technology into Jewish Education: Multi-User Virtual Environments and Supplementary School Settings

ERIC Educational Resources Information Center

Sohn, Johannah Eve

2014-01-01

This descriptive case study explores the implementation of a multi-user virtual environment (MUVE) in a Jewish supplemental school setting. The research was conducted to present the recollections and reflections of three constituent populations of a new technology exploring constructivist education in the context of supplemental and online…

Characterizing Student Navigation in Educational Multiuser Virtual Environments: A Case Study Using Data from the River City Project

ERIC Educational Resources Information Center

Dukas, Georg

2009-01-01

Though research in emerging technologies is vital to fulfilling their incredible potential for educational applications, it is often fraught with analytic challenges related to large datasets. This thesis explores these challenges in researching multiuser virtual environments (MUVEs). In a MUVE, users assume a persona and traverse a virtual space…

Managing Cognitive Load in Educational Multi-User Virtual Environments: Reflection on Design Practice

ERIC Educational Resources Information Center

Nelson, Brian C.; Erlandson, Benjamin E.

2008-01-01

In this paper, we explore how the application of multimedia design principles may inform the development of educational multi-user virtual environments (MUVEs). We look at design principles that have been shown to help learners manage cognitive load within multimedia environments and conduct a conjectural analysis of the extent to which such…

Theoretical Limits on Multiuser Molecular Communication in Internet of Nano-Bio Things.

PubMed

Dinc, Ergin; Akan, Ozgur B

2017-06-01

In nano-bio networks, multiple transmitter-receiver pairs will operate in the same medium. Both inter-symbol interference and multi-user interference can cause saturation at the receiver side, and this effect may cause an outage. Thus, we propose a tractable framework to calculate the theoretical operating points for fully absorbing receiver.

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"…

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.…

Multiuser TOA Estimation Algorithm in DS-CDMA Sparse Channel for Radiolocation

NASA Astrophysics Data System (ADS)

Kim, Sunwoo

This letter considers multiuser time delay estimation in a sparse channel environment for radiolocation. The generalized successive interference cancellation (GSIC) algorithm is used to eliminate the multiple access interference (MAI). To adapt GSIC to sparse channels the alternating maximization (AM) algorithm is considered, and the continuous time delay of each path is estimated without requiring a priori known data sequences.

The Impact of Student Self-Efficacy on Scientific Inquiry Skills: An Exploratory Investigation in "River City," a Multi-User Virtual Environment

ERIC Educational Resources Information Center

Ketelhut, Diane Jass

2007-01-01

This exploratory study investigated data-gathering behaviors exhibited by 100 seventh-grade students as they participated in a scientific inquiry-based curriculum project delivered by a multi-user virtual environment (MUVE). This research examined the relationship between students' self-efficacy on entry into the authentic scientific activity and…

Exploring the Educational Potential of Three-Dimensional Multi-User Virtual Worlds for STEM Education: A Mixed-Method Systematic Literature Review

ERIC Educational Resources Information Center

Pellas, Nikolaos; Kazanidis, Ioannis; Konstantinou, Nikolaos; Georgiou, Georgia

2017-01-01

The present literature review builds on the results of 50 research articles published from 2000 until 2016. All these studies have successfully accomplished various learning tasks in the domain of Science, Technology, Engineering, and Mathematics (STEM) education using three-dimensional (3-D) multi-user virtual worlds for Primary, Secondary and…

Multi-User Domain Object Oriented (MOO) as a High School Procedure for Foreign Language Acquisition.

ERIC Educational Resources Information Center

Backer, James A.

Foreign language students experience added difficulty when they are isolated from native speakers and from the culture of the target language. It has been posited that MOO (Multi-User Domain Object Oriented) may help overcome the geographical isolation of these students. MOOs are Internet-based virtual worlds in which people from all over the real…

Uplink transmit beamforming design for SINR maximization with full multiuser channel state information

NASA Astrophysics Data System (ADS)

Xi, Songnan; Zoltowski, Michael D.

2008-04-01

Multiuser multiple-input multiple-output (MIMO) systems are considered in this paper. We continue our research on uplink transmit beamforming design for multiple users under the assumption that the full multiuser channel state information, which is the collection of the channel state information between each of the users and the base station, is known not only to the receiver but also to all the transmitters. We propose an algorithm for designing optimal beamforming weights in terms of maximizing the signal-to-interference-plus-noise ratio (SINR). Through statistical modeling, we decouple the original mathematically intractable optimization problem and achieved a closed-form solution. As in our previous work, the minimum mean-squared error (MMSE) receiver with successive interference cancellation (SIC) is adopted for multiuser detection. The proposed scheme is compared with an existing jointly optimized transceiver design, referred to as the joint transceiver in this paper, and our previously proposed eigen-beamforming algorithm. Simulation results demonstrate that our algorithm, with much less computational burden, accomplishes almost the same performance as the joint transceiver for spatially independent MIMO channel and even better performance for spatially correlated MIMO channels. And it always works better than our previously proposed eigen beamforming algorithm.

Research on multi-user encrypted search scheme in cloud environment

NASA Astrophysics Data System (ADS)

Yu, Zonghua; Lin, Sui

2017-05-01

Aiming at the existing problems of multi-user encrypted search scheme in cloud computing environment, a basic multi-user encrypted scheme is proposed firstly, and then the basic scheme is extended to an anonymous hierarchical management authority. Compared with most of the existing schemes, the scheme not only to achieve the protection of keyword information, but also to achieve the protection of user identity privacy; the same time, data owners can directly control the user query permissions, rather than the cloud server. In addition, through the use of a special query key generation rules, to achieve the hierarchical management of the user's query permissions. The safety analysis shows that the scheme is safe and that the performance analysis and experimental data show that the scheme is practicable.

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

2007-02-01

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.

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.

MDCA (Multi-user Drop Combustion Apparatus) operations

NASA Image and Video Library

2009-05-12

ISS019-E-015912 (12 May 2009) --- Japan Aerospace Exploration Agency (JAXA) astronaut Koichi Wakata, Expedition 19/20 flight engineer, works on the Combustion Integrated Rack (CIR) Multi-user Drop Combustion Apparatus (MDCA) in the Destiny laboratory of the International Space Station. Wakata removed and replaced one fuel reservoir, which required temporary opening the front end cap and removing the fuel supply bypass Quick Disconnect (QD).

MDCA (Multi-user Drop Combustion Apparatus) operations

NASA Image and Video Library

2009-05-12

ISS019-E-015906 (12 May 2009) --- Japan Aerospace Exploration Agency (JAXA) astronaut Koichi Wakata, Expedition 19/20 flight engineer, works on the Combustion Integrated Rack (CIR) Multi-user Drop Combustion Apparatus (MDCA) in the Destiny laboratory of the International Space Station. Wakata removed and replaced one fuel reservoir, which required temporary opening the front end cap and removing the fuel supply bypass Quick Disconnect (QD).

MDCA (Multi-user Drop Combustion Apparatus) operations

NASA Image and Video Library

2009-05-12

ISS019-E-015910(12 May 2009) --- Japan Aerospace Exploration Agency (JAXA) astronaut Koichi Wakata, Expedition 19/20 flight engineer, works on the Combustion Integrated Rack (CIR) Multi-user Drop Combustion Apparatus (MDCA) in the Destiny laboratory of the International Space Station. Wakata removed and replaced one fuel reservoir, which required temporary opening the front end cap and removing the fuel supply bypass Quick Disconnect (QD).

War Gamers Handbook: A Guide for Professional War Gamers

DTIC Science & Technology

2015-11-01

more complex games led us to integrate knowledge management, web tools, and multitouch , multiuser technologies in order to more efficiently and... Multitouch multiuser (MTMU) and communications operating picture (COP) interfaces ◊ Web development—Web tools and player interfaces Now that the game...hurricane or flood scenario to provide a plausible backdrop to facilitate player interaction toward game objectives. Scenarios should include only the

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…

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.

Average Likelihood Methods for Code Division Multiple Access (CDMA)

DTIC Science & Technology

2014-05-01

lengths in the range of 22 to 213 and possibly higher. Keywords: DS / CDMA signals, classification, balanced CDMA load, synchronous CDMA , decision...likelihood ratio test (ALRT). We begin this classification problem by finding the size of the spreading matrix that generated the DS - CDMA signal. As...Theoretical Background The classification of DS / CDMA signals should not be confused with the problem of multiuser detection. The multiuser detection deals

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…

Smart LED allocation scheme for efficient multiuser visible light communication networks.

PubMed

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

2015-05-18

In a multiuser bidirectional visible light communication (VLC), a large number of LEDs or an LED array needs to be allocated in an efficient manner to ensure sustainable data rate and link quality. Moreover, in order to support an increasing or decreasing number of users in the network, the LED allocation is required to be performed dynamically. In this paper, a novel smart LED allocation scheme for efficient multiuser VLC networks is presented. The proposed scheme allocates RGB LEDs to multiple users in a dynamic and efficient fashion, while satisfying illumination requirements in an indoor environment. The smart LED array comprised of RGB LEDs is divided into sectors according to the location of the users. The allocated sectors then provide optical power concentration toward the users for efficient and reliable data transmission. An algorithm for the dynamic allocation of the LEDs is also presented. To verify its effective resource allocation feature of the proposed scheme, simulations were performed. It is found that the proposed smart LED allocation scheme provides the effect of optical beamforming toward individual users, thereby increasing the collective power concentration of the optical signals on the desirable users and resulting in significantly increased data rate, while ensuring sufficient illumination in a multiuser VLC environment.

A Multiuser Detector Based on Artificial Bee Colony Algorithm for DS-UWB Systems

PubMed Central

Liu, Xiaohui

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

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.

A physician-led initiative to improve clinical documentation results in improved health care documentation, case mix index, and increased contribution margin.

PubMed

Aiello, Francesco A; Judelson, Dejah R; Durgin, Jonathan M; Doucet, Danielle R; Simons, Jessica P; Durocher, Dawn M; Flahive, Julie M; Schanzer, Andres

2018-05-04

Clinical documentation is the key determinant of inpatient acuity of illness and payer reimbursement. Every inpatient hospitalization is placed into a diagnosis related group with a relative value based on documented procedures, conditions, comorbidities and complications. The Case Mix Index (CMI) is an average of these diagnosis related groups and directly impacts physician profiling, medical center profiling, reimbursement, and quality reporting. We hypothesize that a focused, physician-led initiative to improve clinical documentation of vascular surgery inpatients results in increased CMI and contribution margin. A physician-led coding initiative to educate physicians on the documentation of comorbidities and conditions was initiated with concurrent chart review sessions with coding specialists for 3 months, and then as needed, after the creation of a vascular surgery documentation guide. Clinical documentation and billing for all carotid endarterectomy (CEA) and open infrainguinal procedures (OIPs) performed between January 2013 and July 2016 were stratified into precoding and postcoding initiative groups. Age, duration of stay, direct costs, actual reimbursements, contribution margin (CM), CMI, rate of complication or comorbidity, major complication or comorbidity, severity of illness, and risk of mortality assigned to each discharge were abstracted. Data were compared over time by standardizing Centers for Medicare and Medicaid Services (CMS) values for each diagnosis related group and using a CMS base rate reimbursement. Among 458 CEA admissions, postcoding initiative CEA patients (n = 253) had a significantly higher CMI (1.36 vs 1.25; P = .03), CM ($7859 vs $6650; P = .048), and CMS base rate reimbursement ($8955 vs $8258; P = .03) than precoding initiative CEA patients (n = 205). The proportion of admissions with a documented major complication or comorbidity and complication or comorbidity was significantly higher after the coding initiative (43% vs 27%; P < .01). Among 504 OIPs, postcoding initiative patients (n = 227) had a significantly higher CMI (2.23 vs 2.05; P < .01), actual reimbursement ($23,203 vs $19,909; P < .01), CM ($12,165 vs $8840; P < .01), and CMS base rate reimbursement ($14,649 vs $13,496; P < .01) than precoding initiative patients (n = 277). The proportion of admissions with a documented major complication or comorbidity and complication or comorbidity was significantly higher after the coding initiative (61% vs 43%; P < .01). For both CEA and OIPs, there were no differences in age, duration of stay, total direct costs, or primary insurance status between the precoding and postcoding patient groups. Accurate and detailed clinical documentation is required for key stakeholders to characterize the acuity of inpatient admissions and ensure appropriate reimbursement; it is also a key component of risk-adjustment methods for assessing quality of care. A physician-led documentation initiative significantly increased CMI and CM. Copyright © 2018 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

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

A Robotic Coach Architecture for Elder Care (ROCARE) Based on Multi-user Engagement Models

PubMed Central

Fan, Jing; Bian, Dayi; Zheng, Zhi; Beuscher, Linda; Newhouse, Paul A.; Mion, Lorraine C.; Sarkar, Nilanjan

2017-01-01

The aging population with its concomitant medical conditions, physical and cognitive impairments, at a time of strained resources, establishes the urgent need to explore advanced technologies that may enhance function and quality of life. Recently, robotic technology, especially socially assistive robotics has been investigated to address the physical, cognitive, and social needs of older adults. Most system to date have predominantly focused on one-on-one human robot interaction (HRI). In this paper, we present a multi-user engagement-based robotic coach system architecture (ROCARE). ROCARE is capable of administering both one-on-one and multi-user HRI, providing implicit and explicit channels of communication, and individualized activity management for long-term engagement. Two preliminary feasibility studies, a one-on-one interaction and a triadic interaction with two humans and a robot, were conducted and the results indicated potential usefulness and acceptance by older adults, with and without cognitive impairment. PMID:28113672

Experimental demonstration of multiuser communication in deep water using time reversal.

PubMed

Shimura, T; Ochi, H; Song, H C

2013-10-01

Multiuser communication is demonstrated using experimental data (450-550 Hz) collected in deep water, south of Japan. The multiple users are spatially distributed either in depth or range while a 114-m long, 20-element vertical array (i.e., base station) is deployed to around the sound channel axis (~1000 m). First, signals received separately from ranges of 150 km and 180 km at various depths are combined asynchronously to generate multiuser communication sequences for subsequent processing, achieving an aggregate data rate of 300 bits/s for up to three users. Adaptive time reversal is employed to separate collided packets at the base station, followed by a single channel decision feedback equalizer. Then it is demonstrated that two users separated by 3 km in range at ~1000 m depth can transmit information simultaneously to the base station at ~500 km range with an aggregate data rate of 200 bits/s.

Automatic Bluetooth testing for mobile multi-user applications

NASA Astrophysics Data System (ADS)

Luck, Dennis; Hörning, Henrik; Edlich, Stefan

2008-02-01

In this paper we present a simple approach for the development of multiuser and multimedia applications based on Bluetooth. One main obstacle for Bluetooth synchronization of mobile applications is the lack of a complete specification implementation. Nowadays these applications must be on market as fast as possible. Hence, developers must be able to test several dozens of mobile devices for their Bluetooth capability. And surprisingly, the capabilities differ not only between the Bluetooth specification 1.0 and 2.0. The current development was triggered by the development of mass applications as mobile multiuser games (e.g. Tetris). Our Application can be distributed on several mobile phones. If started, the Bluetooth applications try to connect each other and automatically start to detect device capabilities. These capabilities will be gathered and distributed to a server. The server performs statistical investigations and aggregates them to be presented as a report. The result is a faster development regarding mobile communications.

Privacy and Security in Multi-User Health Kiosks

PubMed Central

TAKYI, HAROLD; WATZLAF, VALERIE; MATTHEWS, JUDITH TABOLT; ZHOU, LEMING; DEALMEIDA, DILHARI

2017-01-01

Enforcement of the Health Insurance Portability and Accountability Act (HIPAA) and the Health Information Technology for Economic and Clinical Health Act (HITECH) has gotten stricter and penalties have become more severe in response to a significant increase in computer-related information breaches in recent years. With health information said to be worth twice as much as other forms of information on the underground market, making preservation of privacy and security an integral part of health technology development, rather than an afterthought, not only mitigates risks but also helps to ensure HIPAA and HITECH compliance. This paper provides a guide, based on the Office for Civil Rights (OCR) audit protocol, for creating and maintaining an audit checklist for multi-user health kiosks. Implementation of selected audit elements for a multi-user health kiosk designed for use by community-residing older adults illustrates how the guide can be applied. PMID:28814990

A Robotic Coach Architecture for Elder Care (ROCARE) Based on Multi-User Engagement Models.

PubMed

Fan, Jing; Bian, Dayi; Zheng, Zhi; Beuscher, Linda; Newhouse, Paul A; Mion, Lorraine C; Sarkar, Nilanjan

2017-08-01

The aging population with its concomitant medical conditions, physical and cognitive impairments, at a time of strained resources, establishes the urgent need to explore advanced technologies that may enhance function and quality of life. Recently, robotic technology, especially socially assistive robotics has been investigated to address the physical, cognitive, and social needs of older adults. Most system to date have predominantly focused on one-on-one human robot interaction (HRI). In this paper, we present a multi-user engagement-based robotic coach system architecture (ROCARE). ROCARE is capable of administering both one-on-one and multi-user HRI, providing implicit and explicit channels of communication, and individualized activity management for long-term engagement. Two preliminary feasibility studies, a one-on-one interaction and a triadic interaction with two humans and a robot, were conducted and the results indicated potential usefulness and acceptance by older adults, with and without cognitive impairment.

Parallel computation in a three-dimensional elastic-plastic finite-element analysis

NASA Technical Reports Server (NTRS)

Shivakumar, K. N.; Bigelow, C. A.; Newman, J. C., Jr.

1992-01-01

A CRAY parallel processing technique called autotasking was implemented in a three-dimensional elasto-plastic finite-element code. The technique was evaluated on two CRAY supercomputers, a CRAY 2 and a CRAY Y-MP. Autotasking was implemented in all major portions of the code, except the matrix equations solver. Compiler directives alone were not able to properly multitask the code; user-inserted directives were required to achieve better performance. It was noted that the connect time, rather than wall-clock time, was more appropriate to determine speedup in multiuser environments. For a typical example problem, a speedup of 2.1 (1.8 when the solution time was included) was achieved in a dedicated environment and 1.7 (1.6 with solution time) in a multiuser environment on a four-processor CRAY 2 supercomputer. The speedup on a three-processor CRAY Y-MP was about 2.4 (2.0 with solution time) in a multiuser environment.

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.

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.

Secure Communications in CIoT Networks with a Wireless Energy Harvesting Untrusted Relay

PubMed Central

Hu, Hequn; Liao, Xuewen

2017-01-01

The Internet of Things (IoT) represents a bright prospect that a variety of common appliances can connect to one another, as well as with the rest of the Internet, to vastly improve our lives. Unique communication and security challenges have been brought out by the limited hardware, low-complexity, and severe energy constraints of IoT devices. In addition, a severe spectrum scarcity problem has also been stimulated by the use of a large number of IoT devices. In this paper, cognitive IoT (CIoT) is considered where an IoT network works as the secondary system using underlay spectrum sharing. A wireless energy harvesting (EH) node is used as a relay to improve the coverage of an IoT device. However, the relay could be a potential eavesdropper to intercept the IoT device’s messages. This paper considers the problem of secure communication between the IoT device (e.g., sensor) and a destination (e.g., controller) via the wireless EH untrusted relay. Since the destination can be equipped with adequate energy supply, secure schemes based on destination-aided jamming are proposed based on power splitting (PS) and time splitting (TS) policies, called intuitive secure schemes based on PS (Int-PS), precoded secure scheme based on PS (Pre-PS), intuitive secure scheme based on TS (Int-TS) and precoded secure scheme based on TS (Pre-TS), respectively. The secure performances of the proposed schemes are evaluated through the metric of probability of successfully secure transmission (PSST), which represents the probability that the interference constraint of the primary user is satisfied and the secrecy rate is positive. PSST is analyzed for the proposed secure schemes, and the closed form expressions of PSST for Pre-PS and Pre-TS are derived and validated through simulation results. Numerical results show that the precoded secure schemes have better PSST than the intuitive secure schemes under similar power consumption. When the secure schemes based on PS and TS polices have similar PSST, the average transmit power consumption of the secure scheme based on TS is lower. The influences of power splitting and time slitting ratios are also discussed through simulations. PMID:28869540

Dietary arginine and linear growth: the Copenhagen School Child Intervention Study.

PubMed

van Vught, Anneke J A H; Dagnelie, Pieter C; Arts, Ilja C W; Froberg, Karsten; Andersen, Lars B; El-Naaman, Bianca; Bugge, Anna; Nielsen, Birgit M; Heitman, Berit L

2013-03-28

The amino acid arginine is a well-known growth hormone (GH) stimulator and GH is an important modulator of linear growth. The aim of the present study was to investigate the effect of dietary arginine on growth velocity in children between 7 and 13 years of age. Data from the Copenhagen School Child Intervention Study during 2001-2 (baseline), and at 3-year and 7-year follow-up, were used. Arginine intake was estimated via a 7 d precoded food diary at baseline and 3-year follow-up. Data were analysed in a multilevel structure in which children were embedded within schools. Random intercept and slopes were defined to estimate the association between arginine intake and growth velocity, including the following covariates: sex; age; baseline height; energy intake; puberty stage at 7-year follow-up and intervention/control group. The association between arginine intake and growth velocity was significant for the third and fourth quintile of arginine intake (2.5-2.8 and 2.8-3.2 g/d, respectively) compared with the first quintile ( < 2.2 g/d) (P for trend = 0.04). Protein intake (excluding arginine) was significantly associated with growth velocity; however, the association was weaker than the association between arginine intake and growth velocity (P for trend = 0.14). The results of the present study suggest a dose-dependent physiological role of habitual protein intake, and specifically arginine intake, on linear growth in normally growing children. However, since the study was designed in healthy children, we cannot firmly conclude whether arginine supplementation represents a relevant clinical strategy. Further research is needed to investigate whether dietary arginine may represent a nutritional strategy potentially advantageous for the prevention and treatment of short stature.

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"…

Cabana Multi-User Spaceport Tour of KSC

NASA Image and Video Library

2017-02-17

Kennedy Space Center Director Bob Cabana speaks to members of the news media on the balcony of Operations Support Building II describing the site's transition from a primarily government-only facility to a premier, multi-user spaceport. In the background is the Vehicle Assembly Building (VAB). Modifications were recently completed in the VAB where new work platforms were installed to support processing of NASA's Space Launch System rocket designed to send the Orion spacecraft on missions beyond low-Earth orbit.

Alteration and Implementation of the CP/M-86 Operating System for a Multi-User Environment.

DTIC Science & Technology

1982-12-01

THE CP/M-86 OPERATING SYSTEM FOR A MULTI-USER ENVIRONMENT by Thomas V. Almquist and David S. Stevens C-, December 1982 ,LU Thesis Advisor : U. R. Kodres...tool$ 044, robo O0eA 6^900091 Approved for public release; distribution unlimited Alteration and Implementation of the CP/M-86 Operating System for a...SCIENCE IN COMPUTER SCIENCE from the NAVAL POSTGRADUATE SCHOOL December 1982 Authors: Approved by: ..... .. . . . . . . . . Thesis Advisor Second

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 relevance to the current commercial space industry, and the challenges that continue to drive improvement with a focus on areas of safety management and risk assessment that have been crucial in KSC's evolution into a multi-user spaceport. These solutions may be useful to government entities and private companies looking to partner with the commercial space industry.

Exploring the Plausibility of a National Multi-Agency Communications System for the Homeland Security Community: A Southeast Ohio Half-Duplex Voice Over IP Case Study

DTIC Science & Technology

2009-03-01

modeled after the use by computer gamers in MMORPGs (massively multiuser online role-playing games). This is a good example of engaging the larger...during grant evaluations. There are more and more peer reviewed journal articles being written on MMORPGs , but this work is mainly geared towards...of the massively multiuser online role-playing games ( MMORPGs ). Most of the literature is about leadership and social networking. There is

Performance of Improved Channel Allocation for Multicarrier CDMA with Adaptive Frequency Hopping and Multiuser Detection

DTIC Science & Technology

2008-08-29

resulting in much larger system capacity than for a non-adaptive MC direct-sequence ( DS )- CDMA system. This conclusion is confirmed for realistic fading...system capacity than for a non-adaptive MC direct-sequence ( DS )- CDMA system. This conclusion is confirmed for realistic fading channels with correlated...transmission method exploits both frequency and multiuser diversity and improves on non-adaptive MC DS - CDMA sys- tems in [6]. In this paper, we focus on the

Cabana Multi-User Spaceport Tour of KSC

NASA Image and Video Library

2017-02-17

Nancy Bray, director of Spaceport Integration and Services at NASA's Kennedy Space Center, speaks to members of the news media on the balcony of Operations Support Building II describing the site's transition from a primarily government-only facility to a premier, multi-user spaceport. In the background is the Vehicle Assembly Building (VAB). Modifications were recently completed in the VAB where new work platforms were installed to support processing of NASA's Space Launch System rocket designed to send the Orion spacecraft on missions beyond low-Earth orbit.

Cabana Multi-User Spaceport Tour of KSC

NASA Image and Video Library

2017-02-17

Tom Engler, director of Center Planning and Development at NASA's Kennedy Space Center, speaks to members of the news media on the balcony of Operations Support Building II describing the site's transition from a primarily government-only facility to a premier, multi-user spaceport. In the background is the Vehicle Assembly Building (VAB). Modifications were recently completed in the VAB where new work platforms were installed to support processing of NASA's Space Launch System rocket designed to send the Orion spacecraft on missions beyond low-Earth orbit.

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.

Single-Trial Classification of Multi-User P300-Based Brain-Computer Interface Using Riemannian Geometry.

PubMed

Korczowski, L; Congedo, M; Jutten, C

2015-08-01

The classification of electroencephalographic (EEG) data recorded from multiple users simultaneously is an important challenge in the field of Brain-Computer Interface (BCI). In this paper we compare different approaches for classification of single-trials Event-Related Potential (ERP) on two subjects playing a collaborative BCI game. The minimum distance to mean (MDM) classifier in a Riemannian framework is extended to use the diversity of the inter-subjects spatio-temporal statistics (MDM-hyper) or to merge multiple classifiers (MDM-multi). We show that both these classifiers outperform significantly the mean performance of the two users and analogous classifiers based on the step-wise linear discriminant analysis. More importantly, the MDM-multi outperforms the performance of the best player within the pair.

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.

An FPGA-based DS-CDMA multiuser demodulator employing adaptive multistage parallel interference cancellation

NASA Astrophysics Data System (ADS)

Li, Xinhua; Song, Zhenyu; Zhan, Yongjie; Wu, Qiongzhi

2009-12-01

Since the system capacity is severely limited, reducing the multiple access interfere (MAI) is necessary in the multiuser direct-sequence code division multiple access (DS-CDMA) system which is used in the telecommunication terminals data-transferred link system. In this paper, we adopt an adaptive multistage parallel interference cancellation structure in the demodulator based on the least mean square (LMS) algorithm to eliminate the MAI on the basis of overviewing various of multiuser dectection schemes. Neither a training sequence nor a pilot signal is needed in the proposed scheme, and its implementation complexity can be greatly reduced by a LMS approximate algorithm. The algorithm and its FPGA implementation is then derived. Simulation results of the proposed adaptive PIC can outperform some of the existing interference cancellation methods in AWGN channels. The hardware setup of mutiuser demodulator is described, and the experimental results based on it demonstrate that the simulation results shows large performance gains over the conventional single-user demodulator.

