System performances of optical space code-division multiple-access-based fiber-optic two-dimensional parallel data link.

Science.gov (United States)

Nakamura, M; Kitayama, K

1998-05-10

Optical space code-division multiple access is a scheme to multiplex and link data between two-dimensional processors such as smart pixels and spatial light modulators or arrays of optical sources like vertical-cavity surface-emitting lasers. We examine the multiplexing characteristics of optical space code-division multiple access by using optical orthogonal signature patterns. The probability density function of interference noise in interfering optical orthogonal signature patterns is calculated. The bit-error rate is derived from the result and plotted as a function of receiver threshold, code length, code weight, and number of users. Furthermore, we propose a prethresholding method to suppress the interference noise, and we experimentally verify that the method works effectively in improving system performance.

Gigabit Ethernet signal transmission using asynchronous optical code division multiple access.

Science.gov (United States)

Ma, Philip Y; Fok, Mable P; Shastri, Bhavin J; Wu, Ben; Prucnal, Paul R

2015-12-15

We propose and experimentally demonstrate a novel architecture for interfacing and transmitting a Gigabit Ethernet (GbE) signal using asynchronous incoherent optical code division multiple access (OCDMA). This is the first such asynchronous incoherent OCDMA system carrying GbE data being demonstrated to be working among multi-users where each user is operating with an independent clock/data rate and is granted random access to the network. Three major components, the GbE interface, the OCDMA transmitter, and the OCDMA receiver are discussed in detail. The performance of the system is studied and characterized through measuring eye diagrams, bit-error rate and packet loss rate in real-time file transfer. Our Letter also addresses the near-far problem and realizes asynchronous transmission and detection of signal.

Code division multiple-access techniques in optical fiber networks. II - Systems performance analysis

Science.gov (United States)

Salehi, Jawad A.; Brackett, Charles A.

1989-08-01

A technique based on optical orthogonal codes was presented by Salehi (1989) to establish a fiber-optic code-division multiple-access (FO-CDMA) communications system. The results are used to derive the bit error rate of the proposed FO-CDMA system as a function of data rate, code length, code weight, number of users, and receiver threshold. The performance characteristics for a variety of system parameters are discussed. A means of reducing the effective multiple-access interference signal by placing an optical hard-limiter at the front end of the desired optical correlator is presented. Performance calculations are shown for the FO-CDMA with an ideal optical hard-limiter, and it is shown that using a optical hard-limiter would, in general, improve system performance.

A satellite mobile communication system based on Band-Limited Quasi-Synchronous Code Division Multiple Access (BLQS-CDMA)

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Degaudenzi, R.; Elia, C.; Viola, R.

1990-01-01

Discussed here is a new approach to code division multiple access applied to a mobile system for voice (and data) services based on Band Limited Quasi Synchronous Code Division Multiple Access (BLQS-CDMA). The system requires users to be chip synchronized to reduce the contribution of self-interference and to make use of voice activation in order to increase the satellite power efficiency. In order to achieve spectral efficiency, Nyquist chip pulse shaping is used with no detection performance impairment. The synchronization problems are solved in the forward link by distributing a master code, whereas carrier forced activation and closed loop control techniques have been adopted in the return link. System performance sensitivity to nonlinear amplification and timing/frequency synchronization errors are analyzed.

Average Likelihood Methods of Classification of Code Division Multiple Access (CDMA)

Science.gov (United States)

2016-05-01

subject to code matrices that follows the structure given by (113). [⃗ yR y⃗I ] = √ Es 2L [ GR1 −GI1 GI2 GR2 ] [ QR −QI QI QR ] [⃗ bR b⃗I ] + [⃗ nR n⃗I... QR ] [⃗ b+ b⃗− ] + [⃗ n+ n⃗− ] (115) The average likelihood for type 4 CDMA (116) is a special case of type 1 CDMA with twice the code length and...AVERAGE LIKELIHOOD METHODS OF CLASSIFICATION OF CODE DIVISION MULTIPLE ACCESS (CDMA) MAY 2016 FINAL TECHNICAL REPORT APPROVED FOR PUBLIC RELEASE

Polarization diversity scheme on spectral polarization coding optical code-division multiple-access network

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Yen, Chih-Ta; Huang, Jen-Fa; Chang, Yao-Tang; Chen, Bo-Hau

2010-12-01

We present an experiment demonstrating the spectral-polarization coding optical code-division multiple-access system introduced with a nonideal state of polarization (SOP) matching conditions. In the proposed system, the encoding and double balanced-detection processes are implemented using a polarization-diversity scheme. Because of the quasiorthogonality of Hadamard codes combining with array waveguide grating routers and a polarization beam splitter, the proposed codec pair can encode-decode multiple code words of Hadamard code while retaining the ability for multiple-access interference cancellation. The experimental results demonstrate that when the system is maintained with an orthogonal SOP for each user, an effective reduction in the phase-induced intensity noise is obtained. The analytical SNR values are found to overstate the experimental results by around 2 dB when the received effective power is large. This is mainly limited by insertion losses of components and a nonflattened optical light source. Furthermore, the matching conditions can be improved by decreasing nonideal influences.