Stakeholders Opinions on Multi-Use Deep Water Offshore Platform in Hsiao-Liu-Chiu, Taiwan

PubMed Central

Sie, Ya-Tsune; Chang, Yang-Chi; Lu, Shiau-Yun

2018-01-01

This paper describes a group model building activity designed to elicit the potential effects a projected multi-use deep water offshore platform may have on its local environment, including ecological and socio-economic issues. As such a platform is proposed for construction around the island of Hsiao-Liu-Chiu, Taiwan, we organized several meetings with the local stakeholders and structured the debates using group modeling methods to promote consensus. During the process, the participants iteratively built and revised a causal-loop diagram that summarizes their opinions. Overall, local stakeholders concluded that a multi-use deep water offshore marine platform might have beneficial effects for Hsiao-Liu-Chiu because more tourists and fish could be attracted by the structure, but they also raised some potential problems regarding the law in Taiwan and the design of the offshore platform, especially its resistance to extreme weather. We report the method used and the main results and insights gained during the process. PMID:29415521

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

First demonstration and field trial on multi-user UDWDM-PON full duplex PSK-PSK with single monolithic integrated dual-output-DFB-SOA based ONUs.

PubMed

Chu, GuangYong; Maho, Anaëlle; Cano, Iván; Polo, Victor; Brenot, Romain; Debrégeas, Hélène; Prat, Josep

2016-10-15

We demonstrate a monolithically integrated dual-output DFB-SOA, and conduct the field trial on a multi-user bidirectional coherent ultradense wavelength division multiplexing-passive optical network (UDWDM-PON). To the best of our knowledge, this is the first achievement of simplified single integrated laser-based neighboring coherent optical network units (ONUs) with a 12.5 GHz channel spaced ultra-dense access network, including both downstream and upstream, taking the benefits of low footprint and low-temperature dependence.

Multi-pulse frequency shifted (MPFS) multiple access modulation for ultra wideband

DOEpatents

Nekoogar, Faranak [San Ramon, CA; Dowla, Farid U [Castro Valley, CA

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.

Secure Communications in CIoT Networks with a Wireless Energy Harvesting Untrusted Relay.

PubMed

Hu, Hequn; Gao, Zhenzhen; Liao, Xuewen; Leung, Victor C M

2017-09-04

The Internet of Things (IoT) represents a bright prospect that a variety of common appliances can connect to one another, as well as with the rest of the Internet, to vastly improve our lives. Unique communication and security challenges have been brought out by the limited hardware, low-complexity, and severe energy constraints of IoT devices. In addition, a severe spectrum scarcity problem has also been stimulated by the use of a large number of IoT devices. In this paper, cognitive IoT (CIoT) is considered where an IoT network works as the secondary system using underlay spectrum sharing. A wireless energy harvesting (EH) node is used as a relay to improve the coverage of an IoT device. However, the relay could be a potential eavesdropper to intercept the IoT device's messages. This paper considers the problem of secure communication between the IoT device (e.g., sensor) and a destination (e.g., controller) via the wireless EH untrusted relay. Since the destination can be equipped with adequate energy supply, secure schemes based on destination-aided jamming are proposed based on power splitting (PS) and time splitting (TS) policies, called intuitive secure schemes based on PS (Int-PS), precoded secure scheme based on PS (Pre-PS), intuitive secure scheme based on TS (Int-TS) and precoded secure scheme based on TS (Pre-TS), respectively. The secure performances of the proposed schemes are evaluated through the metric of probability of successfully secure transmission ( P S S T ), which represents the probability that the interference constraint of the primary user is satisfied and the secrecy rate is positive. P S S T is analyzed for the proposed secure schemes, and the closed form expressions of P S S T for Pre-PS and Pre-TS are derived and validated through simulation results. Numerical results show that the precoded secure schemes have better P S S T than the intuitive secure schemes under similar power consumption. When the secure schemes based on PS and TS polices have similar P S S T , the average transmit power consumption of the secure scheme based on TS is lower. The influences of power splitting and time slitting ratios are also discussed through simulations.

Real-Time Distributed Implementation of Interference Alignment with Analog Feedback

DTIC Science & Technology

2013-01-01

manner as in Figure 5(a). As such, six OFDM symbols are transmitted for our three user 2 × 2 MIMO system. The training does not experience precoding nor...pp. 159170, August 2009. [12] O. E. Ayach, S.W. Peters, and R.W. Heath Jr., ”The feasibility of interference alignment over measured MIMO - OFDM ...A Space-Time Receiver with Joint Synchronization and Interference Cancellation in Asynchronous MIMO - OFDM Systems,” IEEE Transactions on Vehicular

MEMS For Rolling-Element Bearings

DTIC Science & Technology

2010-01-01

Layers Illustration (not to scale) 17 - 4PH Stainless Steel Cross-section from A-A’ Top view from B-B’ Au flash ~ 500 Å Ni ~ 25 µm B...B’ A A’ 17 - 4PH Stainless Steel Pre-metallization region Pre-metallization of steel substrate for bonding of MEMS strain sensor Figure RB6: Pre...Code: RES-04 Canton, OH 44706 - REPORT DOCUMENTATION PAGE b. ABSTRACT UU c. THIS PAGE UU 2. REPORT TYPE Final Report 17 . LIMITATION OF ABSTRACT UU

Accumulate-Repeat-Accumulate-Accumulate-Codes

NASA Technical Reports Server (NTRS)

Divsalar, Dariush; Dolinar, Sam; Thorpe, Jeremy

2004-01-01

Inspired by recently proposed Accumulate-Repeat-Accumulate (ARA) codes [15], in this paper we propose a channel coding scheme called Accumulate-Repeat-Accumulate-Accumulate (ARAA) codes. These codes can be seen as serial turbo-like codes or as a subclass of Low Density Parity Check (LDPC) codes, and they have a projected graph or protograph representation; this allows for a high-speed iterative decoder implementation using belief propagation. An ARAA code can be viewed as a precoded Repeat-and-Accumulate (RA) code with puncturing in concatenation with another accumulator, where simply an accumulator is chosen as the precoder; thus ARAA codes have a very fast encoder structure. Using density evolution on their associated protographs, we find examples of rate-lJ2 ARAA codes with maximum variable node degree 4 for which a minimum bit-SNR as low as 0.21 dB from the channel capacity limit can be achieved as the block size goes to infinity. Such a low threshold cannot be achieved by RA or Irregular RA (IRA) or unstructured irregular LDPC codes with the same constraint on the maximum variable node degree. Furthermore by puncturing the accumulators we can construct families of higher rate ARAA codes with thresholds that stay close to their respective channel capacity thresholds uniformly. Iterative decoding simulation results show comparable performance with the best-known LDPC codes but with very low error floor even at moderate block sizes.

Efficient multitasking of Choleski matrix factorization on CRAY supercomputers

NASA Technical Reports Server (NTRS)

Overman, Andrea L.; Poole, Eugene L.

1991-01-01

A Choleski method is described and used to solve linear systems of equations that arise in large scale structural analysis. The method uses a novel variable-band storage scheme and is structured to exploit fast local memory caches while minimizing data access delays between main memory and vector registers. Several parallel implementations of this method are described for the CRAY-2 and CRAY Y-MP computers demonstrating the use of microtasking and autotasking directives. A portable parallel language, FORCE, is used for comparison with the microtasked and autotasked implementations. Results are presented comparing the matrix factorization times for three representative structural analysis problems from runs made in both dedicated and multi-user modes on both computers. CPU and wall clock timings are given for the parallel implementations and are compared to single processor timings of the same algorithm.

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.

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.

A software for managing chemical processes in a multi-user laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Camino, Fernando E.

Here, we report a software for logging chemical processes in a multi-user laboratory, which implements a work flow designed to reduce hazardous situations associated with the disposal of chemicals in incompatible waste containers. The software allows users to perform only those processes displayed in their list of authorized chemical processes and provides the location and label code of waste containers, among other useful information. The software has been used for six years in the cleanroom of the Center for Functional Nanomaterials at Brookhaven National Laboratory and has been an important factor for the excellent safety record of the Center.

Support vector machine multiuser receiver for DS-CDMA signals in multipath channels.

PubMed

Chen, S; Samingan, A K; Hanzo, L

2001-01-01

The problem of constructing an adaptive multiuser detector (MUD) is considered for direct sequence code division multiple access (DS-CDMA) signals transmitted through multipath channels. The emerging learning technique, called support vector machines (SVM), is proposed as a method of obtaining a nonlinear MUD from a relatively small training data block. Computer simulation is used to study this SVM MUD, and the results show that it can closely match the performance of the optimal Bayesian one-shot detector. Comparisons with an adaptive radial basis function (RBF) MUD trained by an unsupervised clustering algorithm are discussed.

'Putting it on the table': direct-manipulative interaction and multi-user display technologies for semi-immersive environments and augmented reality applications.

PubMed

Encarnação, L Miguel; Bimber, Oliver

2002-01-01

Collaborative virtual environments for diagnosis and treatment planning are increasingly gaining importance in our global society. Virtual and Augmented Reality approaches promised to provide valuable means for the involved interactive data analysis, but the underlying technologies still create a cumbersome work environment that is inadequate for clinical employment. This paper addresses two of the shortcomings of such technology: Intuitive interaction with multi-dimensional data in immersive and semi-immersive environments as well as stereoscopic multi-user displays combining the advantages of Virtual and Augmented Reality technology.

A software for managing chemical processes in a multi-user laboratory

DOE PAGES

Camino, Fernando E.

2016-10-26

Here, we report a software for logging chemical processes in a multi-user laboratory, which implements a work flow designed to reduce hazardous situations associated with the disposal of chemicals in incompatible waste containers. The software allows users to perform only those processes displayed in their list of authorized chemical processes and provides the location and label code of waste containers, among other useful information. The software has been used for six years in the cleanroom of the Center for Functional Nanomaterials at Brookhaven National Laboratory and has been an important factor for the excellent safety record of the Center.

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.

Robust Transceiver Design for Multiuser MIMO Downlink with Channel Uncertainties

NASA Astrophysics Data System (ADS)

Miao, Wei; Li, Yunzhou; Chen, Xiang; Zhou, Shidong; Wang, Jing

This letter addresses the problem of robust transceiver design for the multiuser multiple-input-multiple-output (MIMO) downlink where the channel state information at the base station (BS) is imperfect. A stochastic approach which minimizes the expectation of the total mean square error (MSE) of the downlink conditioned on the channel estimates under a total transmit power constraint is adopted. The iterative algorithm reported in [2] is improved to handle the proposed robust optimization problem. Simulation results show that our proposed robust scheme effectively reduces the performance loss due to channel uncertainties and outperforms existing methods, especially when the channel errors of the users are different.

Peer-to-peer Monte Carlo simulation of photon migration in topical applications of biomedical optics

NASA Astrophysics Data System (ADS)

Doronin, Alexander; Meglinski, Igor

2012-09-01

In the framework of further development of the unified approach of photon migration in complex turbid media, such as biological tissues we present a peer-to-peer (P2P) Monte Carlo (MC) code. The object-oriented programming is used for generalization of MC model for multipurpose use in various applications of biomedical optics. The online user interface providing multiuser access is developed using modern web technologies, such as Microsoft Silverlight, ASP.NET. The emerging P2P network utilizing computers with different types of compute unified device architecture-capable graphics processing units (GPUs) is applied for acceleration and to overcome the limitations, imposed by multiuser access in the online MC computational tool. The developed P2P MC was validated by comparing the results of simulation of diffuse reflectance and fluence rate distribution for semi-infinite scattering medium with known analytical results, results of adding-doubling method, and with other GPU-based MC techniques developed in the past. The best speedup of processing multiuser requests in a range of 4 to 35 s was achieved using single-precision computing, and the double-precision computing for floating-point arithmetic operations provides higher accuracy.

Peer-to-peer Monte Carlo simulation of photon migration in topical applications of biomedical optics.

PubMed

Doronin, Alexander; Meglinski, Igor

2012-09-01

In the framework of further development of the unified approach of photon migration in complex turbid media, such as biological tissues we present a peer-to-peer (P2P) Monte Carlo (MC) code. The object-oriented programming is used for generalization of MC model for multipurpose use in various applications of biomedical optics. The online user interface providing multiuser access is developed using modern web technologies, such as Microsoft Silverlight, ASP.NET. The emerging P2P network utilizing computers with different types of compute unified device architecture-capable graphics processing units (GPUs) is applied for acceleration and to overcome the limitations, imposed by multiuser access in the online MC computational tool. The developed P2P MC was validated by comparing the results of simulation of diffuse reflectance and fluence rate distribution for semi-infinite scattering medium with known analytical results, results of adding-doubling method, and with other GPU-based MC techniques developed in the past. The best speedup of processing multiuser requests in a range of 4 to 35 s was achieved using single-precision computing, and the double-precision computing for floating-point arithmetic operations provides higher accuracy.

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

The ATLAS multi-user upgrade and potential applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mustapha, B.; Nolen, J. A.; Savard, G.

With the recent integration of the CARIBU-EBIS charge breeder into the ATLAS accelerator system to provide for more pure and efficient charge breeding of radioactive beams, a multi-user upgrade of the ATLAS facility is being proposed to serve multiple users simultaneously. ATLAS was the first superconducting ion linac in the world and is the US DOE low-energy Nuclear Physics National User Facility. The proposed upgrade will take advantage of the continuous-wave nature of ATLAS and the pulsed nature of the EBIS charge breeder in order to simultaneously accelerate two beams with very close mass-to-charge ratios; one stable from the existingmore » ECR ion source and one radioactive from the newly commissioned EBIS charge breeder. In addition to enhancing the nuclear physics program, beam extraction at different points along the linac will open up the opportunity for other potential applications; for instance, material irradiation studies at ~ 1 MeV/u and isotope production at ~ 6 MeV/u or at the full ATLAS energy of ~ 15 MeV/u. The concept and proposed implementation of the ATLAS multi-user upgrade will be presented. Future plans to enhance the flexibility of this upgrade will also be presented.« less

The ATLAS multi-user upgrade and potential applications

NASA Astrophysics Data System (ADS)

Mustapha, B.; Nolen, J. A.; Savard, G.; Ostroumov, P. N.

2017-12-01

With the recent integration of the CARIBU-EBIS charge breeder into the ATLAS accelerator system to provide for more pure and efficient charge breeding of radioactive beams, a multi-user upgrade of the ATLAS facility is being proposed to serve multiple users simultaneously. ATLAS was the first superconducting ion linac in the world and is the US DOE low-energy Nuclear Physics National User Facility. The proposed upgrade will take advantage of the continuous-wave nature of ATLAS and the pulsed nature of the EBIS charge breeder in order to simultaneously accelerate two beams with very close mass-to-charge ratios; one stable from the existing ECR ion source and one radioactive from the newly commissioned EBIS charge breeder. In addition to enhancing the nuclear physics program, beam extraction at different points along the linac will open up the opportunity for other potential applications; for instance, material irradiation studies at ~1 MeV/u, isotope production and radiobiological studies at ~6 MeV/u and at the full ATLAS energy of ~15 MeV/u. The concept and proposed implementation of the ATLAS multi-user upgrade will be discussed. Future plans to enhance the flexibility of this upgrade will be presented.

Documenting clinical pharmacist intervention before and after the introduction of a web-based tool.

PubMed

Nurgat, Zubeir A; Al-Jazairi, Abdulrazaq S; Abu-Shraie, Nada; Al-Jedai, Ahmed

2011-04-01

To develop a database for documenting pharmacist intervention through a web-based application. The secondary endpoint was to determine if the new, web-based application provides any benefits with regards to documentation compliance by clinical pharmacists and ease of calculating cost savings compared with our previous method of documenting pharmacist interventions. A tertiary care hospital in Saudi Arabia. The documentation of interventions using a web-based documentation application was retrospectively compared with previous methods of documentation of clinical pharmacists' interventions (multi-user PC software). The number and types of interventions recorded by pharmacists, data mining of archived data, efficiency, cost savings, and the accuracy of the data generated. The number of documented clinical interventions increased from 4,926, using the multi-user PC software, to 6,840 for the web-based application. On average, we observed 653 interventions per clinical pharmacist using the web-based application, which showed an increase compared to an average of 493 interventions using the old multi-user PC software. However, using a paired Student's t-test there was no statistical significance difference between the two means (P = 0.201). Using a χ² test, which captured management level and the type of system used, we found a strong effect of management level (P < 2.2 × 10⁻¹⁶) on the number of documented interventions. We also found a moderately significant relationship between educational level and the number of interventions documented (P = 0.045). The mean ± SD time required to document an intervention using the web-based application was 66.55 ± 8.98 s. Using the web-based application, 29.06% of documented interventions resulted in cost-savings, while using the multi-user PC software only 4.75% of interventions did so. The majority of cost savings across both platforms resulted from the discontinuation of unnecessary drugs and a change in dosage regimen. Data collection using the web-based application was consistently more complete when compared to the multi-user PC software. The web-based application is an efficient system for documenting pharmacist interventions. Its flexibility and accessibility, as well as its detailed report functionality is a useful tool that will hopefully encourage other primary and secondary care facilities to adopt similar applications.

The standard calibration instrument automation system for the atomic absorption spectrophotometer. Part 3: Program documentation

NASA Astrophysics Data System (ADS)

Ryan, D. P.; Roth, G. S.

1982-04-01

Complete documentation of the 15 programs and 11 data files of the EPA Atomic Absorption Instrument Automation System is presented. The system incorporates the following major features: (1) multipoint calibration using first, second, or third degree regression or linear interpolation, (2) timely quality control assessments for spiked samples, duplicates, laboratory control standards, reagent blanks, and instrument check standards, (3) reagent blank subtraction, and (4) plotting of calibration curves and raw data peaks. The programs of this system are written in Data General Extended BASIC, Revision 4.3, as enhanced for multi-user, real-time data acquisition. They run in a Data General Nova 840 minicomputer under the operating system RDOS, Revision 6.2. There is a functional description, a symbol definitions table, a functional flowchart, a program listing, and a symbol cross reference table for each program. The structure of every data file is also detailed.

Japanese plan for SSF utilization

NASA Technical Reports Server (NTRS)

Mizuno, Toshio

1992-01-01

The Japanese Experiment Module (JEM) program has made significant progress. The JEM preliminary design review was completed in July 1992; construction of JEM operation facilities has begun; and the micro-G airplane, drop shaft, and micro-G experiment rocket are all operational. The national policy for JEM utilization was also established. The Space Experiment Laboratory (SEL) opened in June '92 and will function as a user support center. Eight JEM multiuser facilities are in phase B, and scientific requirements are being defined for 17 candidate multiuser facilities. The National Joint Research Program is about to start. Precursor missions and early Space Station utilization activities are being defined. This paper summarizes the program in outline and graphic form.

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.

Distributed Compressive CSIT Estimation and Feedback for FDD Multi-User Massive MIMO Systems

NASA Astrophysics Data System (ADS)

Rao, Xiongbin; Lau, Vincent K. N.

2014-06-01

To fully utilize the spatial multiplexing gains or array gains of massive MIMO, the channel state information must be obtained at the transmitter side (CSIT). However, conventional CSIT estimation approaches are not suitable for FDD massive MIMO systems because of the overwhelming training and feedback overhead. In this paper, we consider multi-user massive MIMO systems and deploy the compressive sensing (CS) technique to reduce the training as well as the feedback overhead in the CSIT estimation. The multi-user massive MIMO systems exhibits a hidden joint sparsity structure in the user channel matrices due to the shared local scatterers in the physical propagation environment. As such, instead of naively applying the conventional CS to the CSIT estimation, we propose a distributed compressive CSIT estimation scheme so that the compressed measurements are observed at the users locally, while the CSIT recovery is performed at the base station jointly. A joint orthogonal matching pursuit recovery algorithm is proposed to perform the CSIT recovery, with the capability of exploiting the hidden joint sparsity in the user channel matrices. We analyze the obtained CSIT quality in terms of the normalized mean absolute error, and through the closed-form expressions, we obtain simple insights into how the joint channel sparsity can be exploited to improve the CSIT recovery performance.

The right view from the wrong location: depth perception in stereoscopic multi-user virtual environments.

PubMed

Pollock, Brice; Burton, Melissa; Kelly, Jonathan W; Gilbert, Stephen; Winer, Eliot

2012-04-01

Stereoscopic depth cues improve depth perception and increase immersion within virtual environments (VEs). However, improper display of these cues can distort perceived distances and directions. Consider a multi-user VE, where all users view identical stereoscopic images regardless of physical location. In this scenario, cues are typically customized for one "leader" equipped with a head-tracking device. This user stands at the center of projection (CoP) and all other users ("followers") view the scene from other locations and receive improper depth cues. This paper examines perceived depth distortion when viewing stereoscopic VEs from follower perspectives and the impact of these distortions on collaborative spatial judgments. Pairs of participants made collaborative depth judgments of virtual shapes viewed from the CoP or after displacement forward or backward. Forward and backward displacement caused perceived depth compression and expansion, respectively, with greater compression than expansion. Furthermore, distortion was less than predicted by a ray-intersection model of stereo geometry. Collaboration times were significantly longer when participants stood at different locations compared to the same location, and increased with greater perceived depth discrepancy between the two viewing locations. These findings advance our understanding of spatial distortions in multi-user VEs, and suggest a strategy for reducing distortion.

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.

MAI statistics estimation and analysis in a DS-CDMA system

NASA Astrophysics Data System (ADS)

Alami Hassani, A.; Zouak, M.; Mrabti, M.; Abdi, F.

2018-05-01

A primary limitation of Direct Sequence Code Division Multiple Access DS-CDMA link performance and system capacity is multiple access interference (MAI). To examine the performance of CDMA systems in the presence of MAI, i.e., in a multiuser environment, several works assumed that the interference can be approximated by a Gaussian random variable. In this paper, we first develop a new and simple approach to characterize the MAI in a multiuser system. In addition to statistically quantifying the MAI power, the paper also proposes a statistical model for both variance and mean of the MAI for synchronous and asynchronous CDMA transmission. We show that the MAI probability density function (PDF) is Gaussian for the equal-received-energy case and validate it by computer simulations.

jsc2018m000314_Spinning_Science_Multi-use_Variable-g_Platform_Arrives_at_the_Space_Station-MP4

NASA Image and Video Library

2018-05-09

Spinning Science: Multi-use Variable-g Platform Arrives at the Space Station --- The Multi-use Variable-gravity Platform (MVP) Validation mission will install and test the MVP, a new hardware platform developed and owned by Techshot Inc., on the International Space Station (ISS). Though the MVP is designed for research with many different kinds of organisms and cell types, this validation mission will focus on Drosophila melanogaster, more commonly known as the fruit fly. This platform will be especially important for fruit fly research, as it will allow researchers to study larger sample sizes of Drosophila melanogaster than in other previous hardware utilizing centrifuges and it will be able to support fly colonies for multiple generations.

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.

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.

Investigation on iterative multiuser detection physical layer network coding in two-way relay free-space optical links with turbulences and pointing errors.

PubMed

Abu-Almaalie, Zina; Ghassemlooy, Zabih; Bhatnagar, Manav R; Le-Minh, Hoa; Aslam, Nauman; Liaw, Shien-Kuei; Lee, It Ee

2016-11-20

Physical layer network coding (PNC) improves the throughput in wireless networks by enabling two nodes to exchange information using a minimum number of time slots. The PNC technique is proposed for two-way relay channel free space optical (TWR-FSO) communications with the aim of maximizing the utilization of network resources. The multipair TWR-FSO is considered in this paper, where a single antenna on each pair seeks to communicate via a common receiver aperture at the relay. Therefore, chip interleaving is adopted as a technique to separate the different transmitted signals at the relay node to perform PNC mapping. Accordingly, this scheme relies on the iterative multiuser technique for detection of users at the receiver. The bit error rate (BER) performance of the proposed system is examined under the combined influences of atmospheric loss, turbulence-induced channel fading, and pointing errors (PEs). By adopting the joint PNC mapping with interleaving and multiuser detection techniques, the BER results show that the proposed scheme can achieve a significant performance improvement against the degrading effects of turbulences and PEs. It is also demonstrated that a larger number of simultaneous users can be supported with this new scheme in establishing a communication link between multiple pairs of nodes in two time slots, thereby improving the channel capacity.

Theoretical analysis of the performance of code division multiple access communications over multimode optical fiber channels. Part 1: Transmission and detection

NASA Astrophysics Data System (ADS)

Walker, Ernest L.

1994-05-01

This paper presents results of a theoretical investigation to evaluate the performance of code division multiple access communications over multimode optical fiber channels in an asynchronous, multiuser communication network environment. The system is evaluated using Gold sequences for spectral spreading of the baseband signal from each user employing direct-sequence biphase shift keying and intensity modulation techniques. The transmission channel model employed is a lossless linear system approximation of the field transfer function for the alpha -profile multimode optical fiber. Due to channel model complexity, a correlation receiver model employing a suboptimal receive filter was used in calculating the peak output signal at the ith receiver. In Part 1, the performance measures for the system, i.e., signal-to-noise ratio and bit error probability for the ith receiver, are derived as functions of channel characteristics, spectral spreading, number of active users, and the bit energy to noise (white) spectral density ratio. In Part 2, the overall system performance is evaluated.

Low-Complexity User Selection for Rate Maximization in MIMO Broadcast Channels with Downlink Beamforming

PubMed Central

Silva, Adão; Gameiro, Atílio

2014-01-01

We present in this work a low-complexity algorithm to solve the sum rate maximization problem in multiuser MIMO broadcast channels with downlink beamforming. Our approach decouples the user selection problem from the resource allocation problem and its main goal is to create a set of quasiorthogonal users. The proposed algorithm exploits physical metrics of the wireless channels that can be easily computed in such a way that a null space projection power can be approximated efficiently. Based on the derived metrics we present a mathematical model that describes the dynamics of the user selection process which renders the user selection problem into an integer linear program. Numerical results show that our approach is highly efficient to form groups of quasiorthogonal users when compared to previously proposed algorithms in the literature. Our user selection algorithm achieves a large portion of the optimum user selection sum rate (90%) for a moderate number of active users. PMID:24574928

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.

LiFi: transforming fibre into wireless

NASA Astrophysics Data System (ADS)

Yin, Liang; Islim, Mohamed Sufyan; Haas, Harald

2017-01-01

Light-fidelity (LiFi) uses energy-efficient light-emitting diodes (LEDs) for high-speed wireless communication, and it has a great potential to be integrated with fibre communication for future gigabit networks. However, by making fibre communication wireless, multiuser interference arises. Traditional methods use orthogonal multiple access (OMA) for interference avoidance. In this paper, multiuser interference is exploited with the use of non-orthogonal multiple access (NOMA) relying on successive interference cancellation (SIC). The residual interference due to imperfect SIC in practical scenarios is characterized with a proportional model. Results show that NOMA offers 5 -10 dB gain on the equivalent signal-to-interference-plus-noise ratio (SINR) over OMA. The bit error rate (BER) performance of direct current optical orthogonal frequency division multiplexing (DCO-OFDM) is shown to be significantly improved when SIC is used.

Two-dimensional quantum repeaters

NASA Astrophysics Data System (ADS)

Wallnöfer, J.; Zwerger, M.; Muschik, C.; Sangouard, N.; Dür, W.

2016-11-01

The endeavor to develop quantum networks gave rise to a rapidly developing field with far-reaching applications such as secure communication and the realization of distributed computing tasks. This ultimately calls for the creation of flexible multiuser structures that allow for quantum communication between arbitrary pairs of parties in the network and facilitate also multiuser applications. To address this challenge, we propose a two-dimensional quantum repeater architecture to establish long-distance entanglement shared between multiple communication partners in the presence of channel noise and imperfect local control operations. The scheme is based on the creation of self-similar multiqubit entanglement structures at growing scale, where variants of entanglement swapping and multiparty entanglement purification are combined to create high-fidelity entangled states. We show how such networks can be implemented using trapped ions in cavities.

Antimicrobial efficacy assessment of multi-use solution to disinfect hydrophilic contact lens, in vitro.

PubMed

Lui, Aline Cristina Fioravanti; Netto, Adamo Lui; Silva, Cely Barreto da; Hida, Richard; Mendes, Thais Sousa; Lui, Giovana Arlene Fioravanti; Gemperli, Daniela Barbosa; Vital, Enderson Dantas

2009-01-01

To evaluate the efficacy of disinfecting solutions in hydrophilic contact lenses (CL). Two multi-use solutions denominated solution A (0.001% polyquaternium-1 and 0.0005% myristamidopropyl dimethylamine) and solution B (0.0001% polyaminopropyl biguanide) were used. The solutions were tested in hydrophilic contact lenses infected with Pseudomonas aeruginosa (ATCC27583), Staphylococcus epidermidis (ATCC1226), Klebsiella pneumoniae (ATCC13883), Staphylococcus aureus (ATCC25923) and Candida albicans (ATCC 10231) and the decrease in microorganisms growth after the hydrophilic contact lenses were cleaned with the respective solutions was verified. The manufacture's instructions were followed. A decrease of 90% of Pseudomonas aeruginosa, Staphylococcus epidermidis, Staphylococcus aureus, Candida albicans and a decrease 100% of Klebsiella pneumoniae was observed. The solutions decreased the amount of microorganisms tested.

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

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

2014-01-01

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. 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. 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. 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.

Computer-Mediated Peer Review of Student Papers.

ERIC Educational Resources Information Center

Sullivan, Dave; Brown, Carol E.; Nielson, Norma L.

1998-01-01

Barriers to peer review of student work can be overcome using computer-mediated systems ranging from customized software to e-mail, multiuser object-oriented systems (MOOs), and Web-based projects. (SK)

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.

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.

SmallTool - a toolkit for realizing shared virtual environments on the Internet

NASA Astrophysics Data System (ADS)

Broll, Wolfgang

1998-09-01

With increasing graphics capabilities of computers and higher network communication speed, networked virtual environments have become available to a large number of people. While the virtual reality modelling language (VRML) provides users with the ability to exchange 3D data, there is still a lack of appropriate support to realize large-scale multi-user applications on the Internet. In this paper we will present SmallTool, a toolkit to support shared virtual environments on the Internet. The toolkit consists of a VRML-based parsing and rendering library, a device library, and a network library. This paper will focus on the networking architecture, provided by the network library - the distributed worlds transfer and communication protocol (DWTP). DWTP provides an application-independent network architecture to support large-scale multi-user environments on the Internet.

Zadoff-Chu sequence-based hitless ranging scheme for OFDMA-PON configured 5G fronthaul uplinks

NASA Astrophysics Data System (ADS)

Reza, Ahmed Galib; Rhee, June-Koo Kevin

2017-05-01

A Zadoff-Chu (ZC) sequence-based low-complexity hitless upstream time synchronization scheme is proposed for an orthogonal frequency division multiple access passive optical network configured cloud radio access network fronthaul. The algorithm is based on gradual loading of the ZC sequences, where the phase discontinuity due to the cyclic prefix is alleviated by a frequency domain phase precoder, eliminating the requirements of guard bands to mitigate intersymbol interference and inter-carrier interference. Simulation results for uncontrolled-wavelength asynchronous transmissions from four concurrent transmitting optical network units are presented to demonstrate the effectiveness of the proposed scheme.

Trip internalization in multi-use developments : [summary].

DOT National Transportation Integrated Search

2014-04-01

Gas prices and fossil fuel concerns have promoted : reduced car use. More people are seeking : housing within a walk, bike, or shorter drive of : important destinations, leading to more mixed : use developments (MXD) with internal retail sites, : red...

Joint channel estimation and multi-user detection for multipath fading channels in DS-CDMA systems

NASA Astrophysics Data System (ADS)

Wu, Sau-Hsuan; Kuo, C.-C. Jay

2002-11-01

The technique of joint blind channel estimation and multiple access interference (MAI) suppression for an asynchronous code-division multiple-access (CDMA) system is investigated in this research. To identify and track dispersive time-varying fading channels and to avoid the phase ambiguity that come with the second-order statistic approaches, a sliding-window scheme using the expectation maximization (EM) algorithm is proposed. The complexity of joint channel equalization and symbol detection for all users increases exponentially with system loading and the channel memory. The situation is exacerbated if strong inter-symbol interference (ISI) exists. To reduce the complexity and the number of samples required for channel estimation, a blind multiuser detector is developed. Together with multi-stage interference cancellation using soft outputs provided by this detector, our algorithm can track fading channels with no phase ambiguity even when channel gains attenuate close to zero.

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.

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.

Design of pulse waveform for waveform division multiple access UWB wireless communication system.

PubMed

Yin, Zhendong; Wang, Zhirui; Liu, Xiaohui; Wu, Zhilu

2014-01-01

A new multiple access scheme, Waveform Division Multiple Access (WDMA) based on the orthogonal wavelet function, is presented. After studying the correlation properties of different categories of single wavelet functions, the one with the best correlation property will be chosen as the foundation for combined waveform. In the communication system, each user is assigned to different combined orthogonal waveform. Demonstrated by simulation, combined waveform is more suitable than single wavelet function to be a communication medium in WDMA system. Due to the excellent orthogonality, the bit error rate (BER) of multiuser with combined waveforms is so close to that of single user in a synchronous system. That is to say, the multiple access interference (MAI) is almost eliminated. Furthermore, even in an asynchronous system without multiuser detection after matched filters, the result is still pretty ideal and satisfactory by using the third combination mode that will be mentioned in the study.

Action tagging in a multi-user indoor environment for behavioural analysis purposes.

PubMed

Guerra, Claudio; Bianchi, Valentina; De Munari, Ilaria; Ciampolini, Paolo

2015-01-01

EU population is getting older, so that ICT-based solutions are expected to provide support in the challenges implied by the demographic change. At the University of Parma an AAL (Ambient Assisted Living) system, named CARDEA, has been developed. In this paper a new feature of the system is introduced, in which environmental and personal (i.e., wearable) sensors coexist, providing an accurate picture of the user's activity and needs. Environmental devices may greatly help in performing activity recognition and behavioral analysis tasks. However, in a multi-user environment, this implies the need of attributing environmental sensors outcome to a specific user, i.e., identifying the user when he performs a task detected by an environmental device. We implemented such an "action tagging" feature, based on information fusion, within the CARDEA environment, as an inexpensive, alternative solution to the problematic issue of indoor locationing.

Performance Analysis of Diversity-Controlled Multi-User Superposition Transmission for 5G Wireless Networks

PubMed Central

Yeom, Jeong Seon; Jung, Bang Chul; Jin, Hu

2018-01-01

In this paper, we propose a novel low-complexity multi-user superposition transmission (MUST) technique for 5G downlink networks, which allows multiple cell-edge users to be multiplexed with a single cell-center user. We call the proposed technique diversity-controlled MUST technique since the cell-center user enjoys the frequency diversity effect via signal repetition over multiple orthogonal frequency division multiplexing (OFDM) sub-carriers. We assume that a base station is equipped with a single antenna but users are equipped with multiple antennas. In addition, we assume that the quadrature phase shift keying (QPSK) modulation is used for users. We mathematically analyze the bit error rate (BER) of both cell-edge users and cell-center users, which is the first theoretical result in the literature to the best of our knowledge. The mathematical analysis is validated through extensive link-level simulations. PMID:29439413

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

NASA Astrophysics Data System (ADS)

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

2004-05-01

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).

Performance of a novel LED lamp arrangement to reduce SNR fluctuation for multi-user visible light communication systems.

PubMed

Wang, Zixiong; Yu, Changyuan; Zhong, Wen-De; Chen, Jian; Chen, Wei

2012-02-13

This paper investigates the performance of our recently proposed LED lamp arrangement to reduce the SNR fluctuation from different locations in the room for multi-user visible light communications. The LED lamp arrangement consists of 4 LED lamps positioned in the corners and 12 LED lamps spread evenly on a circle. Our studies show that the SNR fluctuation under such a LED lamp arrangement is reduced from 14.5 dB to 0.9 dB, which guarantees that users can obtain almost identical communication quality, regardless of their locations. After time domain zero-forcing (ZF) equalization, the BER performances and channel capacities of 100-Mbit/s and 200-Mbit/s bipolar on-off-keying (OOK) signal with most significant inter-symbol interference (ISI) are very close to that of the channel without any ISI caused by this LED lamp arrangement.

Performance Analysis of Diversity-Controlled Multi-User Superposition Transmission for 5G Wireless Networks.

PubMed

Yeom, Jeong Seon; Chu, Eunmi; Jung, Bang Chul; Jin, Hu

2018-02-10

In this paper, we propose a novel low-complexity multi-user superposition transmission (MUST) technique for 5G downlink networks, which allows multiple cell-edge users to be multiplexed with a single cell-center user. We call the proposed technique diversity-controlled MUST technique since the cell-center user enjoys the frequency diversity effect via signal repetition over multiple orthogonal frequency division multiplexing (OFDM) sub-carriers. We assume that a base station is equipped with a single antenna but users are equipped with multiple antennas. In addition, we assume that the quadrature phase shift keying (QPSK) modulation is used for users. We mathematically analyze the bit error rate (BER) of both cell-edge users and cell-center users, which is the first theoretical result in the literature to the best of our knowledge. The mathematical analysis is validated through extensive link-level simulations.

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

Multiuser Droplet Combustion Apparatus Developed to Conduct Combustion Experiments

NASA Technical Reports Server (NTRS)

Myhre, Craig A.

2001-01-01

A major portion of the energy produced in the world today comes from the combustion or burning of liquid hydrocarbon fuels in the form of droplets. However, despite vigorous scientific examinations for over a century, researchers still lack a full understanding of many fundamental combustion processes of liquid fuels. Understanding how these fuel droplets ignite, spread, and extinguish themselves will help us develop more efficient ways of energy production and propulsion, as well as help us deal better with the problems of combustion-generated pollution and fire hazards associated with liquid combustibles. The ability to conduct more controlled experiments in space, without the complication of gravity, provides scientists with an opportunity to examine these complicated processes closely. The Multiuser Droplet Combustion Apparatus (MDCA) supports this continued research under microgravity conditions. The objectives are to improve understanding of fundamental droplet phenomena affected by gravity, to use research results to advance droplet combustion science and technology on Earth, and to address issues of fire hazards associated with liquid combustibles on Earth and in space. MDCA is a multiuser facility designed to accommodate different combustion science experiments. The modular approach permits the on-orbit replacement of droplet combustion principal investigator experiments such as different fuels, droplet-dispensing needles, and droplet-tethering mechanisms. Large components such as the avionics, diagnostics, and base-plate remain on the International Space Station to reduce the launch mass of new experiments. MDCA is also designed to operate in concert with ground systems on Earth to minimize the involvement of the crew during orbit.

Microcomputers in Libraries: The Quiet Revolution.

ERIC Educational Resources Information Center

Boss, Richard

1985-01-01

This article defines three separate categories of microcomputers--personal, desk-top, multi-user devices--and relates storage capabilities (expandability, floppy disks) to library applications. Highlghts include de facto standards, operating systems, database management systems, applications software, circulation control systems, dumb and…

Trip internalization in multi-use developments.

DOT National Transportation Integrated Search

2014-04-01

Internal trip capture refers to how the number trips to and from a development are reduced by the proximity of : complementary land uses within the development (e.g., residential to retail). Internal trips occur within the : development and do not en...

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 additional questions posed by potential proposers. After amending the AFP and posting additional material for potential users to consider, proposals are being accepted until July 31, at which point they will be evaluated to determine the proposer which best meets the objectives of the government. By identifying VAB HB2 as available and seeking proposals from the commercial sector for VAB HB2 and MLP use, Center Planning and Development is ensuring Kennedy Space Centers relevance in the evolving launch industry of the 21st century.

Bridging Media with the Help of Players

NASA Astrophysics Data System (ADS)

Nitsche, Michael; Drake, Matthew; Murray, Janet

We suggest harvesting the power of multiplayer design to bridge content across different media platforms and develop player-driven cross-media experiences. This paper first argues to partially replace complex AI systems with multiplayer design strategies to provide the necessary level of flexibility in the content generation for cross-media applications. The second part describes one example project - the Next Generation Play (NGP) project - that illustrates one practical approach of such a player-driven cross-media content generation. NGP allows players to collect virtual items while watching a TV show. These items are re-used in a multiplayer casual game that automatically generates new game worlds based on the various collections of active players joining a game session. While the TV experience is designed for the single big screen, the game executes on multiple mobile phones. Design and technical implementation of the prototype are explained in more detail to clarify how players carry elements of television narratives into a non-linear handheld gaming experience. The system describes a practical way to create casual game adaptations based on players' personal preferences in a multi-user environment.

An efficient and scalable deformable model for virtual reality-based medical applications.

PubMed

Choi, Kup-Sze; Sun, Hanqiu; Heng, Pheng-Ann

2004-09-01

Modeling of tissue deformation is of great importance to virtual reality (VR)-based medical simulations. Considerable effort has been dedicated to the development of interactively deformable virtual tissues. In this paper, an efficient and scalable deformable model is presented for virtual-reality-based medical applications. It considers deformation as a localized force transmittal process which is governed by algorithms based on breadth-first search (BFS). The computational speed is scalable to facilitate real-time interaction by adjusting the penetration depth. Simulated annealing (SA) algorithms are developed to optimize the model parameters by using the reference data generated with the linear static finite element method (FEM). The mechanical behavior and timing performance of the model have been evaluated. The model has been applied to simulate the typical behavior of living tissues and anisotropic materials. Integration with a haptic device has also been achieved on a generic personal computer (PC) platform. The proposed technique provides a feasible solution for VR-based medical simulations and has the potential for multi-user collaborative work in virtual environment.

FLASH2: Operation, beamlines, and photon diagnostics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Plönjes, Elke, E-mail: elke.ploenjes@desy.de; Faatz, Bart; Kuhlmann, Marion

2016-07-27

FLASH2, a major extension of the soft X-ray free-electron laser FLASH at DESY, turns FLASH into a multi-user FEL facility. A new undulator line is located in a separate accelerator tunnel and driven additionally by the FLASH linear accelerator. First lasing of FLASH2 was achieved in August 2014 with simultaneous user operation at FLASH1. The new FLASH2 experimental hall offers space for up to six experimental end stations, some of which will be installed permanently. The wide wavelength range spans from 4-60 nm and 0.8 nm in the 5{sup th} harmonic and in the future deep into the water windowmore » in the fundamental. While this is of high interest to users, it is challenging from the beamline instrumentation point of view. Online diagnostics - which are mostly pulse resolved - for beam intensity, position, wavelength, wave front, and pulse length have been to a large extent developed at FLASH(1) and have now been optimized for FLASH2. Pump-probe facilities for XUV-XUV, XUV optical and XUV-THz experiments will complete the FLASH2 user facility.« less

Experiments on Four Different Techniques for Automatically Locating Land Vehicles - A Summary of Results

DOT National Transportation Integrated Search

1977-06-01

In 1975, to further the development and to refine and dmonstrate multiuser Automatic Vehicle Monitoring (AVM) application, the Urban Mass Transportation Administration and the Transportation Systems Center (TSC) initiated a two-phase program. Phase I...

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…

Brave New World

ERIC Educational Resources Information Center

Panettieri, Joseph C.

2007-01-01

Across the globe, progressive universities are embracing any number of MUVEs (multi-user virtual environments), 3D environments, and "immersive" virtual reality tools. And within the next few months, several universities are expected to test so-called "telepresence" videoconferencing systems from Cisco Systems and other leading…

800 MHz Communication Survey of the Los Angeles Area

DOT National Transportation Integrated Search

1979-01-01

During the first half of 1978, as part of the Multi-User Automatic Vehicle Monitoring (AVM) Program, a survey was conducted to determine the suitability of utilizing the 800-900 MHz band as the primary carrier of digital communication data pertaining...

Client-Server: What Is It and Are We There Yet?

ERIC Educational Resources Information Center

Gershenfeld, Nancy

1995-01-01

Discusses client-server architecture in dumb terminals, personal computers, local area networks, and graphical user interfaces. Focuses on functions offered by client personal computers: individualized environments; flexibility in running operating systems; advanced operating system features; multiuser environments; and centralized data…

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...

Social Interactions and Games

ERIC Educational Resources Information Center

Uz, Cigdem; Cagiltay, Kursat

2015-01-01

Digital games have become popular due to great technological improvements in recent years. They have been increasingly transformed from co-located experiences into multi-played, socially oriented platforms (Herodotou, 2009). Multi-User Online Games provide the opportunity to create a social environment for friendships and strengthen the…

Swanson in

NASA Image and Video Library

2014-06-11

ISS040-E-010261 (11 June 2014) --- NASA astronaut Steve Swanson, Expedition 40 commander, works with the Multi-user Drop Combustion Apparatus (MDCA) at a workstation in the Harmony node of the International Space Station. The MDCA contains hardware and software to conduct unique droplet combustion experiments in space.

Swanson in

NASA Image and Video Library

2014-06-11

ISS040-E-010258 (11 June 2014) --- NASA astronaut Steve Swanson, Expedition 40 commander, works with the Multi-user Drop Combustion Apparatus (MDCA) at a workstation in the Harmony node of the International Space Station. The MDCA contains hardware and software to conduct unique droplet combustion experiments in space.

UNIX: A Tool for Information Management.

ERIC Educational Resources Information Center

Frey, Dean

1989-01-01

Describes UNIX, a computer operating system that supports multi-task and multi-user operations. Characteristics that make it especially suitable for library applications are discussed, including a hierarchical file structure and utilities for text processing, database activities, and bibliographic work. Sources of information on hardware…

MUD and Self Efficacy.

ERIC Educational Resources Information Center

Lee, Kwan Min

2000-01-01

Proposes a theoretical framework for analyzing the effect of MUD (Multi-User Dungeons) playing on users' self-efficacy by applying Bandura's social learning theory, and introduces three types of self-efficacy: computer self-efficacy; social self-efficacy; and generalized self-efficacy. Considers successful performance, vicarious experience,…

Marky: a tool supporting annotation consistency in multi-user and iterative document annotation projects.

PubMed

Pérez-Pérez, Martín; Glez-Peña, Daniel; Fdez-Riverola, Florentino; Lourenço, Anália

2015-02-01

Document annotation is a key task in the development of Text Mining methods and applications. High quality annotated corpora are invaluable, but their preparation requires a considerable amount of resources and time. Although the existing annotation tools offer good user interaction interfaces to domain experts, project management and quality control abilities are still limited. Therefore, the current work introduces Marky, a new Web-based document annotation tool equipped to manage multi-user and iterative projects, and to evaluate annotation quality throughout the project life cycle. At the core, Marky is a Web application based on the open source CakePHP framework. User interface relies on HTML5 and CSS3 technologies. Rangy library assists in browser-independent implementation of common DOM range and selection tasks, and Ajax and JQuery technologies are used to enhance user-system interaction. Marky grants solid management of inter- and intra-annotator work. Most notably, its annotation tracking system supports systematic and on-demand agreement analysis and annotation amendment. Each annotator may work over documents as usual, but all the annotations made are saved by the tracking system and may be further compared. So, the project administrator is able to evaluate annotation consistency among annotators and across rounds of annotation, while annotators are able to reject or amend subsets of annotations made in previous rounds. As a side effect, the tracking system minimises resource and time consumption. Marky is a novel environment for managing multi-user and iterative document annotation projects. Compared to other tools, Marky offers a similar visually intuitive annotation experience while providing unique means to minimise annotation effort and enforce annotation quality, and therefore corpus consistency. Marky is freely available for non-commercial use at http://sing.ei.uvigo.es/marky. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

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.

Magnetic MIMO Signal Processing and Optimization for Wireless Power Transfer

NASA Astrophysics Data System (ADS)

Yang, Gang; Moghadam, Mohammad R. Vedady; Zhang, Rui

2017-06-01

In magnetic resonant coupling (MRC) enabled multiple-input multiple-output (MIMO) wireless power transfer (WPT) systems, multiple transmitters (TXs) each with one single coil are used to enhance the efficiency of simultaneous power transfer to multiple single-coil receivers (RXs) by constructively combining their induced magnetic fields at the RXs, a technique termed "magnetic beamforming". In this paper, we study the optimal magnetic beamforming design in a multi-user MIMO MRC-WPT system. We introduce the multi-user power region that constitutes all the achievable power tuples for all RXs, subject to the given total power constraint over all TXs as well as their individual peak voltage and current constraints. We characterize each boundary point of the power region by maximizing the sum-power deliverable to all RXs subject to their minimum harvested power constraints. For the special case without the TX peak voltage and current constraints, we derive the optimal TX current allocation for the single-RX setup in closed-form as well as that for the multi-RX setup. In general, the problem is a non-convex quadratically constrained quadratic programming (QCQP), which is difficult to solve. For the case of one single RX, we show that the semidefinite relaxation (SDR) of the problem is tight. For the general case with multiple RXs, based on SDR we obtain two approximate solutions by applying time-sharing and randomization, respectively. Moreover, for practical implementation of magnetic beamforming, we propose a novel signal processing method to estimate the magnetic MIMO channel due to the mutual inductances between TXs and RXs. Numerical results show that our proposed magnetic channel estimation and adaptive beamforming schemes are practically effective, and can significantly improve the power transfer efficiency and multi-user performance trade-off in MIMO MRC-WPT systems.

Multi-psychotropic drug prescription and the association to neuropsychiatric symptoms in three Norwegian nursing home cohorts between 2004 and 2011.

PubMed

Gulla, Christine; Selbaek, Geir; Flo, Elisabeth; Kjome, Reidun; Kirkevold, Øyvind; Husebo, Bettina S

2016-06-01

Neuropsychiatric symptoms, such as affective symptoms, psychosis, agitation, and apathy are common among nursing home patients with and without dementia. Treatment with one or more psychotropic drug is often without explicit clinical indication, despite low treatment efficacy, and potential side effects. We aim to investigate the multi-psychotropic drug use to identify factors and patient characteristics associated with multi-use. We analysed three cohorts from 129 Norwegian nursing homes, collected between 2004 and 2011. Patients (N = 4739) were assessed with the Neuropsychiatric Inventory - Nursing Home version (NPI-NH), Clinical Dementia Rating scale, and Physical Self Maintenance Scale. We used ordinal logistic regression to analyse associations between psychotropics (antidepressants, antipsychotics, anxiolytics, hypnotics, and anti-dementia drugs), patient characteristics, and neuropsychiatric symptoms. Patients used on average 6.6 drugs; 27 % used no psychotropics, 32 % one, and 41 % multiple psychotropic drugs (24 % two, 17 % ≥3). Thirty-nine percent were prescribed antidepressants, 30 % sedatives, 24 % anxiolytics, and 20 % antipsychotics. The total NPI-NH score was associated with multi-use (OR 1.02, 95 % CI 1.02-1.03), and increased from a mean of 13.5 (SD 16.3) for patients using none, to 25.5 (21.8) for patients using ≥3 psychotropics. Affective symptoms (depression and anxiety) were most strongly associated with multi-psychotropic drug use (OR 1.10, 95 % CI: 1.09-1.12). Female gender, independency in daily living, younger age, dementia, and many regular drugs were also associated with multi-use. Forty-one percent were exposed to multi-psychotropic drug prescriptions. Contrary to current evidence and guidelines, there is an extensive use of multiple psychotropic drugs in patients with severe NPS and dementia.

Reservoir Computing Properties of Neural Dynamics in Prefrontal Cortex

PubMed Central

Procyk, Emmanuel; Dominey, Peter Ford

2016-01-01

Primates display a remarkable ability to adapt to novel situations. Determining what is most pertinent in these situations is not always possible based only on the current sensory inputs, and often also depends on recent inputs and behavioral outputs that contribute to internal states. Thus, one can ask how cortical dynamics generate representations of these complex situations. It has been observed that mixed selectivity in cortical neurons contributes to represent diverse situations defined by a combination of the current stimuli, and that mixed selectivity is readily obtained in randomly connected recurrent networks. In this context, these reservoir networks reproduce the highly recurrent nature of local cortical connectivity. Recombining present and past inputs, random recurrent networks from the reservoir computing framework generate mixed selectivity which provides pre-coded representations of an essentially universal set of contexts. These representations can then be selectively amplified through learning to solve the task at hand. We thus explored their representational power and dynamical properties after training a reservoir to perform a complex cognitive task initially developed for monkeys. The reservoir model inherently displayed a dynamic form of mixed selectivity, key to the representation of the behavioral context over time. The pre-coded representation of context was amplified by training a feedback neuron to explicitly represent this context, thereby reproducing the effect of learning and allowing the model to perform more robustly. This second version of the model demonstrates how a hybrid dynamical regime combining spatio-temporal processing of reservoirs, and input driven attracting dynamics generated by the feedback neuron, can be used to solve a complex cognitive task. We compared reservoir activity to neural activity of dorsal anterior cingulate cortex of monkeys which revealed similar network dynamics. We argue that reservoir computing is a pertinent framework to model local cortical dynamics and their contribution to higher cognitive function. PMID:27286251

A Pilot Study of Determinants of Ongoing Participation in EnhanceFitness: A Community-Based Group Exercise Program for Older Adults.