Cascaded holographic polymer reflection grating filters for optical-code-division multiple-access applications.

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Kostuk, Raymond K; Maeda, Wendi; Chen, Chia-Hung; Djordjevic, Ivan; Vasic, Bane

2005-12-10

We evaluate the use of edge-illuminated holographic Bragg filters formed in phenanthrenequinone-doped poly(methyl methacrylate) for optical-code-division multiple-access (OCDMA) coding and decoding applications. Experimental cascaded Bragg filters are formed to select two different wavelengths with a fixed distance between the gratings and are directly coupled to a fiber-measurement system. The configuration and tolerances of the cascaded gratings are shown to be practical for time-wavelength OCDMA applications.

Hermitian symmetry free optical-single-carrier frequency division multiple access for visible light communication

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Azim, Ali W.; Le Guennec, Yannis; Maury, Ghislaine

2018-05-01

Optical-orthogonal frequency division multiplexing (O-OFDM) is an effective scheme for visible light communications (VLC), offering a candid extension to multiple access (MA) scenarios, i.e., O-OFDMA. However, O-OFDMA exhibits high peak-to-average power ratio (PAPR), which exacerbates the non-linear distortions from the light emitting diode (LED). To overcome high PAPR while sustaining MA, optical-single-carrier frequency-division multiple access (O-SCFDMA) is used. For both O-OFDMA and O-SCFDMA, Hermitian symmetry (HS) constraint is imposed in frequency-domain (FD) to obtain a real-valued time-domain (TD) signal for intensity modulation-direct detection (IM-DD) implementation of VLC. Howbeit, HS results in an increase of PAPR for O-SCFDMA. In this regard, we propose HS free (HSF) O-SCFDMA (HSFO-SCFDMA). We compare HSFO-SCFDMA with several approaches in key parameters, such as, bit error rate (BER), optical power penalty, PAPR, quantization, electrical power efficiency and system complexity. BER performance and optical power penalty is evaluated considering multipath VLC channel and taking into account the bandwidth limitation of LED in combination with its optimized driver. It is illustrated that HSFO-SCFDMA outperforms other alternatives.

Performance enhancement of optical code-division multiple-access systems using transposed modified Walsh code

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Sikder, Somali; Ghosh, Shila

2018-02-01

This paper presents the construction of unipolar transposed modified Walsh code (TMWC) and analysis of its performance in optical code-division multiple-access (OCDMA) systems. Specifically, the signal-to-noise ratio, bit error rate (BER), cardinality, and spectral efficiency were investigated. The theoretical analysis demonstrated that the wavelength-hopping time-spreading system using TMWC was robust against multiple-access interference and more spectrally efficient than systems using other existing OCDMA codes. In particular, the spectral efficiency was calculated to be 1.0370 when TMWC of weight 3 was employed. The BER and eye pattern for the designed TMWC were also successfully obtained using OptiSystem simulation software. The results indicate that the proposed code design is promising for enhancing network capacity.

Pulse patterning effect in optical pulse division multiplexing for flexible single wavelength multiple access optical network

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Jung, Sun-Young; Kim, Chang-Hun; Han, Sang-Kook

2018-05-01

A demand for high spectral efficiency requires multiple access within a single wavelength, but the uplink signals are significantly degraded because of optical beat interference (OBI) in intensity modulation/direct detection system. An optical pulse division multiplexing (OPDM) technique was proposed that could effectively reduce the OBI via a simple method as long as near-orthogonality is satisfied, but the condition was strict, and thus, the number of multiplexing units was very limited. We propose pulse pattern enhanced OPDM (e-OPDM) to reduce the OBI and improve the flexibility in multiple access within a single wavelength. The performance of the e-OPDM and patterning effect are experimentally verified after 23-km single mode fiber transmission. By employing pulse patterning in OPDM, the tight requirement was relaxed by extending the optical delay dynamic range. This could support more number of access with reduced OBI, which could eventually enhance a multiple access function.