PubMed

Gillette, David B; Petrescu-Prahova, Miruna; Herting, Jerald R; Belza, Basia

2015-01-01

Physical activity has many benefits for older adults, but adherence is often low. The purposes of this study were to (1) identify motivators and barriers for participation in EnhanceFitness (EF), a group-based exercise program; and (2) quantitatively examine the association between motivators, barriers and individual characteristics, and ongoing participation in the program. This was a prospective, cross-sectional study. We mailed a pilot, investigator-developed survey to assess motivators and barriers to exercising to 340 adults who started a new EF class, regardless of their attendance rate. We precoded surveys on the basis of class attendance, with former participants defined as having no attendance a month or more before a 4-month fitness check. Of the 241 respondents (71% response rate), 61 (25%) were precoded as former participants and 180 (75%) as current participants. The mean age of respondents was 71 years and they were predominately female (89%). More than half of respondents were whites (58%), and almost half were married (46%). Former participants reported lower total motivation scores than current participants (P < .01) and had a significantly higher mean total barrier score (P < .001). The effects of 5 barriers ("Class was too hard," "Class was too easy," "I don't like to exercise," "Personal illness," and "Exercise caused pain") and 2 motivators ("I want to exercise" and "I plan exercise as part of my day") were significantly different between current and former participants. Discrete event history models show that dropout was related positively to ethnicity (whites were more likely to drop out) and health-related barriers. In newly formed EF classes, participants who drop out report more program, psychosocial, and health barriers, and fewer program and psychosocial motivators. Total barrier score and health barriers significantly predict a participant's dropping out, and white ethnicity is associated with a higher likelihood of dropping out. Employing strategies that address health barriers to participation could improve attendance rates for group-based exercise programs.

iss055e036790

NASA Image and Video Library

2018-04-30

iss055e036790 (April 30, 2018) --- NASA astronaut Drew Feustel conducts science operations inside the Multi-use Variable-g Platform Module which enables research into how small organisms such as fruit flies, flatworms, plants, fish, cells, protein crystals and many others adapt to different types of gravity scenarios.

Special Technology Area Review on Micro-Opto-Electro-Mechanical-Systems (MOEMS)

DTIC Science & Technology

1997-12-01

Optical Interference in Night Vision Systems "* DMD Assisted Intelligent Manufacturing of ................................................... SRI...CONCEPT ......................................... p. 8 FIGURE 3(a): DMD LIGHT SWITCHES...p. 9 FIGURE 3(b): SEM PHOTOMICROGRAPHS OF DMD CHIPS ........................................ p. 9 FIGURE 4: MULTI-USER MEMS PROJECTS (MUMPS

CIR

NASA Image and Video Library

2014-06-11

ISS040-E-010496 (11 June 2014) --- NASA astronaut Steve Swanson, Expedition 40 commander, works with the Multi-user Drop Combustion Apparatus (MDCA) inside the Combustion Integrated Rack (CIR) in the Destiny laboratory of the International Space Station. The MDCA contains hardware and software to conduct unique droplet combustion experiments in space.

CIR

NASA Image and Video Library

2014-06-11

ISS040-E-010502 (11 June 2014) --- NASA astronaut Steve Swanson, Expedition 40 commander, works with the Multi-user Drop Combustion Apparatus (MDCA) inside the Combustion Integrated Rack (CIR) in the Destiny laboratory of the International Space Station. The MDCA contains hardware and software to conduct unique droplet combustion experiments in space.

Semiarid ECohydrological Array – SECA 2058

USDA-ARS?s Scientific Manuscript database

The Southwestern ECohydrology Array (SECA) is a multi-user network that serves to assess biosphere / atmospheric exchange processes, as well as surface hydrology in semiarid ecosystems. SECA is administered through the USDA-ARS Southwest Watershed Research Center and the University of Arizona’s B2 E...

Lake Harsha: Three Years of HABs Monitoring

EPA Science Inventory

USEPA’s Office of Research and Development has partnered with the Clermont County, OH Water Resources Department in an on-going study to assess HAB trends and develop monitoring tools and approaches. Lake Harsha, a multi-use reservoir and primary drinking water source in southwes...

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...

Multi-User Facilities for Molecular Marine Biology and Biotechnology

DTIC Science & Technology

1990-04-06

relatedness (or non-relatedness) of symbiotic zooxanthellae in corals. The DNA synthesizer is used to prepare universal primers for 18s r RNA. A...tunicates (Weissman lab) Robert Rowan - Zooxanthellae (Powers lab) Lani West - sponges/barnacles (Powers lab) Jeff Mitton - Mytilus (Powers lab) Kristi

Design and Verification of Remote Sensing Image Data Center Storage Architecture Based on Hadoop

NASA Astrophysics Data System (ADS)

Tang, D.; Zhou, X.; Jing, Y.; Cong, W.; Li, C.

2018-04-01

The data center is a new concept of data processing and application proposed in recent years. It is a new method of processing technologies based on data, parallel computing, and compatibility with different hardware clusters. While optimizing the data storage management structure, it fully utilizes cluster resource computing nodes and improves the efficiency of data parallel application. This paper used mature Hadoop technology to build a large-scale distributed image management architecture for remote sensing imagery. Using MapReduce parallel processing technology, it called many computing nodes to process image storage blocks and pyramids in the background to improve the efficiency of image reading and application and sovled the need for concurrent multi-user high-speed access to remotely sensed data. It verified the rationality, reliability and superiority of the system design by testing the storage efficiency of different image data and multi-users and analyzing the distributed storage architecture to improve the application efficiency of remote sensing images through building an actual Hadoop service system.

[EXPERIENCE IN THE APPLICATION OF DATABASES ON BLOODSUCKING INSECTS IN ZOOLOGICAL STUDIES].

PubMed

Medvedev, S G; Khalikov, R G

2016-01-01

The paper summarizes long-term experience of accumulating and summarizing the faunistic information by means of separate databases (DB) and information analytical systems (IAS), and also prospects of its representation by modern multi-user informational systems. The experience obtained during development and practical use of the PARHOST1 IAS for the study of the world flea fauna and work with personal databases created for the study of bloodsucking insects (lice and blackflies) is analyzed. Research collection material on type series of 57 species and subspecies of fleas of the fauna of Russia was approved as a part of multi-user information retrieval system on the web-portal of the Zoological Institute of the Russian Academy of Sciences. According former investigations, the system allows depositing the information in the authentic form and performing its gradual transformation, i. e. its unification and structuring. In order to provide continuity of DB refill, the possibility of work of operators with different degree of competence is provided.

Analysis of multiuser mixed RF/FSO relay networks for performance improvements in Cloud Computing-Based Radio Access Networks (CC-RANs)

NASA Astrophysics Data System (ADS)

Alimi, Isiaka A.; Monteiro, Paulo P.; Teixeira, António L.

2017-11-01

The key paths toward the fifth generation (5G) network requirements are towards centralized processing and small-cell densification systems that are implemented on the cloud computing-based radio access networks (CC-RANs). The increasing recognitions of the CC-RANs can be attributed to their valuable features regarding system performance optimization and cost-effectiveness. Nevertheless, realization of the stringent requirements of the fronthaul that connects the network elements is highly demanding. In this paper, considering the small-cell network architectures, we present multiuser mixed radio-frequency/free-space optical (RF/FSO) relay networks as feasible technologies for the alleviation of the stringent requirements in the CC-RANs. In this study, we use the end-to-end (e2e) outage probability, average symbol error probability (ASEP), and ergodic channel capacity as the performance metrics in our analysis. Simulation results show the suitability of deployment of mixed RF/FSO schemes in the real-life scenarios.

Multi-User Spaceport Update News Conference

NASA Image and Video Library

2014-01-23

CAPE CANAVERAL, Fla. – Frank DiBello, right, president and CEO of Space Florida, joins Sierra Nevada Corporation, or SNC, Space Systems, as the company announces the steps it will take to prepare for a November 2016 orbital flight of its Dream Chaser spacecraft from Florida’s Space Coast. The steps are considered substantial for SNC and important to plans by NASA and Space Florida for Kennedy Space Center’s transformation into a multi-user spaceport for both commercial and government customers. SNC said it plans to work with United Launch Alliance, or ULA, to launch the Dream Chaser spacecraft into orbit atop an Atlas V rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station intends to land the winged spacecraft at Kennedy’s 3.5-mile long runway at the Shuttle Landing Facility lease office space at Exploration Park, right outside Kennedy’s gates and process the spacecraft in the high bay of the Operations and Checkout Building at Kennedy, with Lockheed Martin performing the work. Photo credit: NASA/Kim Shiflett

Multi-Use seismic stations offer strong deterrent to clandestine nuclear weapons testing

NASA Astrophysics Data System (ADS)

Hennet, C. B.; Van der Vink, G. E.; Richards, P. G.; Adushkin, V. V.; Kopnichev, Y. F.; Geary, R.

As the United States and other nations push for the signing of a Comprehensive Test Ban Treaty, representatives are meeting in Geneva this year to develop an International Seismic Monitoring System to verify compliance with the treaty's restrictions. In addition to the official monitoring system, regional networks developed for earthquake studies and basic research can provide a strong deterrent against clandestine testing. The recent release of information by the U.S. Department of Energy (DoE) on previously unannounced nuclear tests provides an opportunity to assess the ability of multi-use seismic networks to help monitor nuclear testing across the globe.Here we look at the extent to which the formerly unannounced tests were recorded and identified on the basis of publicly available seismographic data recorded by five seismic networks. The data were recorded by networks in southern Nevada and northern California at stations less than 1500 km from the Nevada Test Site (NTS), and two networks in the former Soviet Union at stations farther than 1500 km from the NTS.

Development of a web application for water resources based on open source software

NASA Astrophysics Data System (ADS)

Delipetrev, Blagoj; Jonoski, Andreja; Solomatine, Dimitri P.

2014-01-01

This article presents research and development of a prototype web application for water resources using latest advancements in Information and Communication Technologies (ICT), open source software and web GIS. The web application has three web services for: (1) managing, presenting and storing of geospatial data, (2) support of water resources modeling and (3) water resources optimization. The web application is developed using several programming languages (PhP, Ajax, JavaScript, Java), libraries (OpenLayers, JQuery) and open source software components (GeoServer, PostgreSQL, PostGIS). The presented web application has several main advantages: it is available all the time, it is accessible from everywhere, it creates a real time multi-user collaboration platform, the programing languages code and components are interoperable and designed to work in a distributed computer environment, it is flexible for adding additional components and services and, it is scalable depending on the workload. The application was successfully tested on a case study with concurrent multi-users access.

Subvisible Particle Content, Formulation, and Dose of an Erythropoietin Peptide Mimetic Product Are Associated With Severe Adverse Postmarketing Events.

PubMed

Kotarek, Joseph; Stuart, Christine; De Paoli, Silvia H; Simak, Jan; Lin, Tsai-Lien; Gao, Yamei; Ovanesov, Mikhail; Liang, Yideng; Scott, Dorothy; Brown, Janice; Bai, Yun; Metcalfe, Dean D; Marszal, Ewa; Ragheb, Jack A

2016-03-01

Peginesatide (Omontys(®); Affymax, Inc., Cupertino, CA) was voluntarily withdrawn from the market less than a year after the product launch. Although clinical trials had demonstrated the drug to be safe and efficacious, 49 cases of anaphylaxis, including 7 fatalities, were reported not long after market introduction. Commercialization was initiated with a multiuse vial presentation, which differs in formulation from the single-use vial presentation used in phase 3 studies. Standard physical and chemical testing did not indicate any deviation from product specifications in either formulation. However, an analysis of subvisible particulates using nanoparticle tracking analysis and flow imaging revealed a significantly higher concentration of subvisible particles in the multiuse vial presentation linked to the hypersensitivity cases. Although it is unknown whether the elevated particulate content is causally related to these serious adverse events, this report illustrates the utility of characterizing subvisible particulates not captured by conventional light obscuration. Copyright © 2016. Published by Elsevier Inc.

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.

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.

DWTP: a basis for networked VR on the Internet

NASA Astrophysics Data System (ADS)

Broll, Wolfgang; Schick, Daniel

1998-04-01

Shared virtual worlds are one of today's major research topics. While limited to particular application areas and high speed networks in the past, they become more and more available to a large number of users. One reason for this development was the introduction of VRML (the Virtual Reality Modeling Language), which has been established as a standard of the exchange of 3D worlds on the Internet. Although a number of prototype systems have been developed to realize shared multi-user worlds based on VRML, no suitable network protocol to support the demands of such environments has yet been established. In this paper we will introduce our approach of a network protocol for shared virtual environments: DWTP--the Distributed Worlds Transfer and communication Protocol. We will show how DWTP meets the demands of shared virtual environments on the Internet. We will further present SmallView, our prototype of a distributed multi-user VR system, to show how DWTP can be used to realize shared worlds.

47 CFR 95.1313 - Interconnection prohibited.

Code of Federal Regulations, 2010 CFR

2010-10-01

... points in the wireline or radio network of a public telephone company and persons served by multi-use... licensees or other authorized persons for transmitter control (including dial-up transmitter control circuits) or as an integral part of an authorized, private, internal system of communication or as an...

Space ALIVE!: A Multimedia-Enhanced Collaborative Learning Environment.

ERIC Educational Resources Information Center

Looi, Chee-Kit; Ang, D.

2000-01-01

Discusses online text-based collaborative learning environments such as Multi-User Dimensions (MUDs) and Object-Oriented MUDs (MOOs) and describes a multimedia-enhanced, Web-based MOO (WOO) called SpaceALIVE! that was the subject of a pilot project with Singapore secondary school students. (Contains 15 references.) (LRW)

The Maturation of Norms for Computer-Mediated Communication.

ERIC Educational Resources Information Center

Newby, Gregory B.

1993-01-01

Analyzes the communication norms of the major forms of computer-mediated communication, including electronic mail, mailing lists, Usenet and other bulletin board systems, interactive messaging, multiuser domains (MUDs), and mass-broadcast media. New uses and the development of standards, or norms, are discussed. (Contains 11 references.) (LRW)

The Changing Purposes of University Libraries

ERIC Educational Resources Information Center

Evans, G. R.

2013-01-01

This article explores recent developments in national policy for academic libraries. It considers the shift from traditional to managerial academic librarianship; the move to "social space" and multi-use systems; changes in the balance between meeting teaching and research needs and in public funding priorities; the difficulty of making…

14 CFR 417.405 - Ground safety analysis.

Code of Federal Regulations, 2013 CFR

2013-01-01

... qualified to perform the ground safety analysis through training, education, and experience. (c) A launch... unfenced boundary of an entire industrial complex or multi-user launch site. A launch location hazard may.... (j) A launch operator must verify all information in a ground safety analysis, including design...

14 CFR 417.405 - Ground safety analysis.

Code of Federal Regulations, 2014 CFR

2014-01-01

... qualified to perform the ground safety analysis through training, education, and experience. (c) A launch... unfenced boundary of an entire industrial complex or multi-user launch site. A launch location hazard may.... (j) A launch operator must verify all information in a ground safety analysis, including design...

14 CFR 417.405 - Ground safety analysis.

Code of Federal Regulations, 2012 CFR

2012-01-01

... qualified to perform the ground safety analysis through training, education, and experience. (c) A launch... unfenced boundary of an entire industrial complex or multi-user launch site. A launch location hazard may.... (j) A launch operator must verify all information in a ground safety analysis, including design...

CLEW: A Cooperative Learning Environment for the Web.

ERIC Educational Resources Information Center

Ribeiro, Marcelo Blois; Noya, Ricardo Choren; Fuks, Hugo

This paper outlines CLEW (collaborative learning environment for the Web). The project combines MUD (Multi-User Dimension), workflow, VRML (Virtual Reality Modeling Language) and educational concepts like constructivism in a learning environment where students actively participate in the learning process. The MUD shapes the environment structure.…

The integration of nutrients, cyanobacterial biomass and toxins: from a multi-use reservoir through water treatment

EPA Science Inventory

This presentation is an integrated evaluation of cyanobacterial growth and toxin production, from a reservoir through drinking water treatment - where biomass and toxin removal are achieved. Data is generated by a variety of methods: online instrumentation for chlorophyll, diss...

MOOville: The Writing Project's Own "Private Idaho".

ERIC Educational Resources Information Center

Conlon, Michael

1997-01-01

Describes how a computerized environment supplemented traditional undergraduate courses in English literature and composition at the University of Florida, and was developed with a grant from IBM. Highlights include the use of MOO (multi-user, object-oriented) space; student assignments; the client-server setting; and student and teacher…

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,…

East Fork Watershed Cooperative Meeting: Local Representatives Briefing

EPA Science Inventory

USEPA research in the East Fork of the Little Miami River Watershed takes a whole system approach to determining how to best manage water quality in this large multi-use watershed. The success of the research relies on effective partnerships with other stakeholders of water quali...

Smart Cards for Transit : Multi-Use Remotely Interrogated Stored-Data Cards for Fare and Toll Payment

DOT National Transportation Integrated Search

1995-04-01

This project developed relevant information on existing and future, stored readable/writable data card technology for fare and toll payments. The project supports the FTA objective of developing a plan for a common standard card-based fare payment sy...

A comparative analysis of high-speed rail station development into destination and multi-use facilities : the case of San Jose Diridon [summary].

DOT National Transportation Integrated Search

2017-02-01

The authors reviewed the literature on planning intermodal transit facilities, extracting recommendations about station and station-area design and land uses, operation of transportation services, and policy actions for station-area planning. They al...

A comparative analysis of high-speed rail station development into destination and multi-use facilities : the case of San Jose Diridon.

DOT National Transportation Integrated Search

2017-02-01

As a burgeoning literature on high-speed rail development indicates, good station-area planning is a very important prerequisite for the eventual successful operation of a high-speed rail station; it can also trigger opportunities for economic develo...

Resource Management in QoS-Aware Wireless Cellular Networks

ERIC Educational Resources Information Center

Zhang, Zhi

2011-01-01

Emerging broadband wireless networks that support high speed packet data with heterogeneous quality of service (QoS) requirements demand more flexible and efficient use of the scarce spectral resource. Opportunistic scheduling exploits the time-varying, location-dependent channel conditions to achieve multiuser diversity. In this work, we study…

MUVEs and Experiential Learning: Some Examples

ERIC Educational Resources Information Center

Weusijana, Baba Kofi; Svihla, Vanessa; Gawel, Drue; Bransford, John

2009-01-01

Multiuser virtual environments (MUVEs) like Second Life present unparalleled opportunities to help students connect knowledge by description to knowledge by experience; in a MUVE, students can experience phenomena rather than only reading about them. Baba Kofi Weusijana, Vanessa Svihla, Drue Gawel, and John Bransford describe their use of a maze…

The Creation of a Theoretical Framework for Avatar Creation and Revision

ERIC Educational Resources Information Center

Beck, Dennis; Murphy, Cheryl

2014-01-01

Multi-User Virtual Environments (MUVE) are increasingly being used in education and provide environments where users can manipulate minute details of their avatar's appearance including those traditionally associated with gender and race identification. The ability to choose racial and gender characteristics differs from real-world educational…

Emerging ecological datasets with application for modeling North American dust emissions

USDA-ARS?s Scientific Manuscript database

In 2011 the US Bureau of Land Management (BLM) established the Assessment, Inventory and Monitoring (AIM) program to monitor the condition of BLM land and to provide data to support evidence-based management of multi-use public lands. The monitoring program shares core data collection methods with t...

KSC-02pd0103

NASA Image and Video Library

2002-01-29

KENNEDY SPACE CENTER, FLA. -- Workers in the Vertical Processing Facility get the Large Orbital Protective Enclosure (LOPE) ready to move to the Multi-Use Lightweight Equipment (MULE) carrier. The LOPE contains part of the payload on the Hubble Space Telescope Servicing Mission, STS-109, scheduled to launch Feb. 28 from Launch Pad 39A

KSC-02pd0102

NASA Image and Video Library

2002-01-29

KENNEDY SPACE CENTER, FLA. -- Workers in the Vertical Processing Facility get the Large Orbital Protective Enclosure (LOPE) ready to move to the Multi-Use Lightweight Equipment (MULE) carrier. The LOPE contains part of the payload on the Hubble Space Telescope Servicing Mission, STS-109, scheduled to launch Feb. 28 from Launch Pad 39A

KSC-02pd0101

NASA Image and Video Library

2002-01-29

KENNEDY SPACE CENTER, FLA. -- Workers in the Vertical Processing Facility get the Large Orbital Protective Enclosure (LOPE) ready to move to the Multi-Use Lightweight Equipment (MULE) carrier. The LOPE contains part of the payload on the Hubble Space Telescope Servicing Mission, STS-109, scheduled to launch Feb. 28 from Launch Pad 39A

Teaching the Repeated Prisoner's Dilemma with a Computerized Tournament

ERIC Educational Resources Information Center

Lange, Carsten; Baylor, Amy L.

2007-01-01

The authors present a constructivist approach for teaching game theory, on the basis, in part, of Axelrod's research approach. Using the Axelrod tournament multi-user system (ATMUS) software, students create strategies for a repeated prisoner's dilemma (RPD). Later, these strategies are matched with those of their classmates' in a classroom…

Toward a Multilingual, Experiential Environment for Learning Decision Technology.

ERIC Educational Resources Information Center

Yeo, Gee Kin; Tan, Seng Teen

1999-01-01

Describes work at the National University of Singapore on the Internet in expanding a simulation game used in supporting a course in decision technology. Topics include decision support systems, multilingual support for cross-cultural decision studies, process support in a World Wide Web-enhanced multiuser domain (MUD) learning environment, and…

Speaking Personally--With John "Pathfinder" Lester

ERIC Educational Resources Information Center

Beaubois, Terry

2013-01-01

John Lester is currently the chief learning officer at ReactionGrid, a software company developing 3-D simulations and multiuser virtual world platforms. Lester's background includes working with Linden Lab on Second Life's education activities and neuroscience research. His primary focus is on collaborative learning and instructional…

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…

78 FR 72605 - Special Regulations, Areas of the National Park System, Lake Meredith National Recreation Area...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-03

... LAMR. LAMR provides some land-based recreational opportunities, such as hiking, horseback riding.... The multi-use trail will also provide additional hiking opportunities on the trail, and primitive... found in the report entitled ``Cost- Benefit and Regulatory Flexibility Analyses: Proposed Regulations...

Wiseman works with the MDCA hardware replacement, and CIR maintenance

NASA Image and Video Library

2014-09-18

ISS041-E-016781 (18 Sept. 2014) --- NASA astronaut Reid Wiseman, Expedition 41 flight engineer, works with the Multi-user Drop Combustion Apparatus (MDCA) in the Destiny laboratory of the International Space Station. The MDCA contains hardware and software to conduct unique droplet combustion experiments in space.

Computer Security Products Technology Overview

DTIC Science & Technology

1988-10-01

13 3. DATABASE MANAGEMENT SYSTEMS ................................... 15 Definition...this paper addresses fall into the areas of multi-user hosts, database management systems (DBMS), workstations, networks, guards and gateways, and...provide a portion of that protection, for example, a password scheme, a file protection mechanism, a secure database management system, or even a

Hopkins works with the MDCA hardware replacement, and CIR maintenance

NASA Image and Video Library

2013-12-31

ISS038-E-024145 (30 Dec. 2013) --- NASA astronaut Mike Hopkins, Expedition 38 flight engineer, performs in-flight maintenance on combustion research hardware in the Destiny laboratory of the International Space Station. Hopkins replaced a Multi-user Droplet Combustion Apparatus (MDCA) fuel reservoir inside the Combustion Integrated Rack (CIR).

Combustion Integration Rack (CIR)/FLame Extinguishment Experiment (FLEX)-2J Fiber Replace

NASA Image and Video Library

2015-08-20

ISS044E064666 (08/20/2015) --- NASA astronaut Kjell Lindgren replaces items inside the Multi-user Droplet Combustion Apparatus found inside the station’s Combustion Integrated Rack (CIR.) The CIR houses hardware capable of performing combustion experiments to further research of combustion in microgravity.

MEMS-Based Waste Vibrational Energy Harvesters

DTIC Science & Technology

2013-06-01

7 1. Lead Zirconium Titanate ( PZT ) .........................................................7 2. Aluminum...Laboratory PiezoMUMPS Piezoelectric Multi-User MEMS Processes PZT Lead Zirconate Titanate SEM Scanning Electron Microscopy SiO2 Silicon...titanate ( PZT ) possess high 4 coupling between the electrical and mechanical domains [11]. The output voltage, V, is related to the z-component

Tutoring and Multi-Agent Systems: Modeling from Experiences

ERIC Educational Resources Information Center

Bennane, Abdellah

2010-01-01

Tutoring systems become complex and are offering varieties of pedagogical software as course modules, exercises, simulators, systems online or offline, for single user or multi-user. This complexity motivates new forms and approaches to the design and the modelling. Studies and research in this field introduce emergent concepts that allow the…

Labyrinth, An Abstract Model for Hypermedia Applications. Description of its Static Components.

ERIC Educational Resources Information Center

Diaz, Paloma; Aedo, Ignacio; Panetsos, Fivos

1997-01-01

The model for hypermedia applications called Labyrinth allows: (1) the design of platform-independent hypermedia applications; (2) the categorization, generalization and abstraction of sparse unstructured heterogeneous information in multiple and interconnected levels; (3) the creation of personal views in multiuser hyperdocuments for both groups…

Multilevel Evaluation Systems Project. Final Report.

ERIC Educational Resources Information Center

Herman, Joan L.

Several studies were conducted in 1987 by the Multilevel Evaluation Systems Project, which focuses on developing a model for a multi-purpose, multi-user evaluation system to facilitate educational decision making and evaluation. The project model emphasizes on-going integrated assessment of individuals, classes, and programs using a variety of…

Linking Multiple Databases: Term Project Using "Sentences" DBMS.

ERIC Educational Resources Information Center

King, Ronald S.; Rainwater, Stephen B.

This paper describes a methodology for use in teaching an introductory Database Management System (DBMS) course. Students master basic database concepts through the use of a multiple component project implemented in both relational and associative data models. The associative data model is a new approach for designing multi-user, Web-enabled…

Multiple-User Microcomputer Technology and Its Application to the Library Environment.

ERIC Educational Resources Information Center

McCarthy, Cathleen D.

1987-01-01

Demonstrates the ways in which multiuser and multitasking microcomputer systems can be used for the automation of small- to medium-sized library operations. The possibilities afforded by the IBM-PC AT microcomputer are discussed and a sample configuration with estimated cost projections is provided. (EM)

Claiming Unclaimed Spaces: Virtual Spaces for Learning

ERIC Educational Resources Information Center

Miller, Nicole C.

2016-01-01

The purpose of this study was to describe and examine the environments used by teacher candidates in multi-user virtual environments. Secondary data analysis of a case study methodology was employed. Multiple data sources including interviews, surveys, observations, snapshots, course artifacts, and the researcher's journal were used in the initial…

Making Learning Fun: Quest Atlantis, A Game Without Guns

ERIC Educational Resources Information Center

Barab, Sasha; Thomas, Michael; Dodge, Tyler; Carteaux, Robert; Tuzun, Hakan

2005-01-01

This article describes the Quest Atlantis (QA) project, a learning and teaching project that employs a multiuser, virtual environment to immerse children, ages 9-12, in educational tasks. QA combines strategies used in commercial gaming environments with lessons from educational research on learning and motivation. It allows users at participating…

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)

EduMOOs: Virtual Learning Centers.

ERIC Educational Resources Information Center

Woods, Judy C.

1998-01-01

Multi-user Object Oriented Internet activities (MOOs) permit real time interaction in a text-based virtual reality via the Internet. This article explains EduMOOs (educational MOOs) and provides brief descriptions, World Wide Web addresses, and telnet addresses for selected EduMOOs. Instructions for connecting to a MOO and a list of related Web…

Three Community Building Strategies and Their Impacts in an On-Line Course.

ERIC Educational Resources Information Center

Egbert, Joy; Chao, Chin-Chi; Ngeow, Karen

This paper describes three instructional strategies designed to support community building in an online graduate teacher education course: (1) MOO (Multi-User Dimensions Object Oriented) field trips, in which participants are introduced to text-based virtual environments on the Internet through metaphoric online "field trips"; (2)…

MOOs for Teaching and Learning.

ERIC Educational Resources Information Center

Furst-Bowe, Julie

1996-01-01

Discusses the use of MOOs (Multi-User Dimension/Dungeon Object Oriented), text-based virtual reality environments, in education. Highlights include connecting to a network; exploring several MOOs to determine which is most appropriate; and familiarizing students with the MOO's interaction and behavior policies, as well as how to operate in the…

Using High Frequency Monitoring of Environmental Factors to Predict Microcystin Concentrations in a Multi-use, Inland Reservoir

EPA Science Inventory

Cyanobacteria, known as blue-green algae, are photosynthetic bacteria found naturally in marine, freshwater, and estuarine ecosystems. An increase in nutrient input and changes in the climate have contributed to the proliferation of cyanobacteria, forming harmful algal blooms, or...

Computer Viruses and Related Threats: A Management Guide.

ERIC Educational Resources Information Center

Wack, John P.; Carnahan, Lisa J.

This document contains guidance for managing the threats of computer viruses, Trojan horses, network worms, etc. and related software along with unauthorized use. It is geared towards managers of end-user groups, managers dealing with multi-user systems, personal computers, and networks. The guidance is general and addresses the vulnerabilities…

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,…

Tailored electron bunches with smooth current profiles for enhanced transformer ratios in beam-driven acceleration

DOE PAGES

Lemery, F.; Piot, P.

2015-08-03

Collinear high-gradient O(GV/m) beam-driven wakefield methods for charged-particle acceleration could be critical to the realization of compact, cost-efficient, accelerators, e.g., in support of TeV-scale lepton colliders or multiple-user free-electron laser facilities. To make these options viable, the high accelerating fields need to be complemented with large transformer ratios >2, a parameter characterizing the efficiency of the energy transfer between a wakefield-exciting “drive” bunch to an accelerated “witness” bunch. While several potential current distributions have been discussed, their practical realization appears challenging due to their often discontinuous nature. In this paper we propose several alternative continuously differentiable (smooth) current profiles whichmore » support enhanced transformer ratios. We especially demonstrate that one of the devised shapes can be implemented in a photo-emission electron source by properly shaping the photocathode-laser pulse. We finally discuss a possible superconducting linear-accelerator concept that could produce shaped drive bunches at high-repetition rates to drive a dielectric-wakefield accelerator with accelerating fields on the order of ~60 MV/m and a transformer ratio ~5 consistent with a recently proposed multiuser free-electron laser facility.« less

Tailored electron bunches with smooth current profiles for enhanced transformer ratios in beam-driven acceleration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lemery, F.; Piot, P.

Collinear high-gradient O(GV/m) beam-driven wakefield methods for charged-particle acceleration could be critical to the realization of compact, cost-efficient, accelerators, e.g., in support of TeV-scale lepton colliders or multiple-user free-electron laser facilities. To make these options viable, the high accelerating fields need to be complemented with large transformer ratios >2, a parameter characterizing the efficiency of the energy transfer between a wakefield-exciting “drive” bunch to an accelerated “witness” bunch. While several potential current distributions have been discussed, their practical realization appears challenging due to their often discontinuous nature. In this paper we propose several alternative continuously differentiable (smooth) current profiles whichmore » support enhanced transformer ratios. We especially demonstrate that one of the devised shapes can be implemented in a photo-emission electron source by properly shaping the photocathode-laser pulse. We finally discuss a possible superconducting linear-accelerator concept that could produce shaped drive bunches at high-repetition rates to drive a dielectric-wakefield accelerator with accelerating fields on the order of ~60 MV/m and a transformer ratio ~5 consistent with a recently proposed multiuser free-electron laser facility.« less

ARTEMIS: Reinvigorating History and Theory in Art and Design Education

ERIC Educational Resources Information Center

Janet, Jeff; Miles, Melissa

2009-01-01

ARTEMIS (Art Educational Multiplayer Interactive Space) is an online multi-user virtual environment that is designed around the objects, artefacts, philosophies, personalities and critical discourses of the histories and theories of art and design. Conceived as a means of reinvigorating art history and theory education in the digital age, ARTEMIS…

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…

Collaboration Modality, Cognitive Load, and Science Inquiry Learning in Virtual Inquiry Environments

ERIC Educational Resources Information Center

Erlandson, Benjamin E.; Nelson, Brian C.; Savenye, Wilhelmina C.

2010-01-01

Educational multi-user virtual environments (MUVEs) have been shown to be effective platforms for situated science inquiry curricula. While researchers find MUVEs to be supportive of collaborative scientific inquiry processes, the complex mix of multi-modal messages present in MUVEs can lead to cognitive overload, with learners unable to…

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...

A CALL for Evolving Teacher Education through 3D Microteaching

ERIC Educational Resources Information Center

Pappa, Giouli; Papadima-Sophocleous, Salomi

2016-01-01

This paper describes micro-teaching delivery in virtual worlds. Emphasis is placed on examining the effectiveness of Singularity Viewer, an Internet-based Multi-User Virtual Environment (MUVE) as the tool used for assessment of the student teacher performance. The overall goal of this endeavour lies in exploiting the opportunities derived from…

The Business Education Lab and Local Area Networking for Curriculum Improvement.

ERIC Educational Resources Information Center

Seals, Georgina; And Others

This guide explains how to incorporate a local area network (LAN) into the business education curriculum. The first section defines LAN, a communications system that links computers and other peripherals within an office or throughout nearby buildings and shares multiuser software and send and/or receive information. Curriculum planning…

A comparative analysis of high speed rail station development into destination and/or multi-use facilities : the case of San Jose Diridon.

DOT National Transportation Integrated Search

2017-02-01

As a burgeoning literature on high-speed rail development indicates, good station-area planning is a very important prerequisite for the : eventual successful operation of a high-speed rail station; it can also trigger opportunities for economic deve...

Second Life in Education: The Case of Commercial Online Virtual Reality Applied to Teaching and Learning

ERIC Educational Resources Information Center

Brown, Abbie; Sugar, William

2009-01-01

Second Life is a three-dimensional, multi-user virtual environment that has attracted particular attention for its instructional potential in professional development and higher education settings. This article describes Second Life in general and explores the benefits and challenges of using it for teaching and learning.

Clearing a Path: The 16-Bit Operating System Jungle Offers Confusion, Not Standardization.

ERIC Educational Resources Information Center

Pournelle, Jerry

1984-01-01

Discusses the design and limited uses of the Pascal, MS-DOS, CP/M, and PC-DOS operating systems as standard operating systems for 16-bit microprocessors, especially with the more sophisticated microcomputers currently being developed. Advantages and disadvantages of Unix--a multitasking, multiuser operating system--as a standard operating system…

Monitoring, Modeling, and Emergent Toxicology in the East Fork Watershed: Developing a Test Bed for Water Quality Management.

EPA Science Inventory

Overarching objectives for the development of the East Fork Watershed Test Bed in Southwestern Ohio include: 1) providing research infrastructure for integrating risk assessment and management research on the scale of a large multi-use watershed (1295 km2); 2) Focusing on process...

Collaborative Virtual Gaming Worlds in Higher Education

ERIC Educational Resources Information Center

Whitton, Nicola; Hollins, Paul

2008-01-01

There is growing interest in the use of virtual gaming worlds in education, supported by the increased use of multi-user virtual environments (MUVEs) and massively multi-player online role-playing games (MMORPGs) for collaborative learning. However, this paper argues that collaborative gaming worlds have been in use much longer and are much wider…

Collaborative Strategic Reading on Multi-Touch and Multi-User Digital Tabletop Displays

ERIC Educational Resources Information Center

Maslamani, Jaber Ali; Windeatt, Scott; Olivier, Patrick; Heslop, Phil; Kharrufa, Ahmed; Shearer, John; Balaam, Madeline

2012-01-01

This paper is part of a work-in-progress that reports on the design, development, and evaluation of a Digital Collaborative Strategic Reading (DCSR) application with regard to its effectiveness in improving English as a second language (ESL) reading comprehension. The DCSR application allows users to read collaboratively on multitouch and…

47 CFR 95.1315 - Antenna height restriction.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 5 2012-10-01 2012-10-01 false Antenna height restriction. 95.1315 Section 95... PERSONAL RADIO SERVICES Multi-Use Radio Service (MURS) General Provisions § 95.1315 Antenna height restriction. The highest point of any MURS antenna must no be more than 18.3 meters (60 feet) above the ground...

47 CFR 95.1315 - Antenna height restriction.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 5 2013-10-01 2013-10-01 false Antenna height restriction. 95.1315 Section 95... PERSONAL RADIO SERVICES Multi-Use Radio Service (MURS) General Provisions § 95.1315 Antenna height restriction. The highest point of any MURS antenna must no be more than 18.3 meters (60 feet) above the ground...

47 CFR 95.1315 - Antenna height restriction.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Antenna height restriction. 95.1315 Section 95... PERSONAL RADIO SERVICES Multi-Use Radio Service (MURS) General Provisions § 95.1315 Antenna height restriction. The highest point of any MURS antenna must no be more than 18.3 meters (60 feet) above the ground...

47 CFR 95.1315 - Antenna height restriction.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 5 2011-10-01 2011-10-01 false Antenna height restriction. 95.1315 Section 95... PERSONAL RADIO SERVICES Multi-Use Radio Service (MURS) General Provisions § 95.1315 Antenna height restriction. The highest point of any MURS antenna must no be more than 18.3 meters (60 feet) above the ground...

47 CFR 95.1315 - Antenna height restriction.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 5 2014-10-01 2014-10-01 false Antenna height restriction. 95.1315 Section 95... PERSONAL RADIO SERVICES Multi-Use Radio Service (MURS) General Provisions § 95.1315 Antenna height restriction. The highest point of any MURS antenna must no be more than 18.3 meters (60 feet) above the ground...

Remote Access to CD-ROM for the Distant Learner.

ERIC Educational Resources Information Center

Cutright, Patricia; Girrard, Kenneth M.

1991-01-01

A dial-access, multiuser, multiaccess CD-ROM search system with end-user capability was developed to provide Eastern Oregon State College distance education students with access to the information required by their studies. Based on UNIX, the system provides students with access to 12 databases, an e-mail system for messaging, interlibrary loan…

High Wired: On the Design, Use and Theory of Educational MOOs.

ERIC Educational Resources Information Center

Haynes, Cynthia, Ed.; Holmevik, Jan Rune, Ed.

MOOs (Multi-User, Object-Oriented Environments), which were designed originally as spaces for online social interaction, are increasingly recognized today for their value as educational tools. This book brings together a diverse group of experts whose contributions help answer questions and dispel myths surrounding MOOs and their use in education.…

A Virtual World Workshop Environment for Learning Agile Software Development Techniques

ERIC Educational Resources Information Center

Parsons, David; Stockdale, Rosemary

2012-01-01

Multi-User Virtual Environments (MUVEs) are the subject of increasing interest for educators and trainers. This article reports on a longitudinal project that seeks to establish a virtual agile software development workshop hosted in the Open Wonderland MUVE, designed to help learners to understand the basic principles of some core agile software…

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…

CIR fuel reservoir swap closeout

NASA Image and Video Library

2014-08-11

ISS040-E-090493 (11 Aug. 2014) --- NASA astronaut Reid Wiseman, Expedition 40 flight engineer, performs routine in-flight maintenance on the Multi-user Drop Combustion Apparatus (MDCA) inside the Combustion Integrated Rack (CIR) in the Destiny laboratory of the International Space Station. The MDCA contains hardware and software to conduct unique droplet combustion experiments in space.

CIR fuel reservoir swap closeout

NASA Image and Video Library

2014-08-11

ISS040-E-090497 (11 Aug. 2014) --- NASA astronaut Reid Wiseman, Expedition 40 flight engineer, performs routine in-flight maintenance on the Multi-user Drop Combustion Apparatus (MDCA) inside the Combustion Integrated Rack (CIR) in the Destiny laboratory of the International Space Station. The MDCA contains hardware and software to conduct unique droplet combustion experiments in space.

CIR fuel reservoir swap closeout

NASA Image and Video Library

2014-08-11

ISS040-E-090482 (11 Aug. 2014) --- NASA astronaut Reid Wiseman, Expedition 40 flight engineer, performs routine in-flight maintenance on the Multi-user Drop Combustion Apparatus (MDCA) inside the Combustion Integrated Rack (CIR) in the Destiny laboratory of the International Space Station. The MDCA contains hardware and software to conduct unique droplet combustion experiments in space.

CIR fuel reservoir swap closeout

NASA Image and Video Library

2014-08-11

ISS040-E-090484 (11 Aug. 2014) --- NASA astronaut Reid Wiseman, Expedition 40 flight engineer, performs routine in-flight maintenance on the Multi-user Drop Combustion Apparatus (MDCA) inside the Combustion Integrated Rack (CIR) in the Destiny laboratory of the International Space Station. The MDCA contains hardware and software to conduct unique droplet combustion experiments in space.

13 Tips for Virtual World Teaching

ERIC Educational Resources Information Center

Villano, Matt

2008-01-01

Multi-user virtual environments (MUVEs) are gaining momentum as the latest and greatest learning tool in the world of education technology. How does one get started with them? How do they work? This article shares 13 secrets from immersive education experts and educators on how to have success in implementing these new tools and technologies on…

Interaction Management Strategies on IRC and Virtual Chat Rooms.

ERIC Educational Resources Information Center

Altun, Arif

Internet Relay Chat (IRC) is an electronic medium that combines orthographic form with real time, synchronous transmission in an unregulated global multi-user environment. The orthographic letters mediate the interaction in that users can only access the IRC session through reading and writing; they have no access to any visual representations at…

Cabana Multi-User Spaceport Tour of KSC

NASA Image and Video Library

2017-02-17

Inside Boeing’s Commercial Crew and Cargo Processing Facility at NASA's Kennedy Space Center in Florida members of the news media view work platforms that will be used in manufacturing Boeing's CST-100 Starliner spacecraft for flight tests and crew rotation missions to the International Space Station as part of the agency's Commercial Crew Program.

Electronic Discourses in a Graduate Seminar: MOO Conferences as Liminal Discursive Spaces.

ERIC Educational Resources Information Center

Rouzie, Albert

Power relations between professors and graduate students are fluid, in many ways under continuous negotiation. This is especially true in electronically mediated interchanges. Although a professor's power and authority far from disappear in a MOO (multi-user object-oriented domain) session, the power and influence of the students rise to challenge…

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…

Full Moon with Vehicle Assembly Building and Mobile Launcher

NASA Image and Video Library

2018-02-01

A full Moon sets behind the Vehicle Assembly Building and Mobile Launcher at NASA’s Kennedy Space Center in Florida. At the nation’s premier multi-user spaceport, NASA and its commercial and international partners are looking to return humans to the Moon and beyond utilizing a variety of rockets and capabilities.

MOOving around the Net: The Educational Potential of MOOs.

ERIC Educational Resources Information Center

1996

The use of MOOs, multi-user simulated environments in education examined in three papers include: "MOOving around the Net: The Educational Potential of MOOs: A Point of View" (Daniel Ingvarson); "MOOing in a Foreign Language: How, Why and Who?" (Lonnie Turbee) and "MOOving around the Net: Real to Virtual and Back…

Programming for Fun: MUDs as a Context for Collaborative Learning.

ERIC Educational Resources Information Center

Bruckman, Amy

Multi-User Dungeons (MUDs), are text-based virtual reality environments in which participants separated by great physical distances can communicate and collaborate in programming. Most MUDs started out as adventure games but are quickly being adapted for more "serious" endeavors. This paper presents a case study of the experiences of a…

EdMOO: One Approach to a Multimedia Collaborative Environment.

ERIC Educational Resources Information Center

Holkner, Bernard

The nature of the multiuser object oriented (MOO) environment lends itself to flexible and rich interactive collaboration space providing interactive discussion, mail, mailing list, and news features to its virtual denizens. EdMOO (HREF1) was created in mid-1995 as an environment for teachers to experience the text based virtual reality…

A Theoretical Cybernetic Macro-Script to Articulate Collaborative Interactions of Cyber Entities in Virtual Worlds

ERIC Educational Resources Information Center

Pellas, Nikolaos

2014-01-01

Nowadays, the dissemination and exploitation of three-dimensional (3D) multi-user virtual worlds in higher education have been disclosed from their widespread acceptance as candidate learning platforms. However, it is still lacking a theoretical cybernetic macro-script to elaborate the coordination of multiple complex interactions among…

Don't Play It, Make It!

ERIC Educational Resources Information Center

O'Hanlon, Charlene

2011-01-01

Using games as a learning tool is not new--research abounds to demonstrate the use of video games enhancing problem-solving skills and creativity. Pioneer educational games, like Carmen Sandiego and Oregon Trail, have given birth to online, multiuser, digital simulations that would make their forebears blush. Now, in what seems to be a natural…

ACHP | Working Together to Build a More Inclusive Preservation Program

Science.gov Websites

Working with Section 106 Federal, State, & Tribal Programs Training & Education Publications should serve as a museum of one period in time but as a laboratory of its transformation over the years transformation of Cleveland's downtown from a singularly business-centric to a multi-use live/work/play

The Composition of Dramatic Experience: The Play Element in Student Electronic Projects.

ERIC Educational Resources Information Center

Rouzie, Albert

2000-01-01

Analyzes two student group Hypertext projects and a MOO (multiuser domain, object-oriented) project. Finds the play element can enrich readerly experience through the creation of a dramatic experience of information. Suggests that composition instructors need to recognize the play element in computer-based composition and encourage the development…

"Mooving" to a Virtual Curriculum.

ERIC Educational Resources Information Center

LaRoe, R. John

Three writing classes at the University of Missouri (freshman, sophomore, and senior) spent much or most of the semester on the virtual campus of the Diversity University (DU) MOO (multi-user object oriented). The freshman class wrote one paper on Internet exploration, another on their favorite Internet destination, and for the third were given a…

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…

On Being Bored and Lost (in Virtuality)

ERIC Educational Resources Information Center

Moore, Kristen; Pflugfelder, Ehren Helmut

2010-01-01

Education in virtual worlds has the potential, it seems, for engaging students in innovative ways and for enabling new discourses on a host of issues. Virtual locations like "Second Life," "Kaneva," or "World of Warcraft," among other multi-user virtual environments (MUVEs), also come with unique challenges for educators as they consider the…

Mobile-IT Education (MIT.EDU): M-Learning Applications for Classroom Settings

ERIC Educational Resources Information Center

Sung, M.; Gips, J.; Eagle, N.; Madan, A.; Caneel, R.; DeVaul, R.; Bonsen, J.; Pentland, A.

2005-01-01

In this paper, we describe the Mobile-IT Education (MIT.EDU) system, which demonstrates the potential of using a distributed mobile device architecture for rapid prototyping of wireless mobile multi-user applications for use in classroom settings. MIT.EDU is a stable, accessible system that combines inexpensive, commodity hardware, a flexible…

An Investigation into Cooperative Learning in a Virtual World Using Problem-Based Learning

ERIC Educational Resources Information Center

Parson, Vanessa; Bignell, Simon

2017-01-01

Three-dimensional multi-user virtual environments (MUVEs) have the potential to provide experiential learning qualitatively similar to that found in the real world. MUVEs offer a pedagogically-driven immersive learning opportunity for educationalists that is cost-effective and enjoyable. A family of digital virtual avatars was created within…

Walk, Fly, or Teleport to Learning: Virtual Worlds in the Classroom

ERIC Educational Resources Information Center

Yoder, Maureen Brown

2009-01-01

For educators looking for new ways to engage their students, multiuser virtual environments (MUVEs) offer a great opportunity for creative teaching and learning. MUVEs teach students social, technical, and practical life skills in a setting that is engaging and playful. One might be surprised how much these virtual environments teach students…

Teaching with Virtual Worlds: Factors to Consider for Instructional Use of Second Life

ERIC Educational Resources Information Center

Mayrath, Michael C.; Traphagan, Tomoko; Jarmon, Leslie; Trivedi, Avani; Resta, Paul

2010-01-01

Substantial evidence now supports pedagogical applications of virtual worlds; however, most research supporting virtual worlds for education has been conducted using researcher-developed Multi-User Virtual Environments (MUVE). Second Life (SL) is a MUVE that has been adopted by a large number of academic institutions; however, little research has…

On the Integration of Remote Experimentation into Undergraduate Laboratories--Pedagogical Approach

ERIC Educational Resources Information Center

Esche, Sven K.

2005-01-01

This paper presents an Internet-based open approach to laboratory instruction. In this article, the author talks about an open laboratory approach using a multi-user multi-device remote facility. This approach involves both the direct contact with the computer-controlled laboratory setup of interest with the students present in the laboratory…

Multi-User Spaceport Update News Conference

NASA Image and Video Library

2014-01-23

CAPE CANAVERAL, Fla. – Larry Price, Lockheed Martin Space Systems deputy program manager for NASA's Orion spacecraft, joins Sierra Nevada Corporation, or SNC, Space Systems, as the company announces the steps it will take to prepare for a November 2016 orbital flight of its Dream Chaser spacecraft from Florida’s Space Coast. The steps are considered substantial for SNC and important to plans by NASA and Space Florida for Kennedy Space Center’s transformation into a multi-user spaceport for both commercial and government customers. SNC said it plans to work with United Launch Alliance, or ULA, to launch the Dream Chaser spacecraft into orbit atop an Atlas V rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station intends to land the winged spacecraft at Kennedy’s 3.5-mile long runway at the Shuttle Landing Facility lease office space at Exploration Park, right outside Kennedy’s gates and process the spacecraft in the high bay of the Operations and Checkout Building at Kennedy, with Lockheed Martin performing the work. Photo credit: NASA/Kim Shiflett

[Waste management in hospitals. Current situation in the state of North Rhine-Westphalia].

PubMed

Popp, W; Hansen, D; Hilgenhöner, M; Grandek, M; Heinemann, A; Blättler, T

2009-07-01

In 20 hospitals in North Rhine-Westphalia in-plant handling wastes and the delivery of the waste to the disposer were examined. Deficits were seen regarding risk assessment and operating instructions, support by company doctors, personal protection equipment, and break areas for the waste collecting personnel. Also the qualification of the waste management officer and his/her time contingent, correct declaration of the wastes, the training of the waste collecting personnel, the cleaning of multi-use containers and transportation vehicles, storage of the wastes at the collecting points, and the use of sharp collecting boxes were to be partly criticized. Consequences and recommendations are given, concerning the company's obligations (e.g., provide risk assessment, operating instructions), waste management officer (e.g., qualification, enough time contingent, regular inspections), waste collecting personnel (e.g., training courses), industrial safety (e.g., protection equipment, break area wash places), company doctors, transportation vehicles in the house (e.g., regular cleaning), one-way collectors (e.g., labelling at the site of the collection), multi-use collectors (e.g., cleaning), and compressing containers (e.g., larger maintenance openings).

Multi-user distribution of polarization entangled photon pairs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trapateau, J.; Orieux, A.; Diamanti, E.

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 themore » 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.« less

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.

Performance Analysis of Physical Layer Security of Opportunistic Scheduling in Multiuser Multirelay Cooperative Networks

PubMed Central

Shim, Kyusung; Do, Nhu Tri; An, Beongku

2017-01-01

In this paper, we study the physical layer security (PLS) of opportunistic scheduling for uplink scenarios of multiuser multirelay cooperative networks. To this end, we propose a low-complexity, yet comparable secrecy performance source relay selection scheme, called the proposed source relay selection (PSRS) scheme. Specifically, the PSRS scheme first selects the least vulnerable source and then selects the relay that maximizes the system secrecy capacity for the given selected source. Additionally, the maximal ratio combining (MRC) technique and the selection combining (SC) technique are considered at the eavesdropper, respectively. Investigating the system performance in terms of secrecy outage probability (SOP), closed-form expressions of the SOP are derived. The developed analysis is corroborated through Monte Carlo simulation. Numerical results show that the PSRS scheme significantly improves the secure ability of the system compared to that of the random source relay selection scheme, but does not outperform the optimal joint source relay selection (OJSRS) scheme. However, the PSRS scheme drastically reduces the required amount of channel state information (CSI) estimations compared to that required by the OJSRS scheme, specially in dense cooperative networks. PMID:28212286

Efficiently Multi-User Searchable Encryption Scheme with Attribute Revocation and Grant for Cloud Storage

PubMed Central

Wang, Shangping; Zhang, Xiaoxue; Zhang, Yaling

2016-01-01

Cipher-policy attribute-based encryption (CP-ABE) focus on the problem of access control, and keyword-based searchable encryption scheme focus on the problem of finding the files that the user interested in the cloud storage quickly. To design a searchable and attribute-based encryption scheme is a new challenge. In this paper, we propose an efficiently multi-user searchable attribute-based encryption scheme with attribute revocation and grant for cloud storage. In the new scheme the attribute revocation and grant processes of users are delegated to proxy server. Our scheme supports multi attribute are revoked and granted simultaneously. Moreover, the keyword searchable function is achieved in our proposed scheme. The security of our proposed scheme is reduced to the bilinear Diffie-Hellman (BDH) assumption. Furthermore, the scheme is proven to be secure under the security model of indistinguishability against selective ciphertext-policy and chosen plaintext attack (IND-sCP-CPA). And our scheme is also of semantic security under indistinguishability against chosen keyword attack (IND-CKA) in the random oracle model. PMID:27898703

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.

Efficiently Multi-User Searchable Encryption Scheme with Attribute Revocation and Grant for Cloud Storage.

PubMed

Wang, Shangping; Zhang, Xiaoxue; Zhang, Yaling

2016-01-01

Cipher-policy attribute-based encryption (CP-ABE) focus on the problem of access control, and keyword-based searchable encryption scheme focus on the problem of finding the files that the user interested in the cloud storage quickly. To design a searchable and attribute-based encryption scheme is a new challenge. In this paper, we propose an efficiently multi-user searchable attribute-based encryption scheme with attribute revocation and grant for cloud storage. In the new scheme the attribute revocation and grant processes of users are delegated to proxy server. Our scheme supports multi attribute are revoked and granted simultaneously. Moreover, the keyword searchable function is achieved in our proposed scheme. The security of our proposed scheme is reduced to the bilinear Diffie-Hellman (BDH) assumption. Furthermore, the scheme is proven to be secure under the security model of indistinguishability against selective ciphertext-policy and chosen plaintext attack (IND-sCP-CPA). And our scheme is also of semantic security under indistinguishability against chosen keyword attack (IND-CKA) in the random oracle model.