Iterative Pilot-Layer Aided Channel Estimation with Emphasis on Interleave-Division Multiple Access Systems

OpenAIRE

Schoeneich Hendrik; Hoeher Peter Adam

2006-01-01

Channel estimation schemes suitable for interleave-division multiple access (IDMA) systems are presented. Training and data are superimposed. Training-based and semiblind linear channel estimators are derived and their performance is discussed and compared. Monte Carlo simulation results are presented showing that the derived channel estimators in conjunction with a superimposed pilot sequence and chip-by-chip processing are able to track fast-fading frequency-selective channels. As opposed ...

Beat Noise Cancellation in 2-D Optical Code-Division Multiple-Access Systems Using Optical Hard-Limiter Array

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Dang, Ngoc T.; Pham, Anh T.; Cheng, Zixue

We analyze the beat noise cancellation in two-dimensional optical code-division multiple-access (2-D OCDMA) systems using an optical hard-limiter (OHL) array. The Gaussian shape of optical pulse is assumed and the impact of pulse propagation is considered. We also take into account the receiver noise and multiple access interference (MAI) in the analysis. The numerical results show that, when OHL array is employed, the system performance is greatly improved compared with the cases without OHL array. Also, parameters needed for practical system design are comprehensively analyzed.

Implementation of Multiple Access Techniques Applicable for Maritime Satellite Communications

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Stojce Dimov Ilcev

2013-12-01

Full Text Available In this paper are introduced fundamentals, characteristics, advantages and disadvantages of Multiple Access (MA employed as transmission techniques in the Maritime Mobile Satellite Communications (MMSC between ships and Coast Earth Station (CES via Geostationary Earth Orbit (GEO or Not-GEO satellite constellations. In fixed satellite communication, as a rule, especially in MMSC many users are active at the same time. The problem of simultaneous communications between many single or multipoint mobile satellite users can be solved by using MA technique, such as Frequency Division Multiple Access (FDMA, Time Division Multiple Access (TDMA, Code Division Multiple Access (CDMA, Space Division Multiple Access (SDMA and Random (Packet Division Multiple Access (RDMA. Since the resources of the systems such as the transmitting power and the bandwidth are limited, it is advisable to use the channels with complete charge and to create a different MA to the channel. This generates a problem of summation and separation of signals in the transmission and reception parts, respectively. Deciding this problem consists in the development of orthogonal channels of transmission in order to divide signals from various users unambiguously on the reception part.

Electro-optical time gating based on Mach-Zehnder modulator for multiple access interference elimination in optical code-division multiple access networks

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Chen, Yinfang; Wang, Rong; Fang, Tao; Pu, Tao; Xiang, Peng; Zheng, Jilin; Zhu, Huatao

2014-05-01

An electro-optical time gating technique, which is based on an electrical return-to-zero (RZ) pulse driven Mach-Zehnder modulator (MZM) for eliminating multiple access interference (MAI) in optical code-division multiple access (OCDMA) networks is proposed. This technique is successfully simulated in an eight-user two-dimensional wavelength-hopping time-spreading system, as well as in a three-user temporal phase encoding system. Results show that in both systems the MAI noise is efficiently removed and the average received power penalty improved. Both achieve error-free transmissions at a bit rate of 2.5 Gb/s. In addition, we also individually discuss effects of parameters in two systems, such as the extinction ratio of the MZM, the duty cycle of the driven RZ pulse, and the time misalignment between the driven pulse and the decoded autocorrelation peak, on the output bit error rate performance. Our work shows that employing a common MZM as a thresholder provides another probability and an interesting cost-effective choice for a smart size, low energy, and less complex thresholding technique for integrated detection in OCDMA networks.

Filter multiplexing by use of spatial Code Division Multiple Access approach.

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Solomon, Jonathan; Zalevsky, Zeev; Mendlovic, David; Monreal, Javier Garcia

2003-02-10

The increasing popularity of optical communication has also brought a demand for a broader bandwidth. The trend, naturally, was to implement methods from traditional electronic communication. One of the most effective traditional methods is Code Division Multiple Access. In this research, we suggest the use of this approach for spatial coding applied to images. The approach is to multiplex several filters into one plane while keeping their mutual orthogonality. It is shown that if the filters are limited by their bandwidth, the output of all the filters can be sampled in the original image resolution and fully recovered through an all-optical setup. The theoretical analysis of such a setup is verified in an experimental demonstration.