Effectiveness of Strict vs. Multiple Use Protected Areas in Reducing Tropical Forest Fires: A Global Analysis Using Matching Methods

PubMed Central

Nelson, Andrew; Chomitz, Kenneth M.

2011-01-01

Protected areas (PAs) cover a quarter of the tropical forest estate. Yet there is debate over the effectiveness of PAs in reducing deforestation, especially when local people have rights to use the forest. A key analytic problem is the likely placement of PAs on marginal lands with low pressure for deforestation, biasing comparisons between protected and unprotected areas. Using matching techniques to control for this bias, this paper analyzes the global tropical forest biome using forest fires as a high resolution proxy for deforestation; disaggregates impacts by remoteness, a proxy for deforestation pressure; and compares strictly protected vs. multiple use PAs vs indigenous areas. Fire activity was overlaid on a 1 km map of tropical forest extent in 2000; land use change was inferred for any point experiencing one or more fires. Sampled points in pre-2000 PAs were matched with randomly selected never-protected points in the same country. Matching criteria included distance to road network, distance to major cities, elevation and slope, and rainfall. In Latin America and Asia, strict PAs substantially reduced fire incidence, but multi-use PAs were even more effective. In Latin America, where there is data on indigenous areas, these areas reduce forest fire incidence by 16 percentage points, over two and a half times as much as naïve (unmatched) comparison with unprotected areas would suggest. In Africa, more recently established strict PAs appear to be effective, but multi-use tropical forest protected areas yield few sample points, and their impacts are not robustly estimated. These results suggest that forest protection can contribute both to biodiversity conservation and CO2 mitigation goals, with particular relevance to the REDD agenda. Encouragingly, indigenous areas and multi-use protected areas can help to accomplish these goals, suggesting some compatibility between global environmental goals and support for local livelihoods. PMID:21857950

Effects of Spearfishing on Reef Fish Populations in a Multi-Use Conservation Area

PubMed Central

Frisch, Ashley J.; Cole, Andrew J.; Hobbs, Jean-Paul A.; Rizzari, Justin R.; Munkres, Katherine P.

2012-01-01

Although spearfishing is a popular method of capturing fish, its ecological effects on fish populations are poorly understood, which makes it difficult to assess the legitimacy and desirability of spearfishing in multi-use marine reserves. Recent management changes within the Great Barrier Reef Marine Park (GBRMP) fortuitously created a unique scenario by which to quantify the effects of spearfishing on fish populations. As such, we employed underwater visual surveys and a before-after-control-impact experimental design to investigate the effects of spearfishing on the density and size structure of target and non-target fishes in a multi-use conservation park zone (CPZ) within the GBRMP. Three years after spearfishing was first allowed in the CPZ, there was a 54% reduction in density and a 27% reduction in mean size of coral trout (Plectropomus spp.), the primary target species. These changes were attributed to spearfishing because benthic habitat characteristics and the density of non-target fishes were stable through time, and the density and mean size of coral trout in a nearby control zone (where spearfishing was prohibited) remained unchanged. We conclude that spearfishing, like other forms of fishing, can have rapid and substantial negative effects on target fish populations. Careful management of spearfishing is therefore needed to ensure that conservation obligations are achieved and that fishery resources are harvested sustainably. This is particularly important both for the GBRMP, due to its extraordinarily high conservation value and world heritage status, and for tropical island nations where people depend on spearfishing for food and income. To minimize the effects of spearfishing on target species and to enhance protection of functionally important fishes (herbivores), we recommend that fishery managers adjust output controls such as size- and catch-limits, rather than prohibit spearfishing altogether. This will preserve the cultural and social importance of spearfishing in coastal communities where it is practised. PMID:23251656

Simultaneous polarization-insensitive phase-space trans-multiplexing and wavelength multicasting via cross-phase modulation in a photonic crystal fiber at 10 GBd

NASA Astrophysics Data System (ADS)

Cannon, Brice M.

This thesis investigates the all-optical combination of amplitude and phase modulated signals into one unified multi-level phase modulated signal, utilizing the Kerr nonlinearity of cross-phase modulation (XPM). Predominantly, the first experimental demonstration of simultaneous polarization-insensitive phase-transmultiplexing and multicasting (PI-PTMM) will be discussed. The PI-PTMM operation combines the data of a single 10-Gbaud carrier-suppressed return-to-zero (CSRZ) on-off keyed (OOK) pump signal and 4x10-Gbaud return-to-zero (RZ) binary phase-shift keyed (BPSK) probe signals to generate 4x10-GBd RZ-quadrature phase-shift keyed (QPSK) signals utilizing a highly nonlinear, birefringent photonic crystal fiber (PCF). Since XPM is a highly polarization dependent nonlinearity, a polarization sensitivity reduction technique was used to alleviate the fluctuations due to the remotely generated signals' unpredictable states of polarization (SOP). The measured amplified spontaneous emission (ASE) limited receiver sensitivity optical signal-to-noise ratio (OSNR) penalty of the PI-PTMM signal relative to the field-programmable gate array (FPGA) pre-coded RZ-DQPSK baseline at a forward-error correction (FEC) limit of 10-3 BER was ≈ 0.3 dB. In addition, the OSNR of the remotely generated CSRZ-OOK signal could be degraded to ≈ 29 dB/0.1nm, before the bit error rate (BER) performance of the PI-PTMM operation began to exponentially degrade. A 138-km dispersion-managed recirculating loop system with a 100-GHz, 13-channel mixed-format dense-wavelength-division multiplexed (DWDM) transmitter was constructed to investigate the effect of metro/long-haul transmission impairments. The PI-PTMM DQPSK and the FPGA pre-coded RZ-DQPSK baseline signals were transmitted 1,900 km and 2,400 km in the nonlinearity-limited transmission regime before reaching the 10-3 BER FEC limit. The relative reduction in transmission distance for the PI-PTMM signal was due to the additional transmitter impairments in the PCF that interact negatively with the transmission fiber.

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…

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…

Hopkins works with the MDCA inside the CIR in the U.S. Laboratory

NASA Image and Video Library

2013-11-12

ISS038-E-001298 (12 Nov. 2013) --- NASA astronaut Michael Hopkins, Expedition 38 flight engineer, works with the Multi-user Drop Combustion Apparatus (MDCA) inside the Combustion Integrated Rack (CIR) in the Destiny laboratory of the International Space Station. The MDCA contains hardware and software to conduct unique droplet combustion experiments in space.

A Proposed Theory Seeded Methodology for Design Based Research into Effective Use of MUVES in Vocational Education Contexts

ERIC Educational Resources Information Center

Cochrane, Todd; Davis, Niki; Morrow, Donna

2013-01-01

A methodology for design based research (DBR) into effective development and use of Multi-User Virtual Environments (MUVE) in vocational education is proposed. It blends software development with DBR with two theories selected to inform the methodology. Legitimate peripheral participation LPP (Lave & Wenger, 1991) provides a filter when…

An Intelligent Crawler for a Virtual World

ERIC Educational Resources Information Center

Eno, Joshua

2010-01-01

Virtual worlds, which allow users to create and interact with content in a 3D, multi-user environment, growing and becoming more integrated with the traditional flat web. However, little is empirically known about the content users create in virtual world and how it can be indexed and searched effectively. In order to gain a better understanding…

An Examination of Usability of a Virtual Environment for Students Enrolled in a College of Agriculture

ERIC Educational Resources Information Center

Murphrey, Theresa Pesl; Rutherford, Tracy A.; Doerfert, David L.; Edgar, Leslie D.; Edgar, Don W.

2014-01-01

Educational technology continues to expand with multi-user virtual environments (e.g., Second Life™) being the latest technology. Understanding a virtual environment's usability can enhance educational planning and effective use. Usability includes the interaction quality between an individual and the item being assessed. The purpose was to assess…

Shifts in Student Motivation during Usage of a Multi-User Virtual Environment for Ecosystem Science

ERIC Educational Resources Information Center

Metcalf, Shari; Chen, Jason; Kamarainen, Amy; Frumin, Kim; Vickrey, Trisha; Grotzer, Tina; Dede, Chris

2014-01-01

In incorporating technology in science education, some have expressed concern that the value added by technology is primarily due to the novelty or excitement about using the devices, resulting in no lasting effect on student motivation or learning in science. This research addresses this concern through evaluation of student motivation during a…

Adaptive, Tactical Mesh Networking: Control Base MANET Model

DTIC Science & Technology

2010-09-01

pp. 316–320 Available: IEEE Xplore , http://ieeexplore.ieee.org [Accessed: June 9, 2010]. [5] N. Sidiropoulos, “Multiuser Transmit Beamforming...Mobile Mesh Segments of TNT Testbed .......... 11 Figure 5. Infrastructure and Ad Hoc Mode of IEEE 802.11................................ 13 Figure...6. The Power Spectral Density of OFDM................................................ 14 Figure 7. A Typical IEEE 802.16 Network

Adoption of Second Life in Higher Education: Comparing the Effect of Utilitarian and Hedonic Behaviours

ERIC Educational Resources Information Center

Saeed, Nauman; Sinnappan, Sukunesan

2013-01-01

Second Life is a three dimensional multi-user virtual environment within the Web 2.0 suite of applications which has gained wide spread popularity amongst educators in the recent years. However, limited empirical research has been reported on the adoption of Second Life, especially within higher education. The majority of technology adoption…

Enhance Learning on Software Project Management through a Role-Play Game in a Virtual World

ERIC Educational Resources Information Center

Maratou, Vicky; Chatzidaki, Eleni; Xenos, Michalis

2016-01-01

This article presents a role-play game for software project management (SPM) in a three-dimensional online multiuser virtual world. The Opensimulator platform is used for the creation of an immersive virtual environment that facilitates students' collaboration and realistic interaction, in order to manage unexpected events occurring during the…

Efficient multiuser quantum cryptography network based on entanglement.

PubMed

Xue, Peng; Wang, Kunkun; Wang, Xiaoping

2017-04-04

We present an efficient quantum key distribution protocol with a certain entangled state to solve a special cryptographic task. Also, we provide a proof of security of this protocol by generalizing the proof of modified of Lo-Chau scheme. Based on this two-user scheme, a quantum cryptography network protocol is proposed without any quantum memory.

Efficient multiuser quantum cryptography network based on entanglement

PubMed Central

Xue, Peng; Wang, Kunkun; Wang, Xiaoping

2017-01-01

We present an efficient quantum key distribution protocol with a certain entangled state to solve a special cryptographic task. Also, we provide a proof of security of this protocol by generalizing the proof of modified of Lo-Chau scheme. Based on this two-user scheme, a quantum cryptography network protocol is proposed without any quantum memory. PMID:28374854

3-Dimensional and Interactive Istanbul University Virtual Laboratory Based on Active Learning Methods

ERIC Educational Resources Information Center

Ince, Elif; Kirbaslar, Fatma Gulay; Yolcu, Ergun; Aslan, Ayse Esra; Kayacan, Zeynep Cigdem; Alkan Olsson, Johanna; Akbasli, Ayse Ceylan; Aytekin, Mesut; Bauer, Thomas; Charalambis, Dimitris; Gunes, Zeliha Ozsoy; Kandemir, Ceyhan; Sari, Umit; Turkoglu, Suleyman; Yaman, Yavuz; Yolcu, Ozgu

2014-01-01

The purpose of this study is to develop a 3-dimensional interactive multi-user and multi-admin IUVIRLAB featuring active learning methods and techniques for university students and to introduce the Virtual Laboratory of Istanbul University and to show effects of IUVIRLAB on students' attitudes on communication skills and IUVIRLAB. Although there…

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…

MOO: Using a Computer Gaming Environment to Teach about Community Arts

ERIC Educational Resources Information Center

Garber, Elizabeth

2004-01-01

In this paper, the author discusses the use of an interactive computer technology, "MOO" (Multi-user domain, Object-Oriented), in her art education classes for preservice teachers. A MOO is a text-based environment wherein interactivity is centered on text exchanges made between users based on problems or other materials created by teachers. The…

Definition of avionics concepts for a heavy lift cargo vehicle, appendix A

NASA Technical Reports Server (NTRS)

1989-01-01

The major objective of the study task was to define a cost effective, multiuser simulation, test, and demonstration facility to support the development of avionics systems for future space vehicles. This volume provides the results of the main simulation processor selection study and describes some proof-of-concept demonstrations for the avionics test bed facility.

77 FR 40547 - Special Regulations; Areas of the National Park System, Chattahoochee River National Recreation...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-10

... acres of park land, including riverside units and upland forested areas with hiking trails and other... final trail plan has 3 miles of hiking-only trails and 6.7 miles of multi-use trails allowing both... purposes. This certification is based on the cost-benefit and regulatory flexibility analysis found in the...

Using "Second Life" in School Librarianship

ERIC Educational Resources Information Center

Perez, Lisa

2009-01-01

In this article, the author discusses using Second Life (SL) in school librarianship. SL is a multi-user virtual environment in which persons create avatars to allow them to move and interact with other avatars. They can build and manipulate objects. To move, they can walk, run, fly, or teleport. There are many areas within SL to allow people to…

High Frequency monitoring of cyanoHABs and cyanotoxin production to characterize periods of greatest risk on an inland reservoir

EPA Science Inventory

A monitoring approach combining wet chemistry and high frequency (HF) water quality sensors has been employed to improve our understanding of the ecology of an inland reservoir with a history of cyanoHAB events. Lake Harsha is a multi-use reservoir managed by the USACE in southwe...

KSC-2014-3531

NASA Image and Video Library

2014-08-14

CAPE CANAVERAL, Fla. – A thunderstorm moving through NASA’s Kennedy Space Center in Florida approaches Launch Pad 39B, in the distance. Kennedy's Ground Support Development and Operations Program is hard at work transforming the center's facilities into a multi-user spaceport, when the weather permits. For more on Kennedy Space Center, visit http://www.nasa.gov/kennedy. Photo credit: NASA/Ben Smegelsky

KSC-2013-1528

NASA Image and Video Library

2013-02-15

CAPE CANAVERAL, Fla. – An artist's concept shows a possible layout of a commercial spacecraft and rocket using facilities at Launch Pad 39A as NASA's Kennedy Space Center in Florida undergoes a transformation into a multi-user spaceport. Several companies are designing rockets and spacecraft that could be used to launch astronauts and payloads into space in the future. Credit: NASA

Kelly with CIR

NASA Image and Video Library

2010-10-26

ISS025-E-009308 (26 Oct. 2010) --- NASA astronaut Scott Kelly, Expedition 25 flight engineer, works on the Combustion Integrated Rack (CIR) Multi-user Drop Combustion Apparatus (MDCA) in the Destiny laboratory of the International Space Station. Kelly set up an experiment run on the Fluids & Combustion Facility (FCF) with a new fuel reservoir, ground-assisted by Payload Operations Integration Center/Huntsville (POIC).

MDCA Needle 1 Replacement

NASA Image and Video Library

2013-04-22

ISS035-E-025557(22 April 2013) ---Multi-user Droplet Combustion Apparatus (MDCA) Hardware Replacement: Cassidy accessed the Combustion Integration Rack (CIR) Combustion Chamber and removed the MDCA Chamber Insert Assembly (CIA). He then replaced the MDCA Needle 1 due to a fuel line that was damaged during previous activities when the MDCA CIA was being removed from the Combustion Chamber.

Composition and development of reproduction in two-age Appalachian hardwood stands: 20-year results

Treesearch

Gary W. Miller; James N. Kochenderfer; Desta Fekedulegn

2004-01-01

In the early 1980s, silviculturists with the Northeastern Research Station and Monongahela National Forest envisioned that managing some Appalachian hardwood stands to promote two-age structures would be part of an effective strategy for managing multi-use forests. Two-age stands provided the light and seedbed conditions necessary for regenerating numerous desirable...

Designing for Real-World Scientific Inquiry in Virtual Environments

ERIC Educational Resources Information Center

Ketelhut, Diane Jass; Nelson, Brian C.

2010-01-01

Background: Most policy doctrines promote the use of scientific inquiry in the K-12 classroom, but good inquiry is hard to implement, particularly for schools with fiscal and safety constraints and for teachers struggling with understanding how to do so. Purpose: In this paper, we present the design of a multi-user virtual environment (MUVE)…

Pollution control: utility ships adapt for spill cleanups

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1986-02-01

A practical and cost effective approach to oil spill cleanup is being undertaken by Dutch companies. The approach involves constructing and equipping multi-use ships for pollution control. Usually, these ships are maintained in another type of service and come into use for spill cleanup only when needed. The use of these ships in pollution control is discussed.

MURI: Impact of Oceanographic Variability on Acoustic Communications

DTIC Science & Technology

2011-09-01

multiplexing ( OFDM ), multiple- input/multiple-output ( MIMO ) transmissions, and multi-user single-input/multiple-output (SIMO) communications. Lastly... MIMO - OFDM communications: Receiver design for Doppler distorted underwater acoustic channels,” Proc. Asilomar Conf. on Signals, Systems, and... MIMO ) will be of particular interest. Validating experimental data will be obtained during the ONR acoustic communications experiment in summer 2008

Efficient multiuser quantum cryptography network based on entanglement

NASA Astrophysics Data System (ADS)

Xue, Peng; Wang, Kunkun; Wang, Xiaoping

2017-04-01

We present an efficient quantum key distribution protocol with a certain entangled state to solve a special cryptographic task. Also, we provide a proof of security of this protocol by generalizing the proof of modified of Lo-Chau scheme. Based on this two-user scheme, a quantum cryptography network protocol is proposed without any quantum memory.

Avatars Go to Class: A Virtual Environment Soil Science Activity

ERIC Educational Resources Information Center

Mamo, M.; Namuth-Covert, D.; Guru, A.; Nugent, G.; Phillips, L.; Sandall, L.; Kettler, T.; McCallister, D.

2011-01-01

Web 2.0 technology is expanding rapidly from social and gaming uses into the educational applications. Specifically, the multi-user virtual environment (MUVE), such as SecondLife, allows educators to fill the gap of first-hand experience by creating simulated realistic evolving problems/games. In a pilot study, a team of educators at the…

Learning Outcome, Presence and Satisfaction from a Science Activity in Second Life

ERIC Educational Resources Information Center

Vrellis, Ioannis; Avouris, Nikolaos; Mikropoulos, Tassos A.

2016-01-01

Although problem-based learning (PBL) has many advantages, it often fails to connect to the real world outside the classroom. The integration with the laboratory setting and the use of information and communication technologies (ICTs) have been proposed to address this deficiency. Multi-user virtual environments (MUVEs) like Second Life (SL) are…

Affordances and Limitations of Immersive Participatory Augmented Reality Simulations for Teaching and Learning

ERIC Educational Resources Information Center

Dunleavy, Matt; Dede, Chris; Mitchell, Rebecca

2009-01-01

The purpose of this study was to document how teachers and students describe and comprehend the ways in which participating in an augmented reality (AR) simulation aids or hinders teaching and learning. Like the multi-user virtual environment (MUVE) interface that underlies Internet games, AR is a good medium for immersive collaborative…

E-Drama: Facilitating Online Role-Play Using an AI Actor and Emotionally Expressive Characters

ERIC Educational Resources Information Center

Zhang, Li; Gillies, Marco; Dhaliwal, Kulwant; Gower, Amanda; Robertson, Dale; Crabtree, Barry

2009-01-01

This paper describes a multi-user role-playing environment, referred to as "e-drama", which enables groups of people to converse online, in scenario driven virtual environments. The starting point of this research, is an existing application known as "edrama", a 2D graphical environment in which users are represented by static…

Gaming in Second Life via Scratch4SL: Engaging High School Students in Programming Courses

ERIC Educational Resources Information Center

Pellas, Nikolaos; Peroutseas, Efstratios

2016-01-01

While pedagogical and technological affordances of three-dimensional (3D) multiuser virtual worlds in various educational disciplines are largely well-known, a study about their effect on high school students' engagement in introductory programming courses is still lacking. This case study presents students' opinions about their participation in a…

Actualizing the Environment: A Study of First-Year Composition Student MOO Activity.

ERIC Educational Resources Information Center

English, Joel A.

This paper describes the use of technology in a first year college writing class. The class utilizes a multi-user object-oriented domain (MOO) which allows participants to talk, perform actions, thoughts, and emotions, manipulate objects and furniture, and altogether control the online environment. The class holds discussions on the computer in…

EFL Learner Collaborative Interaction in Second Life

ERIC Educational Resources Information Center

Peterson, Mark

2012-01-01

This paper reports on the task-based interaction of English as a Foreign Language (EFL) learners in the 3D multiuser virtual environment (MUVE) Second Life. The discussion first explores research on the precursors of MUVEs, text-based 2D virtual worlds known as MOOs. This is followed by an examination of studies on the use of MUVEs in Computer…

Design, Fabrication, and Characterization of a Microelectromechanical Directional Microphone

DTIC Science & Technology

2011-06-01

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES...Figure 5.2 SOIC packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Figure 5.3 Laboratory setup...Mean Squared SOC System-On-Chip SOIC Small Outline Integrated Circuit SOIMUMPS Silicon-On-Insulator Multi-User MEMS Process SPL Sound Pressure Level

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…

Role Play in Blended Learning: A Case Study Exploring the Impact of Story and Other Elements

ERIC Educational Resources Information Center

Dracup, Mary

2008-01-01

Role play is an increasingly popular technique in tertiary education, being student centred, constructivist and suitable for a range of subject areas. The choice of formats is wide open, with options ranging from the traditional face to face performance through to multi-user online computer games. Some teachers prefer to take advantage of features…

Using CODAP Job Analysis for the Development of Integrated Training Requirements for Three Army Civilian Career Fields.

ERIC Educational Resources Information Center

Fisher, Gerald P.; And Others

A multiuse Comprehensive Occupational Data Analysis Program (CODAP) job analysis is being used to develop training requirements and selection criteria for three interrelated Army civilian logistics career fields. Individual job task lists for the 20 job series within the three career programs were developed. The lists were based on a review of…

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…

Touring Mars Online, Real-time, in 3D for Math and Science Educators and Students

ERIC Educational Resources Information Center

Jones, Greg; Kalinowski, Kevin

2007-01-01

This article discusses a project that placed over 97% of Mars' topography made available from NASA into an interactive 3D multi-user online learning environment beginning in 2003. In 2005 curriculum materials that were created to support middle school math and science education were developed. Research conducted at the University of North Texas…

Four Season Programming for Ecological Stewardship

ERIC Educational Resources Information Center

Krelove, Katie

2008-01-01

As a nature interpreter who has had the pleasure to teach, learn from, and explore with many people of all ages, it is clear to this author that these young people represent among the best hope for the future of a valuable natural place in the heart of the City of Toronto that is constantly threatened--High Park. The park is multi-use: one can…

Using Activity Theory to Understand Intergenerational Play: The Case of Family Quest

ERIC Educational Resources Information Center

Siyahhan, Sinem; Barab, Sasha A.; Downton, Michael P.

2010-01-01

We implemented a five-week family program called "Family Quest" where parents and children ages 9 to 13 played Quest Atlantis, a multiuser 3D educational computer game, at a local after-school club for 90-minute sessions. We used activity theory as a conceptual and an analytical framework to study the nature of intergenerational play, the…

The Effectiveness of Web-Based Foreign Exchange Trading Simulation in an International Finance Course

ERIC Educational Resources Information Center

Chou, Chen-Huei; Liu, Hao-Chen

2013-01-01

The purpose of this article is to study if trading simulation is an effective tool to increase students' knowledge of the foreign exchange market. We developed a real-time multiuser web-based trading system that replicates an electronic brokerage foreign exchange market. To assess the effectiveness of the program, we conducted surveys in three…

Design Concerns in the Engineering of Virtual Worlds for Learning

ERIC Educational Resources Information Center

Rapanotti, Lucia; Hall, Jon G.

2011-01-01

The convergence of 3D simulation and social networking into current multi-user virtual environments has opened the door to new forms of interaction for learning in order to complement the face-to-face and Web 2.0-based systems. Yet, despite a growing user community, design knowledge for virtual worlds remains patchy, particularly when it comes to…

A Look inside a MUVE Design Process: Blending Instructional Design and Game Principles to Target Writing Skills

ERIC Educational Resources Information Center

Warren, Scott J.; Stein, Richard A.; Dondlinger, Mary Jo; Barab, Sasha A.

2009-01-01

The number of games, simulations, and multi-user virtual environments designed to promote learning, engagement with subject matter, or intended to contextualize learning has been steadily increasing over the past decade. While the use of these digital designs in educational settings has begun to show promise for improving learning, motivation, and…

Teachers and Game-Based Learning: Improving Understanding of How to Increase Efficacy of Adoption

ERIC Educational Resources Information Center

Ketelhut, Diane Jass; Schifter, Catherine C.

2011-01-01

Interest in game-based learning for K-12 is growing. Thus, helping teachers understand how to use these new pedagogies is important. This paper presents a cross-case study of the development of teacher professional development for the River City project, a games-based multi-user virtual environment science curriculum project for middle school…

Vice President Mike Pence Speech at Vehicle Assembly Building

NASA Image and Video Library

2017-07-06

Vice President Mike Pence got a first-hand look at the public-private partnerships at America’s multi-user spaceport on Thursday, July 6, during a visit to NASA’s Kennedy Space Center in Florida. Speaking in the center’s iconic Vehicle Assembly Building, the Vice President thanked employees for their commitment to America’s continued leadership in the space frontier.

Real-Life Migrants on the MUVE: Stories of Virtual Transitions

ERIC Educational Resources Information Center

Perkins, Ross A.; Arreguin, Cathy

2007-01-01

The communication and collaborative interface known as a multi-user virtual environment (MUVE), has existed since as early as the late 1970s. MUVEs refer to programs that have an animated character ("avatar") controlled by a user within a wider environment that can be explored--or built--at will. Second Life, a MUVE created by San Francisco-based…

Teaching an Aerospace Engineering Design Course via Virtual Worlds: A Comparative Assessment of Learning Outcomes

ERIC Educational Resources Information Center

Okutsu, Masataka; DeLaurentis, Daniel; Brophy, Sean; Lambert, Jason

2013-01-01

To test the concept of multiuser 3D virtual environments as media to teach semester-long courses, we developed a software prototype called Aeroquest. An aerospace design course--offered to 135 second-year students for university credits in Fall 2009--was divided into two groups: the real-world group attending lectures, physically, in a campus hall…

A Multi-Modal Digital Game-Based Learning Environment for Hospitalized Children with Chronic Illnesses.