Reduction of the near-far effect in mobile communication systems with Code-Division Multiple-Access

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Purchla, Magdalena

2006-02-01

In this paper the basic methods for reducing Multiple Access Interference (MAI) and combating the near-far effect in Direct-Sequence Code-Division Multiple-Access (DS-CDMA) mobile communication systems are presented. MAI and the near-far effect are inevitable in DS-CDMA systems with quasi-orthogonal spreading sequences. An effective method of reducing MAI can increase the capacity of the system that is why so many researchers are working in this field. In this article three most important techniques of decreasing MAI are presented: power control, multiuser detection and space-time processing. There is a short introduction to each topic and one or more examples found in literature of algorithms suitable for practical applications (although not all algorithms are yet used in existing systems).

Performance analysis of multiple interference suppression over asynchronous/synchronous optical code-division multiple-access system based on complementary/prime/shifted coding scheme

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Nieh, Ta-Chun; Yang, Chao-Chin; Huang, Jen-Fa

2011-08-01

A complete complementary/prime/shifted prime (CPS) code family for the optical code-division multiple-access (OCDMA) system is proposed. Based on the ability of complete complementary (CC) code, the multiple-access interference (MAI) can be suppressed and eliminated via spectral amplitude coding (SAC) OCDMA system under asynchronous/synchronous transmission. By utilizing the shifted prime (SP) code in the SAC scheme, the hardware implementation of encoder/decoder can be simplified with a reduced number of optical components, such as arrayed waveguide grating (AWG) and fiber Bragg grating (FBG). This system has a superior performance as compared to previous bipolar-bipolar coding OCDMA systems.

Performance Analysis of Direct-Sequence Code-Division Multiple-Access Communications with Asymmetric Quadrature Phase-Shift-Keying Modulation

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Wang, C.-W.; Stark, W.

2005-01-01

This article considers a quaternary direct-sequence code-division multiple-access (DS-CDMA) communication system with asymmetric quadrature phase-shift-keying (AQPSK) modulation for unequal error protection (UEP) capability. Both time synchronous and asynchronous cases are investigated. An expression for the probability distribution of the multiple-access interference is derived. The exact bit-error performance and the approximate performance using a Gaussian approximation and random signature sequences are evaluated by extending the techniques used for uniform quadrature phase-shift-keying (QPSK) and binary phase-shift-keying (BPSK) DS-CDMA systems. Finally, a general system model with unequal user power and the near-far problem is considered and analyzed. The results show that, for a system with UEP capability, the less protected data bits are more sensitive to the near-far effect that occurs in a multiple-access environment than are the more protected bits.

Mitigation of Beat Noise in Time Wavelength Optical Code-Division Multiple-Access Systems

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Bazan, Taher M.; Harle, David; Andonovic, Ivan

2006-11-01

This paper presents an analysis of two methods for enhancing the performance of two-dimensional time wavelength Optical code-division multiple-access systems by mitigating the effects of beat noise. The first methodology makes use of an optical hard limiter (OHL) in the receiver prior to the optical correlator; a general formula for the error probability as a function of crosstalk level for systems adopting OHLs is given, and the implications of the OHL's nonideal transfer characteristics are then examined. The second approach adopts pulse position modulation, and system performance is estimated and compared to that associated with on off keying.

Reducing BER of spectral-amplitude coding optical code-division multiple-access systems by single photodiode detection technique

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Al-Khafaji, H. M. R.; Aljunid, S. A.; Amphawan, A.; Fadhil, H. A.; Safar, A. M.

2013-03-01

In this paper, we present a single photodiode detection (SPD) technique for spectral-amplitude coding optical code-division multiple-access (SAC-OCDMA) systems. The proposed technique eliminates both phase-induced intensity noise (PIIN) and multiple-access interference (MAI) in the optical domain. Analytical results show that for 35 simultaneous users transmitting at data rate of 622 Mbps, the bit-error rate (BER) = 1.4x10^-28 for SPD technique is much better compared to 9.3x10^-6 and 9.6x10^-3 for the modified-AND as well as the AND detection techniques, respectively. Moreover, we verified the improved performance afforded by the proposed technique using data transmission simulations.

Measurements of stimulated-Raman-scattering-induced tilt in spectral-amplitude-coding optical code-division multiple-access systems

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Al-Qazwini, Zaineb A. T.; Abdullah, Mohamad K.; Mokhtar, Makhfudzah B.