ERIC Educational Resources Information Center

Chin, Jui-Chih; Tsuei, Mengping

2014-01-01

The aim of this study was to explore the digital game-based learning for children with chronic illnesses in the hospital settings. The design-based research and qualitative methods were applied. Three eight-year-old children with leukemia participated in this study. In the first phase, the multi-user game-based learning system was developed and…

A Design for a Multi-Use Object Editor with Connections

DTIC Science & Technology

1991-10-01

Variables of Class Select 14 3.6.2 Methods of Class Select 14 3.6.3 Application States 14 3.7 Class Clipboard 15 3.8 Class Crestore 15 3.9 Conclusions 15 4...this is not directly related to cutting and past- ing between applications. 3.8 CLASS CRESTORE Class crestore holds a connection until all the

MOO in Your Face: Researching, Designing, and Programming a User-Friendly Interface.

ERIC Educational Resources Information Center

Haas, Mark; Gardner, Clinton

1999-01-01

Suggests the learning curve of a multi-user, object-oriented domain (MOO) blockades effective use. Discusses use of an IBM/PC-compatible interface that allows developers to modify the interface to provide a sense of presence for the user. Concludes that work in programming a variety of interfaces has led to a more intuitive environment for…

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…

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…

Design and test of a regenerative satellite transmultiplexer

NASA Astrophysics Data System (ADS)

Hung, Kenny King-Ming

1993-05-01

In a multiple access scheme for regenerative satellite communications, the bulk frequency division multiple access (FDMA) uplink signal is demodulated on board the satellite and then remodulated for time division multiplexing (TDM) downlink transmission. Conversion from frequency to time division multiplex format requires that the uplink signal be frequency demultiplexed and each individual carrier be subsequently demodulated. For thin-route application which consists of a large number of channels with fixed data rate, multicarrier demodulation can be accomplished efficiently by a digital transmultiplexer (TMUX) using a fast Fourier transform processor followed by a bank of per-channel processors. A time domain description of the TMUX algorithm is derived which elucidates how the TMUX functions. The per-channel processor performs timing and carrier recovery for optimum and coherent data detection. Timing recovery is necessarily achieved asynchronously by a filter coefficient interpolation. Carrier recovery is performed using an all-digital phase-locked loop. The combination of both timing and carrier loops is investigated for a multi-user system. The performance of the overall system is assessed over a multi-user, additive white Gaussian noise channel for a bit energy to noise power spectral density ratio down to zero dB.

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.

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.

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.

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

PubMed Central

ANDERSON, JR; MOHAMMED, S; GRIMM, B; JONES, BW; KOSHEVOY, P; TASDIZEN, T; WHITAKER, R; MARC, RE

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

Monitoring environmental impact in the Upper Sonoran Lifestyle: a new tool for rapid ecological assessment.

PubMed

Allen, Casey D

2009-02-01

Characterized by expensive housing, high socioeconomic status, and topographic relief, Upper Sonoran Lifestyle communities are found primarily along the Wildland-Urban Interface (WUI) in the Phoenix, Arizona metro area. Communities like these sprawl into the wildlands in the United States Southwest, creating a distinct urban fringe. This article, through locational comparison, introduces and evaluates a new field assessment tool for monitoring anthropogenic impact on soil-vegetation interactions along the well-maintained multi-use recreational trails in Upper Sonoran Lifestyle region. Comparing data from randomly selected transects along other multi-use trails with data from a control site revealed three key indicators of anthropogenic disturbances on soil-vegetation interactions: soil disturbance, vegetation disturbance, and vegetation density. Soil and vegetation disturbance displayed an average distance decay exponent factor of -0.60, while vegetation density displayed a reverse decay average of 0.60. Other important indicators of disturbance included vegetation type, biological soil crusts, and soil bulk density. The predictive ability of this new field tool enhances its applicability, offering a powerful rapid ecological assessment method for monitoring long-term anthropogenic impact in the Upper Sonoran Lifestyle, and other sprawling cities along the WUI.

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.

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

Multi-user quantum key distribution with entangled photons from an AlGaAs chip

NASA Astrophysics Data System (ADS)

Autebert, C.; Trapateau, J.; Orieux, A.; Lemaître, A.; Gomez-Carbonell, C.; Diamanti, E.; Zaquine, I.; Ducci, S.

2016-12-01

In view of real-world applications of quantum information technologies, the combination of miniature quantum resources with existing fibre networks is a crucial issue. Among such resources, on-chip entangled photon sources play a central role for applications spanning quantum communications, computing and metrology. Here, we use a semiconductor source of entangled photons operating at room temperature in conjunction with standard telecom components to demonstrate multi-user quantum key distribution, a core protocol for securing communications in quantum networks. The source consists of an AlGaAs chip-emitting polarisation entangled photon pairs over a large bandwidth in the main telecom band around 1550 nm without the use of any off-chip compensation or interferometric scheme; the photon pairs are directly launched into a dense wavelength division multiplexer (DWDM) and secret keys are distributed between several pairs of users communicating through different channels. We achieve a visibility measured after the DWDM of 87% and show long-distance key distribution using a 50-km standard telecom fibre link between two network users. These results illustrate a promising route to practical, resource-efficient implementations adapted to quantum network infrastructures.

Built Environment Influences of Children's Physical Activity: Examining Differences by Neighbourhood Size and Sex.

PubMed

Mitchell, Christine A; Clark, Andrew F; Gilliland, Jason A

2016-01-15

Neighbourhoods can facilitate or constrain moderate-to-vigorous physical activity (MVPA) among children by providing or restricting opportunities for MVPA. However, there is no consensus on how to define a child's neighbourhood. This study examines the influence of the neighbourhood built environment on objectively measured MVPA among 435 children (aged 9-14 years) in London (ON, Canada). As there is no consensus on how to delineate a child's neighbourhood, a geographic information system was used to generate measures of the neighbourhood built environment at two buffer sizes (500 m and 800 m) around each child's home. Linear regression models with robust standard errors (cluster) were used to analyze the relationship between built environment characteristics and average daily MVPA during non-school hours on weekdays. Sex-stratified models assessed sex-specific relationships. When accounting for individual and neighbourhood socio-demographic variables, park space and multi-use path space were found to influence children's MVPA. Sex-stratified models found significant associations between MVPA and park space, with the 800 m buffer best explaining boys' MVPA and the 500 m buffer best explaining girls' MVPA. Findings emphasize that, when designing built environments, programs, and policies to facilitate physical activity, it is important to consider that the size of the neighbourhood influencing a child's physical activity may differ according to sex.

Open Sim and Sloodle Integration for Preservice Foreign Language Teachers' Continuing Professional Development: A Comparative Analysis of Learning Effectiveness Using the Community of Inquiry Model

ERIC Educational Resources Information Center

Pellas, Nikolaos; Boumpa, Anna

2016-01-01

A considerable interest in using three-dimensional multi-user virtual worlds for different educational disciplines has been widely observed. Despite the potential benefits of this technology, many questions still remain open, as far as the design of appropriate activities in well-defined instructional design frameworks and their effectiveness on…

Acceptance of Cloud Services in Face-to-Face Computer-Supported Collaborative Learning: A Comparison between Single-User Mode and Multi-User Mode

ERIC Educational Resources Information Center

Wang, Chia-Sui; Huang, Yong-Ming

2016-01-01

Face-to-face computer-supported collaborative learning (CSCL) was used extensively to facilitate learning in classrooms. Cloud services not only allow a single user to edit a document, but they also enable multiple users to simultaneously edit a shared document. However, few researchers have compared student acceptance of such services in…

Educational Game as Supplemental Learning Tool: Benefits, Challenges, and Tensions Arising from Use in an Elementary School Classroom

ERIC Educational Resources Information Center

Warren, Scott; Dondlinger, Mary Jo; Stein, Richard; Barab, Sasha

2009-01-01

This article examines the qualitative findings from a mixed-methods comparison study of the use of an online multi-user virtual environment called Anytown which supplemented face-to-face writing instruction in a fourth grade classroom to determine implications for the design of such environments and the reported impact of this design on students…

Vice President Mike Pence Visits Kennedy Space Center

NASA Image and Video Library

2017-07-06

Vice President Mike Pence arrives at the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida. During his visit, Pence spoke inside the iconic building, where he thanked employees for advancing American leadership in space. The Vice President also toured several facilities highlighting the public-private partnerships at Kennedy, as both NASA and commercial companies prepare to launch American astronauts from the multi-user spaceport.

An Activity Theoretical Perspective towards the Design of an ICT-Enhanced After-School Programme for Academically At-Risk Students

ERIC Educational Resources Information Center

Tay, Lee Yong; Lim, Cher Ping

2010-01-01

This paper examines how a game-like 3D Multi-User Virtual Environment (MUVE), Quest Atlantis (QA), is used in an after-school programme to engage a group of 14 academically at-risk primary students in their learning. It adopts an activity theoretical perspective to identify the disturbances and contradictions during the implementation of the…

Exploring the Effects of Integrating Self-Explanation into a Multi-User Game on the Acquisition of Scientific Concepts

ERIC Educational Resources Information Center

Hsu, Chung-Yuan; Tsai, Chin-Chung; Wang, Hung-Yuan

2016-01-01

The purpose of this study was to examine the impacts of embedding collaboration into a game with a self-explanation design for supporting the acquisition of light and shadow concepts. The participants were 184 fourth graders who were randomly assigned to three conditions: a solitary mode of the game with self-explanation, a collaborative mode with…

Multiuser Transmit Beamforming for Maximum Sum Capacity in Tactical Wireless Multicast Networks

DTIC Science & Technology

2006-08-01

commonly used extended Kalman filter . See [2, 5, 6] for recent tutorial overviews. In particle filtering , continuous distributions are approximated by...signals (using and developing associated particle filtering tools). Our work on these topics has been reported in seven (IEEE, SIAM) journal papers and...multidimensional scaling, tracking, intercept, particle filters . 16. PRICE CODE 17. SECURITY CLASSIFICATION OF REPORT 18. SECURITY CLASSIFICATION OF

The Role of the Ion Microprobe in Solid-Earth Geochemistry

NASA Astrophysics Data System (ADS)

Hauri, E. H.

2002-12-01

Despite the early success of the electron microprobe in taking petrology to the micron scale, and the widespread use of mass spectrometers in geochemistry and geochronology, it was not until the mid-1970s that the ion microprobe came into its own as an in situ analytical tool in the Earth sciences. Despite this inauspicious beginning, secondary ion mass spectrometry (SIMS) was widely advertised as a technology that would eventually eclipse thermal ion mass spectrometry (TIMS) in isotope geology. However this was not to happen. While various technical issues in SIMS such as interferences and matrix effects became increasingly clear, an appreciation grew for the complimentary abilities of SIMS and TIMS that, even with the advent of ICP-MS, continues to this day. Today the ion microprobe is capable of abundance measurements in the parts-per-billion range across nearly the entire periodic table, and SIMS stable isotope data quality is now routinely crossing the 1 per mil threshold, all at the micron scale. Much of this success is due to the existence of multi-user community facilities for SIMS research, and the substantial efforts of interested scientists to understand the fundamentals of sputtered ion formation and their application to geochemistry. Recent discoveries of evidence for the existence of ancient crust and oceans, the emergence of life on Earth, the large-scale cycling of surficial materials into the deep Earth, and illumination of fundamental high-pressure phenomena have all been made possible by SIMS, and these (and many more) discoveries owe a debt to the vision of creating and supporting multi-user community facilities for SIMS. The ion microprobe remains an expensive instrument to purchase and maintain, yet it is also exceedingly diverse in application. Major improvements in SIMS, indeed in all mass spectrometry, are visible on the near horizon. Yet the geochemical community cannot depend on commercial manufacturers alone to design and build the next generation of instrumentation for geochemistry. Such will be the role of instrument-minded scientists asking questions that simply cannot be answered by extant means. And it will be multi-user facilities that will make such advancements available to the wider geochemical community.

Integrated all-optical programmable logic array based on semiconductor optical amplifiers.

PubMed

Dong, Wenchan; Huang, Zhuyang; Hou, Jie; Santos, Rui; Zhang, Xinliang

2018-05-01

The all-optical programmable logic array (PLA) is one of the most important optical complex logic devices that can implement combinational logic functions. In this Letter, we propose and experimentally demonstrate an integrated all-optical PLA at the operation speed of 40 Gb/s. The PLA mainly consists of a delay interferometer (DI) and semiconductor optical amplifiers (SOAs) of different lengths. The DI is used to pre-code the input signals and improve the reconfigurability of the scheme. The longer SOAs are nonlinear media for generating canonical logic units (CLUs) using four-wave mixing. The shorter SOAs are used to select the appropriate CLUs by changing the working states; then reconfigurable logic functions can be output directly. The results show that all the CLUs are realized successfully, and the optical signal-to-noise ratios are above 22 dB. The exclusive NOR gate and exclusive OR gate are experimentally demonstrated based on output CLUs.

Optimal threshold of error decision related to non-uniform phase distribution QAM signals generated from MZM based on OCS

NASA Astrophysics Data System (ADS)

Han, Xifeng; Zhou, Wen

2018-03-01

Optical vector radio-frequency (RF) signal generation based on optical carrier suppression (OCS) in one Mach-Zehnder modulator (MZM) can realize frequency-doubling. In order to match the phase or amplitude of the recovered quadrature amplitude modulation (QAM) signal, phase or amplitude pre-coding is necessary in the transmitter side. The detected QAM signals usually have one non-uniform phase distribution after square-law detection at the photodiode because of the imperfect characteristics of the optical and electrical devices. We propose to use optimal threshold of error decision for non-uniform phase contribution to reduce the bit error rate (BER). By employing this scheme, the BER of 16 Gbaud (32 Gbit/s) quadrature-phase-shift-keying (QPSK) millimeter wave signal at 36 GHz is improved from 1 × 10-3 to 1 × 10-4 at - 4 . 6 dBm input power into the photodiode.

Very Large-Scale Multiuser Detection (VLSMUD)

DTIC Science & Technology

2006-09-01

networks: A market -based approach,” IEEE/ACM Transactions on Networking, vol. 13, no. 6, pp. 1325– 1338, December 2005. [5] F. Meshkati, H. V. Poor, S . C... s / / s / DAVID HENCH WARREN H. DEBANY, Jr. Work Unit Manager Technical Advisor, Information Grid Division...5e. TASK NUMBER UD 6. AUTHOR( S ) H. Vincent Poor 5f. WORK UNIT NUMBER 01 7. PERFORMING ORGANIZATION NAME( S ) AND ADDRESS(ES) Princeton

Detailed Design and Implementation of a Multiprogramming Operating System for Sixteen-Bit Microprocessors.

DTIC Science & Technology

1983-12-01

4 Multiuser Support ...... .......... 11-5 User Interface . .. .. ................ .. 11- 7 Inter -user Communications ................ 11- 7 Memory...user will greatly help facilitate the learning process. Inter -User Communication The inter -user communications of the operating system can be done using... inter -user communications would be met by using one or both of them. AMemory and File Management Memory and file management is concerned with four basic

Learning in 3-D Multiuser Virtual Environments: Exploring the Use of Unique 3-D Attributes for Online Problem-Based Learning

ERIC Educational Resources Information Center

Omale, Nicholas; Hung, Wei-Chen; Luetkehans, Lara; Cooke-Plagwitz, Jessamine

2009-01-01

The purpose of this article is to present the results of a study conducted to investigate how the attributes of 3-D technology such as avatars, 3-D space, and comic style bubble dialogue boxes affect participants' social, cognitive, and teaching presences in a blended problem-based learning environment. The community of inquiry model was adopted…

The Use of a UNIX-Based Workstation in the Information Systems Laboratory

DTIC Science & Technology

1989-03-01

system. The conclusions of the research and the resulting recommendations are presented in Chapter III. These recommendations include how to manage...required to run the program on a new system, these should not be significant changes. 2. Processing Environment The UNIX processing environment is...interactive with multi-tasking and multi-user capabilities. Multi-tasking refers to the fact that many programs can be run concurrently. This capability

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…

Extreme C2 and Multi-Touch, Multi-User Collaborative User Interfaces

DTIC Science & Technology

2008-06-01

Organization: Office of the Chief Engineer , Space and Naval Warfare Systems Center Charleston Address: PO Box 190022 N. Charleston, SC 29419 843...collaborative development technique can increase the adaptability and quality of software, something of high value in the complex domain of enterprise...concept to C2 should be able to produce similar benefits for planning in military operations, particularly complex, multi- faceted operations. This

KSC-2014-3529

NASA Image and Video Library

2014-08-14

CAPE CANAVERAL, Fla. – This view from the NASA Press Site parking lot captures storm clouds approaching Launch Pad 39B, in the distance at right, at NASA’s Kennedy Space Center in Florida. Kennedy's Ground Support Development and Operations Program is hard at work transforming the center's facilities into a multi-user spaceport, when the weather permits. For more on Kennedy Space Center, visit http://www.nasa.gov/kennedy. Photo credit: NASA/Ben Smegelsky

Space-Time Processing for Tactical Mobile Ad Hoc Networks

DTIC Science & Technology

2007-08-01

rates in mobile ad hoc networks. In addition, he has considered the design of a cross-layer multi-user resource allocation framework using a... framework for many-to-one communication. In this context, multiple nodes cooperate to transmit their packets simultaneously to a single node using multi...spatially multiplexed signals transmitted from multiple nodes. Our goal is to form a framework that activates different sets of communication links

Computer-Based Instruction (CBI): Considerations for a User-Oriented Technology Data Base.

DTIC Science & Technology

1985-10-14

CBI works primarily because of the systematic attention to instructional material it brings to the development process , and the extent to which quality...looked at CBI software multi-use potential, support and maintenance from a joint service perspective, and described requirements for a software...computer support for some aspect of the instructional process . Personnel involved in other TDAC projects are reviewing commercially available CBI and

Advancing Underwater Acoustic Communication for Autonomous Distributed Networks via Sparse Channel Sensing, Coding, and Navigation Support

DTIC Science & Technology

2012-09-30

Estimation Methods for Underwater OFDM 5) Two Iterative Receivers for Distributed MIMO - OFDM with Large Doppler Deviations. 6) Asynchronous Multiuser...multi-input multi-output ( MIMO ) OFDM is also pursued, where it is shown that the proposed hybrid initialization enables drastically improved receiver...are investigated. 5) Two Iterative Receivers for Distributed MIMO - OFDM with Large Doppler Deviations. This work studies a distributed system with

Developing the Systems Engineering Experience Accelerator (SEEA) Prototype and Roadmap

DTIC Science & Technology

2013-12-31

information to be automatically presented without comment. 2.2.2 NEW FEATURES AND CAPABILITIES A number of new multiplayer capabilities were...2.4.1 OVERVIEW The EA game engine has two components: the runtime engine and the tools suite. The tools suite includes the Experience Development...the Learner. Figure 6: Experience Accelerator Logical Block Diagram The EARTE is a multiuser architecture for internet gaming . It has light

Power adaptive multi-filter carrierless amplitude and phase access scheme for visible light communication network

NASA Astrophysics Data System (ADS)

Li, Wei; Huang, Zhitong; Li, Haoyue; Ji, Yuefeng

2018-04-01

Visible light communication (VLC) is a promising candidate for short-range broadband access due to its integration of advantages for both optical communication and wireless communication, whereas multi-user access is a key problem because of the intra-cell and inter-cell interferences. In addition, the non-flat channel effect results in higher losses for users in high frequency bands, which leads to unfair qualities. To solve those issues, we propose a power adaptive multi-filter carrierless amplitude and phase access (PA-MF-CAPA) scheme, and in the first step of this scheme, the MF-CAPA scheme utilizing multiple filters as different CAP dimensions is used to realize multi-user access. The character of orthogonality among the filters in different dimensions can mitigate the effect of intra-cell and inter-cell interferences. Moreover, the MF-CAPA scheme provides different channels modulated on the same frequency bands, which further increases the transmission rate. Then, the power adaptive procedure based on MF-CAPA scheme is presented to realize quality fairness. As demonstrated in our experiments, the MF-CAPA scheme yields an improved throughput compared with multi-band CAP access scheme, and the PA-MF-CAPA scheme enhances the quality fairness and further improves the throughput compared with the MF-CAPA scheme.

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.

The bacterial contamination rate of glucose meter test strips in the hospital setting

PubMed Central

Al-Rubeaan, Khalid A.; Saeb, Amr T. M.; AlNaqeb, Dhekra M.; AlQumaidi, Hamed M.; AlMogbel, Turki A.

2016-01-01

Objectives: To assess the rate of bacterial contamination of the multi-use vial and single-use packed glucose meter strips, and to identify the type and frequency of various bacterial contamination in different hospital wards. Methods: This prospective observational study was conducted by a team from the Strategic Center for Diabetes Research in 7 general hospitals in the Central region of Saudi Arabia during the period from August to September 2014 to assess the bacterial contamination rate of the unused strips. A total of 10,447 strips were cultured using proper agar media and incubated both aerobically and anaerobically. Results: The total bacterial contamination rate for the multi-use vials glucose strips was 31.7%, while single-use packed strips were not contaminated at all. Ministry of Health hospitals had the highest contamination rates compared with other hospitals. Critical, obstetric, and surgical wards had the highest bacterial isolates number, where most were in the risk group 3 according to the National Institute of Health guidelines. Staphylococcus species were the most common bacteria found. Conclusion: Glucose meter strips should be recognized as a source of bacterial contamination that could be behind serious hospital acquired infections. The hospital infection control team should adopt proper measures to implement protocols for glucose meter cleaning and glucose strips handling. PMID:27570855

Transition in the Human Exploration of Space at NASA

NASA Technical Reports Server (NTRS)

Koch, Carla A.; Cabana, Robert

2011-01-01

NASA is taking the next step in human exploration, beyond low Earth orbit. We have been going to low Earth orbit for the past 50 years and are using this experience to work with commercial companies to perform this function. This will free NASA resources to develop the systems necessary to travel to a Near Earth Asteroid, the Moon, Lagrange Points, and eventually Mars. At KSC, we are positioning ourselves to become a multi-user launch complex and everything we are working on is bringing us closer to achieving this goal. A vibrant multi-use spaceport is to the 21st Century what the airport was to the 20th Century - an invaluable transportation hub that supports government needs while promoting economic development and commercial markets beyond Earth's atmosphere. This past year saw the end of Shuttle, but the announcements of NASA's crew module, Orion, and heavy-lift rocket, the SLS, as well as the establishment of the Commercial Crew Program. We have a busy, but very bright future ahead of us and KSC is looking forward to playing an integral part in the next era of human space exploration. The future is SLS, 21st Century Ground Systems Program, and the Commercial Crew Program; and the future is here.

Performance Analysis of a De-correlated Modified Code Tracking Loop for Synchronous DS-CDMA System under Multiuser Environment

NASA Astrophysics Data System (ADS)

Wu, Ya-Ting; Wong, Wai-Ki; Leung, Shu-Hung; Zhu, Yue-Sheng

This paper presents the performance analysis of a De-correlated Modified Code Tracking Loop (D-MCTL) for synchronous direct-sequence code-division multiple-access (DS-CDMA) systems under multiuser environment. Previous studies have shown that the imbalance of multiple access interference (MAI) in the time lead and time lag portions of the signal causes tracking bias or instability problem in the traditional correlating tracking loop like delay lock loop (DLL) or modified code tracking loop (MCTL). In this paper, we exploit the de-correlating technique to combat the MAI at the on-time code position of the MCTL. Unlike applying the same technique to DLL which requires an extensive search algorithm to compensate the noise imbalance which may introduce small tracking bias under low signal-to-noise ratio (SNR), the proposed D-MCTL has much lower computational complexity and exhibits zero tracking bias for the whole range of SNR, regardless of the number of interfering users. Furthermore, performance analysis and simulations based on Gold codes show that the proposed scheme has better mean square tracking error, mean-time-to-lose-lock and near-far resistance than the other tracking schemes, including traditional DLL (T-DLL), traditional MCTL (T-MCTL) and modified de-correlated DLL (MD-DLL).

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. © 2010 The Authors Journal of Microscopy © 2010 The Royal Microscopical Society.

Mediated definite delegation - Certified Grid jobs in ALICE and beyond

NASA Astrophysics Data System (ADS)

Schreiner, Steffen; Grigoras, Costin; Litmaath, Maarten; Betev, Latchezar; Buchmann, Johannes

2012-12-01

Grid computing infrastructures need to provide traceability and accounting of their users’ activity and protection against misuse and privilege escalation, where the delegation of privileges in the course of a job submission is a key concern. This work describes an improved handling of Multi-user Grid Jobs in the ALICE Grid Services. A security analysis of the ALICE Grid job model is presented with derived security objectives, followed by a discussion of existing approaches of unrestricted delegation based on X.509 proxy certificates and the Grid middleware gLExec. Unrestricted delegation has severe security consequences and limitations, most importantly allowing for identity theft and forgery of jobs and data. These limitations are discussed and formulated, both in general and with respect to an adoption in line with Multi-user Grid Jobs. A new general model of mediated definite delegation is developed, allowing a broker to dynamically process and assign Grid jobs to agents while providing strong accountability and long-term traceability. A prototype implementation allowing for fully certified Grid jobs is presented as well as a potential interaction with gLExec. The achieved improvements regarding system security, malicious job exploitation, identity protection, and accountability are emphasized, including a discussion of non-repudiation in the face of malicious Grid jobs.

A cooperative transponder system for improved traffic safety, localizing road users in the 5 GHz band

NASA Astrophysics Data System (ADS)

Schaffer, B.; Kalverkamp, G.; Chaabane, M.; Biebl, E. M.

2012-09-01

We present a multi-user cooperative mobile transponder system which enables cars to localize pedestrians, bicyclists and other road users in order to improve traffic safety. The system operates at a center frequency of 5.768 GHz, offering the ability to test precision localization technology at frequencies close to the newly designated automotive safety related bands around 5.9 GHz. By carrying out a roundtrip time of flight measurement, the sensor can determine the distance from the onboard localization unit of a car to a road user who is equipped with an active transponder, employing the idea of a secondary radar and pulse compression. The onboard unit sends out a pseudo noise coded interrogation pulse, which is answered by one or more transponders after a short waiting time. Each transponder uses a different waiting time in order to allow for time division multiple access. We present the system setup as well as range measurement results, achieving an accuracy up to centimeters for the distance measurement and a range in the order of hundred meters. We also discuss the effect of clock drift and offset on distance accuracy for different waiting times and show how the system can be improved to further increase precision in a multiuser environment.

Sparsity-Cognizant Algorithms with Applications to Communications, Signal Processing, and the Smart Grid

NASA Astrophysics Data System (ADS)

Zhu, Hao

Sparsity plays an instrumental role in a plethora of scientific fields, including statistical inference for variable selection, parsimonious signal representations, and solving under-determined systems of linear equations - what has led to the ground-breaking result of compressive sampling (CS). This Thesis leverages exciting ideas of sparse signal reconstruction to develop sparsity-cognizant algorithms, and analyze their performance. The vision is to devise tools exploiting the 'right' form of sparsity for the 'right' application domain of multiuser communication systems, array signal processing systems, and the emerging challenges in the smart power grid. Two important power system monitoring tasks are addressed first by capitalizing on the hidden sparsity. To robustify power system state estimation, a sparse outlier model is leveraged to capture the possible corruption in every datum, while the problem nonconvexity due to nonlinear measurements is handled using the semidefinite relaxation technique. Different from existing iterative methods, the proposed algorithm approximates well the global optimum regardless of the initialization. In addition, for enhanced situational awareness, a novel sparse overcomplete representation is introduced to capture (possibly multiple) line outages, and develop real-time algorithms for solving the combinatorially complex identification problem. The proposed algorithms exhibit near-optimal performance while incurring only linear complexity in the number of lines, which makes it possible to quickly bring contingencies to attention. This Thesis also accounts for two basic issues in CS, namely fully-perturbed models and the finite alphabet property. The sparse total least-squares (S-TLS) approach is proposed to furnish CS algorithms for fully-perturbed linear models, leading to statistically optimal and computationally efficient solvers. The S-TLS framework is well motivated for grid-based sensing applications and exhibits higher accuracy than existing sparse algorithms. On the other hand, exploiting the finite alphabet of unknown signals emerges naturally in communication systems, along with sparsity coming from the low activity of each user. Compared to approaches only accounting for either one of the two, joint exploitation of both leads to statistically optimal detectors with improved error performance.

Activity Recognition for Personal Time Management

NASA Astrophysics Data System (ADS)

Prekopcsák, Zoltán; Soha, Sugárka; Henk, Tamás; Gáspár-Papanek, Csaba

We describe an accelerometer based activity recognition system for mobile phones with a special focus on personal time management. We compare several data mining algorithms for the automatic recognition task in the case of single user and multiuser scenario, and improve accuracy with heuristics and advanced data mining methods. The results show that daily activities can be recognized with high accuracy and the integration with the RescueTime software can give good insights for personal time management.

An Optimization of the Basic School Military Occupational Skill Assignment Process

DTIC Science & Technology

2003-06-01

Corps Intranet (NMCI)23 supports it. We evaluated the use of Microsoft’s SQL Server, but dismissed this after learning that TBS did not possess a SQL ...Server license or a qualified SQL Server administrator.24 SQL Server would have provided for additional security measures not available in MS...administrator. Although not has powerful as SQL Server, MS Access can handle the multi-user environment necessary for this system.25 The training

EVAL system concept definition. Partial spacelab payload

NASA Technical Reports Server (NTRS)

1976-01-01

The preliminary design of an earth-viewing spacelab payload, with accommodations shared by both NASA and ESA is addressed. Mission parameters for this flight include a launch date of September 1981, an inclination of 57 deg, and an orbital altitude of 325 km. A seven-day mission is planned. The NASA portion of this payload is assigned to the EVAL (Earth Viewing Applications Laboratory) program. The ESA complement is designed as a multiuser payload.

Tactical Operations Analysis Support Facility.

DTIC Science & Technology

1981-05-01

Punch/Reader 2 DMC-11AR DDCMP Micro Processor 2 DMC-11DA Network Link Line Unit 2 DL-11E Async Serial Line Interface 4 Intel IN-1670 448K Words MOS Memory...86 5.3 VIRTUAL PROCESSORS - VAX-11/750 ........................... 89 5.4 A RELATIONAL DATA MANAGEMENT SYSTEM - ORACLE...Central Processing Unit (CPU) is a 16 bit processor for high-speed, real time applications, and for large multi-user, multi- task, time shared

Vice President Mike Pence Visits Kennedy Space Center

NASA Image and Video Library

2017-07-06

NASA Kennedy Space Center Director Robert Cabana addresses agency leaders, U.S. and Florida government officials, and employees inside the Vehicle Assembly Building during a visit by Vice President Mike Pence. Pence thanked employees for advancing American leadership in space. During his visit to Kennedy, the Vice President also toured several facilities highlighting the public-private partnerships, as both NASA and commercial companies prepare to launch American astronauts from the multi-user spaceport.

Vice President Mike Pence Visits Kennedy Space Center

NASA Image and Video Library

2017-07-06

Vice President Mike Pence speaks before an audience of NASA leaders, U.S. and Florida government officials, and employees inside the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida. Pence thanked employees for advancing American leadership in space. During his visit to Kennedy, the Vice President also toured several facilities highlighting the public-private partnerships, as both NASA and commercial companies prepare to launch American astronauts from the multi-user spaceport.

A computerized support system to cooperative training in emergency scenarios management and its application to an oil port domain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balducelli, C.; Bologna, S.; Di Costanzo, G.

1995-12-31

The paper describes part of the results achieved in the framework of the MUSTER project (Multi-Users System for Training and Evaluating Environmental Emergency Response). The aim of this project is to define the detailed specifications of a computer based system supporting collaborative training for emergency management. A system prototype has been implemented to support the refinement and improvement of the system specifications.

Up on The 606. Understanding the Use of a New Elevated Pedestrian and Bicycle Trail in Chicago, Illinois

Treesearch

Paul H. Gobster; Sonya Sachdeva; Greg Lindsey

2017-01-01

The 606 is the world's first multiuse elevated trail, extending for 2.7 mi (4.35 km) through diverse neighborhoods whose per capita of open space is one of the lowest in Chicago. The trail connects six ground-level parks and is managed for recreation, but it also serves as a cross-town transportation connector and was funded partially with transportation dollars....

Pad 39B Flame Trench Upgrades and modifications

NASA Image and Video Library

2016-03-03

Upgrades and modifications continue to the flame trench at Launch Pad 39B at NASA’s Kennedy Space Center in Florida. Pad B is being refurbished to support the launch of NASA’s Space Launch System rocket. The Ground Systems Development and Operations (GSDO) Program at Kennedy is helping transform the space center into a multi-user spaceport and prepare for Exploration Mission-1, deep-space missions, and the journey to Mars.

KSC-2014-3532

NASA Image and Video Library

2014-08-14

CAPE CANAVERAL, Fla. – The lightning suppression system on Launch Pad 39B soon may be put to the test by a thunderstorm moving through the launch complex at NASA’s Kennedy Space Center in Florida. Kennedy's Ground Support Development and Operations Program is hard at work transforming the center's facilities into a multi-user spaceport, when the weather permits. For more on Kennedy Space Center, visit http://www.nasa.gov/kennedy. Photo credit: NASA/Ben Smegelsky

An Automated Solution to the Multiuser Carved Data Ascription Problem

DTIC Science & Technology

2010-12-01

computer might have several authorized users. It is also common in many families, as well as in libraries, hospitals, and Internet cafes . Another way for...starting disk sector number were used in preference to features such as the Microsoft Office em- bedded “Creator” attribute. We believe that this is...with exemplars in a reference collection. 5) Validation Server: Although the technique presented in this paper is effective, it is time consuming to

On the Value of Second Life for Students' Engagement in Blended and Online Courses: A Comparative Study from the Higher Education in Greece

ERIC Educational Resources Information Center

Pellas, Nikolaos; Kazanidis, Ioannis

2015-01-01

Nowadays three-dimensional (3D) multi-user virtual worlds (VWs) are the most well-known candidate platforms in Higher education. Despite the growing number of notable studies that have presented VWs as valuable platforms for the e-Education, there is still a paucity of a comparative study in order to be determined the degree of the students'…

Multi-User Performance Issues in Wireless Impulse Radio Networks

DTIC Science & Technology

2004-01-01

Performance Issues in Wireless Impulse Radio Networks 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR( S ) 5d. PROJECT...NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME( S ) AND ADDRESS(ES) North Carolina State University,Department of...Electrical and Computer Engineering,Raleigh,NC,27695 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME( S ) AND ADDRESS(ES) 10

Control Channel Vulnerability Analysis of the Institute of Electrical and Electronics Engineers 802.16m-2011 and 802.16- 2009 Standards

DTIC Science & Technology

2012-09-01

scheduler to adapt its uplink and downlink assignments to channel conditions. Sleep mode is used by the MS to minimize power drain and radio...is addressed in one resource unit, while for multi-user (MU) schemes , multiple users can be scheduled in one resource unit. Open-loop techniques...17  7.  Mobility and Power Management ......................................... 18  8.  Scheduling Services

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 sources from which they chose to gather data. There are indications in my results that novel interventions like a Multi-user Virtual Environment might act as a catalyst for change in student learning. Further research using these techniques may enable a better understanding of the interaction between self-efficacy and scientific inquiry, and eventually science learning outcomes.

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-independent middleware that maintains the states, sessions, and interactions of individual users of the software applications, (4) an application programming interface to enable tight integration of applications and the middleware. The infrastructure is able to support any software applications running under the Windows or Unix platforms. The resulting technologies not only are applicable to NASA mission operations, but also useful in other situations such as design reviews, brainstorming sessions, and business meetings, as they can benefit from having the participants concurrently interact with the software applications (e.g., presentation applications and CAD design tools) to illustrate their ideas and provide inputs.

NRL’s Forward Technology Solar Cell Experiment Flies as Part of MISSE-5 Aboard Space Shuttle Discovery Mission

DTIC Science & Technology

2006-01-01

Satellite Service in cooperation with ARISS (Amateur Radio on the International Space Station) and provides a PSK-31 multiuser transponder, an FM voice...interference with existing ARISS missions. PCSat2 has quad redun- dant transmit inhibits for extravehicular activity safety issues, thus it is easy...to deactivate to avoid any issues with other UHF ARISS experiments that may be acti- vated in the future. Acknowledgments: The authors acknowledge

Copper-palladium core-shell as an anode in a multi-fuel membraneless nanofluidic fuel cell: toward a new era of small energy conversion devices.

PubMed

Maya-Cornejo, J; Ortiz-Ortega, E; Álvarez-Contreras, L; Arjona, N; Guerra-Balcázar, M; Ledesma-García, J; Arriaga, L G

2015-02-14

A membraneless nanofluidic fuel cell with flow-through electrodes that works with several fuels (individually or mixed): methanol, ethanol, glycerol and ethylene-glycol in alkaline media is presented. For this application, an efficient Cu@Pd electrocatalyst was synthesized and tested, resulting outstanding performance until now reported, opening the possibility of power nano-devices for multi-uses purposes, regardless of fuel re-charge employed.

KSC-2014-3527

NASA Image and Video Library

2014-08-14

CAPE CANAVERAL, Fla. – A storm is brewing over Launch Complex 39 at NASA’s Kennedy Space Center in Florida. At left are the news networks' facilities on the NASA Press Site. At right is the behemoth Vehicle Assembly Building. Kennedy's Ground Support Development and Operations Program is hard at work transforming the center's facilities into a multi-user spaceport, when the weather permits. For more on Kennedy Space Center, visit http://www.nasa.gov/kennedy. Photo credit: NASA/Ben Smegelsky

Compressive Channel Estimation and Tracking for Large Arrays in mm Wave Picocells

DTIC Science & Technology

2014-01-01

abling sophisticated adaptation, including frequency-selective spatiotemporal processing (e.g., per subcarrier beamforming in OFDM systems). This approach...subarrays are certainly required for more advanced functionalities such as multiuser MIMO [17], spatial multiplexing [18], [19], [20], [21], [22], and...case, a regu- larly spaced 2D array), an estimate of the N2t,1D × N2r,1D MIMO channel matrix H can be efficiently arrived at by estimating the spatial

Earth Systems Questions in Experimental Climate Change Science: Pressing Questions and Necessary Facilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Osmond, B.

2002-05-20

Sixty-four scientists from universities, national laboratories, and other research institutions worldwide met to evaluate the feasibility and potential of the Biosphere2 Laboratory (B2L) as an inclusive multi-user scientific facility (i.e., a facility open to researchers from all institutions, according to agreed principles of access) for earth system studies and engineering research, education, and training relevant to the mission of the United States Department of Energy (DOE).

CIR MDCA replacement

NASA Image and Video Library

2015-05-13

ISS043E190395 (05/13/2015) --- NASA astronaut Terry Virts prepares the Multi-user Droplet Combustion Apparatus from inside the Combustion Integrated Rack for upcoming runs of the FLame Extinguishment Experiment, or FLEX-2. The FLEX-2 experiment studies how quickly fuel burns, the conditions required for soot to form, and how mixtures of fuels evaporate before burning. Understanding these processes could lead to the production of a safer spacecraft as well as increased fuel efficiency for engines using liquid fuel on Earth.

Collaborative Systems and Multi-user Interfaces: Computer-based Tools for Cooperative Problem Solving

DTIC Science & Technology

1986-10-31

Reference Card Given to Participants) Cognoter Reference Select = LeftButton Menu = MiddleButton TitleBar menu for tool operations Item menu for item...collaborative tools and their uses, the Colab system and the Cognoter presentation tool were implemented and used for both real and posed idea organization...tasks. To test the system design and its effect on structured problem-solving, many early Colab/ Cognoter meetings were monitored and a series of

The Impact of Student Self-efficacy on Scientific Inquiry Skills: An Exploratory Investigation in River City, a Multi-user Virtual Environment

NASA Astrophysics Data System (ADS)

Ketelhut, Diane Jass

2007-02-01

This exploratory study investigated data-gathering behaviors exhibited by 100 seventh-grade students as they participated in a scientific inquiry-based curriculum project delivered by a multi-user virtual environment (MUVE). This research examined the relationship between students' self-efficacy on entry into the authentic scientific activity and the longitudinal data-gathering behaviors they employed while engaged in that process. Three waves of student behavior data were gathered from a server-side database that recorded all student activity in the MUVE; these data were analyzed using individual growth modeling. The study found that self-efficacy correlated with the number of data-gathering behaviors in which students initially engaged, with high self-efficacy students engaging in more data gathering than students with low self-efficacy. Also, the impact of student self-efficacy on rate of change in data gathering behavior differed by gender. However, by the end of their time in the MUVE, initial student self-efficacy no longer correlated with data gathering behaviors. In addition, students' level of self-efficacy did not affect how many different sources from which they chose to gather data. These results suggest that embedding science inquiry curricula in novel platforms like a MUVE might act as a catalyst for change in students' self-efficacy and learning processes.

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. Copyright © 2014 Elsevier Ltd. All rights reserved.

Multi-User Spaceport Update News Conference

NASA Image and Video Library

2014-01-23

CAPE CANAVERAL, Fla. – Sierra Nevada Corporation, or SNC, Space Systems, announces the steps the company will take to prepare for a November 2016 orbital flight of its Dream Chaser spacecraft from Florida’s Space Coast during a news conference at NASA’s Kennedy Space Center in Florida. Participants are, from left, Michael Curie, NASA spokesman, Bob Cabana, director of Kennedy, Michael Gass, president and CEO of United Launch Alliance, or ULA, Frank DiBello, president and CEO of Space Florida, Mark Sirangelo, corporate vice president and head of SNC Space Systems, Larry Price, Lockheed Martin Space Systems deputy program manager for NASA's Orion spacecraft, and Steve Lindsey, Dream Chaser program manager for SNC Space Systems. The steps are considered substantial for SNC and important to plans by NASA and Space Florida for Kennedy’s transformation into a multi-user spaceport for both commercial and government customers. SNC said it plans to work with ULA to launch the Dream Chaser spacecraft into orbit atop an Atlas V rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station intends to land the winged spacecraft at Kennedy’s 3.5-mile long runway at the Shuttle Landing Facility lease office space at Exploration Park, right outside Kennedy’s gates and process the spacecraft in the high bay of the Operations and Checkout Building at Kennedy, with Lockheed Martin performing the work. Photo credit: NASA/Kim Shiflett

[Frequency of healthy eating habits measured by the 10 Steps to Healthy Eating score proposed by the Ministry of Health: Pelotas, Rio Grande do Sul State, Brazil].

PubMed

Vinholes, Daniele Botelho; Assunção, Maria Cecília Formoso; Neutzling, Marilda Borges

2009-04-01

This study aimed to measure frequency of healthy eating habits and associated factors using the 10 Steps to Healthy Eating score proposed by the Ministry of Health in the adult population in Pelotas, Rio Grande do Sul State, Brazil. A cross-sectional population-based survey was conducted on a cluster sample of 3,136 adult residents in Pelotas. The frequency of each step to healthy eating was collected with a pre-coded questionnaire. Data analysis consisted of descriptive analysis, followed by bivariate analysis using the chi-square test. Only 1.1% of the population followed all the recommended steps. The average number of steps was six. Step four, salt intake, showed the highest frequency, while step nine, physical activity, showed the lowest. Knowledge of the population's eating habits and their distribution according to demographic and socioeconomic variables is important to guide local and national strategies to promote healthy eating habits and thus improve quality of life.

The NATA code; theory and analysis. Volume 2: User's manual

NASA Technical Reports Server (NTRS)

Bade, W. L.; Yos, J. M.

1975-01-01

The NATA code is a computer program for calculating quasi-one-dimensional gas flow in axisymmetric nozzles and rectangular channels, primarily to describe conditions in electric archeated wind tunnels. The program provides solutions based on frozen chemistry, chemical equilibrium, and nonequilibrium flow with finite reaction rates. The shear and heat flux on the nozzle wall are calculated and boundary layer displacement effects on the inviscid flow are taken into account. The program contains compiled-in thermochemical, chemical kinetic and transport cross section data for high-temperature air, CO2-N2-Ar mixtures, helium, and argon. It calculates stagnation conditions on axisymmetric or two-dimensional models and conditions on the flat surface of a blunt wedge. Included in the report are: definitions of the inputs and outputs; precoded data on gas models, reactions, thermodynamic and transport properties of species, and nozzle geometries; explanations of diagnostic outputs and code abort conditions; test problems; and a user's manual for an auxiliary program (NOZFIT) used to set up analytical curvefits to nozzle profiles.

Subtyping depression by clinical features: the Australasian database.

PubMed

Parker, G; Roy, K; Hadzi-Pavlovic, D; Mitchell, P; Wilhelm, K; Menkes, D B; Snowdon, J; Loo, C; Schweitzer, I

2000-01-01

To distinguish psychotic, melancholic and a residual non-melancholic class on the basis of clinical features alone. Previous studies at our Mood Disorders Unit (MDU) favour a hierarchical model, with the classes able to be distinguished by two specific clinical features, but any such intramural study risks rater bias and requires external replication. This replication study involved 27 Australasian psychiatrist raters, thus extending the sample and raters beyond the MDU facility. They collected clinical feature data using a standardized assessment with precoded rating options. A psychotic depression (PD) class was derived by respecting DSM-IV decision rules while a cluster analysis distinguished melancholic (MEL) and non-melancholic classes. The MELs were distinguished virtually entirely by the presence of significant psychomotor disturbance (PMD), as rated by the observationally based CORE measure, with over-representation on only three of an extensive set of 'endogeneity symptoms'. In comparison to PMD, endogeneity symptoms appear to be poor indicators of 'melancholic' type, confounding typology with severity. Results again support the hierarchical model.

Pediatric ocular trauma score as a prognostic tool in the management of pediatric traumatic cataracts.

PubMed

Shah, Mehul A; Agrawal, Rupesh; Teoh, Ryan; Shah, Shreya M; Patel, Kashyap; Gupta, Satyam; Gosai, Siddharth

2017-05-01

To introduce and validate the pediatric ocular trauma score (POTS) - a mathematical model to predict visual outcome trauma in children with traumatic cataract METHODS: In this retrospective cohort study, medical records of consecutive children with traumatic cataracts aged 18 and below were retrieved and analysed. Data collected included age, gender, visual acuity, anterior segment and posterior segment findings, nature of surgery, treatment for amblyopia, follow-up, and final outcome was recorded on a precoded data information sheet. POTS was derived based on the ocular trauma score (OTS), adjusting for age of patient and location of the injury. Visual outcome was predicted using the OTS and the POTS and using receiver operating characteristic (ROC) curves. POTS predicted outcomes were more accurate compared to that of OTS (p = 0.014). POTS is a more sensitive and specific score with more accurate predicted outcomes compared to OTS, and is a viable tool to predict visual outcomes of pediatric ocular trauma with traumatic cataract.

Path-Following Solutions Of Nonlinear Equations

NASA Technical Reports Server (NTRS)

Barger, Raymond L.; Walters, Robert W.

1989-01-01

Report describes some path-following techniques for solution of nonlinear equations and compares with other methods. Use of multipurpose techniques applicable at more than one stage of path-following computation results in system relatively simple to understand, program, and use. Comparison of techniques with method of parametric differentiation (MPD) reveals definite advantages for path-following methods. Emphasis in investigation on multiuse techniques being applied at more than one stage of path-following computation. Incorporation of multipurpose techniques results in concise computer code relatively simple to use.

KSC-2009-2521

NASA Image and Video Library

2009-04-02

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, technicians help with the installation of the Science Instrument Command and Data Handling Unit, or SIC&DH, on the Multi-Use Lightweight Equipment Carrier. The SIC&DH will be installed on the Hubble Space Telescope during space shuttle Atlantis' STS-125 mission. This unit will replace the one that suffered a failure aboard the orbiting telescope on Sept. 27, 2008. Atlantis is targeted for launch on May 12. Photo credit: NASA/Dimitri Gerondidakis

KSC-08pd2637

NASA Image and Video Library

2008-09-17

CAPE CANAVERAL, Fla. - In the Payload Hazardous Servicing Facility at NASA’s Kennedy Space Center, the Multi-Use Logistic Equipment, or MULE, carrier is moved toward the payload canister. The carrier is one of four associated with the STS-125 mission to service the Hubble Space Telescope. It will be installed in the payload canister for transfer to Launch Pad 39A. At the pad, all the carriers will be loaded into space shuttle Atlantis’ payload bay. Launch of Atlantis is targeted for Oct. 10. Photo credit: NASA/Jack Pfaller

KSC-08pd2636

NASA Image and Video Library

2008-09-17

CAPE CANAVERAL, Fla. - In the Payload Hazardous Servicing Facility at NASA’s Kennedy Space Center, an overhead crane lifts the Multi-Use Logistic Equipment, or MULE, carrier. The carrier is one of four associated with the STS-125 mission to service the Hubble Space Telescope. It will be installed in the payload canister for transfer to Launch Pad 39A. At the pad, all the carriers will be loaded into space shuttle Atlantis’ payload bay. Launch of Atlantis is targeted for Oct. 10. Photo credit: NASA/Jack Pfaller

KSC-08pd2638

NASA Image and Video Library

2008-09-17

CAPE CANAVERAL, Fla. - In the Payload Hazardous Servicing Facility at NASA’s Kennedy Space Center, the Multi-Use Logistic Equipment, or MULE, carrier is moved toward the payload canister. The carrier is one of four associated with the STS-125 mission to service the Hubble Space Telescope. It will be installed in the payload canister for transfer to Launch Pad 39A. At the pad, all the carriers will be loaded into space shuttle Atlantis’ payload bay. Launch of Atlantis is targeted for Oct. 10. Photo credit: NASA/Jack Pfaller

KSC-2009-2520

NASA Image and Video Library

2009-04-02

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, technicians help with the installation of the Science Instrument Command and Data Handling Unit, or SIC&DH, on the Multi-Use Lightweight Equipment Carrier. The SIC&DH will be installed on the Hubble Space Telescope during space shuttle Atlantis' STS-125 mission. This unit will replace the one that suffered a failure aboard the orbiting telescope on Sept. 27, 2008. Atlantis is targeted for launch on May 12. Photo credit: NASA/Dimitri Gerondidakis

KSC-2009-2522

NASA Image and Video Library

2009-04-02

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, technicians look over the Science Instrument Command and Data Handling Unit, or SIC&DH, installed on the Multi-Use Lightweight Equipment Carrier. The SIC&DH will be installed on the Hubble Space Telescope during space shuttle Atlantis' STS-125 mission. This unit will replace the one that suffered a failure aboard the orbiting telescope on Sept. 27, 2008. Atlantis is targeted for launch on May 12. Photo credit: NASA/Dimitri Gerondidakis

KSC-2009-2523

NASA Image and Video Library

2009-04-02

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, technicians check the Multi-Use Lightweight Equipment Carrier where the Science Instrument Command and Data Handling Unit, or SIC&DH, is being installed. The SIC&DH will be installed on the Hubble Space Telescope during space shuttle Atlantis' STS-125 mission. This unit will replace the one that suffered a failure aboard the orbiting telescope on Sept. 27, 2008. Atlantis is targeted for launch on May 12. Photo credit: NASA/Dimitri Gerondidakis

KSC-08pd2635

NASA Image and Video Library

2008-09-17

CAPE CANAVERAL, Fla. - In the Payload Hazardous Servicing Facility at NASA’s Kennedy Space Center, an overhead crane lifts the Multi-Use Logistic Equipment, or MULE, carrier. The carrier is one of four associated with the STS-125 mission to service the Hubble Space Telescope. It will be installed in the payload canister for transfer to Launch Pad 39A. At the pad, all the carriers will be loaded into space shuttle Atlantis’ payload bay. Launch of Atlantis is targeted for Oct. 10. Photo credit: NASA/Jack Pfaller

Satellite-aided coastal zone monitoring and vessel traffic system

NASA Technical Reports Server (NTRS)

Baker, J. L.

1981-01-01

The development and demonstration of a coastal zone monitoring and vessel traffic system is described. This technique uses a LORAN-C navigational system and relays signals via the ATS-3 satellite to a computer driven color video display for real time control. Multi-use applications of the system to search and rescue operations, coastal zone management and marine safety are described. It is emphasized that among the advantages of the system are: its unlimited range; compatibility with existing navigation systems; and relatively inexpensive cost.

Micromachined modulator arrays for use in free-space optical communication systems

NASA Astrophysics Data System (ADS)

Lewis, Keith L.; Ridley, Kevin D.; McNie, Mark E.; Smith, Gilbert W.; Scott, Andrew M.

2004-12-01

A summary is presented of some of the design criteria relevant to the realisation of silicon micromachined modulator arrays for use in free-space optical communication systems. Theoretical performance levels achievable are compared with values measured on experimental devices produced using a modified Multi-User MEMS Process (MUMPS). Devices capable of realising modulation rates in excess of 300 kHz are described and their optical characteristics compared with published data on devices based on multiple quantum well technology.

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.

Cushion system for multi-use child safety seat

NASA Technical Reports Server (NTRS)

Elrod, Susan V. (Inventor); Dabney, Richard W. (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.

Power Systems for Human Exploration Missions

NASA Technical Reports Server (NTRS)

Cataldo, Robert L.

1998-01-01

Power system options were reviewed for their appropriateness to meet mission requirements and guidelines. Contending system technologies include: solar, nuclear, isotopic, electro-chemical and chemical. Mission elements can basically be placed into two categories; in-space transportation systems, both cargo and piloted; and surface systems, both stationary and mobile. All transportation and surface element power system requirements were assessed for application synergies that would suggest common hardware (duplicates of the same or similar design) or multi-use (reuse system in a different application/location), wherever prudent.

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.

The ACE multi-user web-based Robotic Observatory Control System

NASA Astrophysics Data System (ADS)

Mack, P.

2003-05-01

We have developed an observatory control system that can be operated in interactive, remote or robotic modes. In interactive and remote mode the observer typically acquires the first object then creates a script through a window interface to complete observations for the rest of the night. The system closes early in the event of bad weather. In robotic mode observations are submitted ahead of time through a web-based interface. We present observations made with a 1.0-m telescope using these methods.