2009-01-01

We measure the stimulated Raman scattering (SRS)-induced tilt in spectral-amplitude-coding optical code-division multiple-access (SAC-OCDMA) systems as a function of system main parameters (transmission distance, power per chip, and number of users) via computer simulations. The results show that SRS-induced tilt significantly increases as transmission distance, power per chip, or number of users grows.

Above the nominal limit performance evaluation of multiwavelength optical code-division multiple-access systems

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Inaty, Elie; Raad, Robert; Fortier, Paul; Shalaby, Hossam M. H.

2009-03-01

We provide an analysis for the performance of a multiwavelength optical code-division multiple-access (MW-OCDMA) network when the system is working above the nominal transmission rate limit imposed by passive encoding-decoding operation. We address the problem of overlapping in such a system and how it can directly affect the bit error rate (BER). A unified mathematical framework is presented under the assumption of one-coincidence sequences with nonrepeating wavelengths. A closed form expression of the multiple access interference limited BER is provided as a function of different system parameters. Results show that the performance of the MW-OCDMA system can be critically affected when working above the nominal limit, an event that can happen when the network operates at a high transmission rate. In addition, the impact of the derived error probability on the performance of two newly proposed medium access control (MAC) protocols, the S-ALOHA and the R3T, is also investigated. It is shown that for low transmission rates, the S-ALOHA is better than the R3T, while the R3T is better at very high transmission rates. In general, it is postulated that the R3T protocol suffers a higher delay mainly because of the presence of additional modes.

Multiple-Access Quantum-Classical Networks

Science.gov (United States)

Razavi, Mohsen

2011-10-01

A multi-user network that supports both classical and quantum communication is proposed. By relying on optical code-division multiple access techniques, this system offers simultaneous key exchange between multiple pairs of network users. A lower bound on the secure key generation rate will be derived for decoy-state quantum key distribution protocols.

Wavelength-encoding/temporal-spreading optical code division multiple-access system with in-fiber chirped moiré gratings.

Science.gov (United States)

Chen, L R; Smith, P W; de Sterke, C M

1999-07-20

We propose an optical code division multiple-access (OCDMA) system that uses in-fiber chirped moiré gratings (CMG's) for encoding and decoding of broadband pulses. In reflection the wavelength-selective and dispersive nature of CMG's can be used to implement wavelength-encoding/temporal-spreading OCDMA. We give examples of codes designed around the constraints imposed by the encoding devices and present numerical simulations that demonstrate the proposed concept.

Heterodyne detection using spectral line pairing for spectral phase encoding optical code division multiple access and dynamic dispersion compensation.

Science.gov (United States)

Yang, Yi; Foster, Mark; Khurgin, Jacob B; Cooper, A Brinton

2012-07-30

A novel coherent optical code-division multiple access (OCDMA) scheme is proposed that uses spectral line pairing to generate signals suitable for heterodyne decoding. Both signal and local reference are transmitted via a single optical fiber and a simple balanced receiver performs sourceless heterodyne detection, canceling speckle noise and multiple-access interference (MAI). To validate the idea, a 16 user fully loaded phase encoded system is simulated. Effects of fiber dispersion on system performance are studied as well. Both second and third order dispersion management is achieved by using a spectral phase encoder to adjust phase shifts of spectral components at the optical network unit (ONU).

Chip-interleaved optical code division multiple access relying on a photon-counting iterative successive interference canceller for free-space optical channels.

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Zhou, Xiaolin; Zheng, Xiaowei; Zhang, Rong; Hanzo, Lajos

2013-07-01

In this paper, we design a novel Poisson photon-counting based iterative successive interference cancellation (SIC) scheme for transmission over free-space optical (FSO) channels in the presence of both multiple access interference (MAI) as well as Gamma-Gamma atmospheric turbulence fading, shot-noise and background light. Our simulation results demonstrate that the proposed scheme exhibits a strong MAI suppression capability. Importantly, an order of magnitude of BER improvements may be achieved compared to the conventional chip-level optical code-division multiple-access (OCDMA) photon-counting detector.

Ultrafast all-optical code-division multiple-access networks

Science.gov (United States)

Kwong, Wing C.; Prucnal, Paul R.; Liu, Yanming

1992-12-01

In optical code-division multiple access (CDMA), the architecture of optical encoders/decoders is another important factor that needs to be considered, besides the correlation properties of those already extensively studied optical codes. The architecture of optical encoders/decoders affects, for example, the amount of power loss and length of optical delays that are associated with code sequence generation and correlation, which, in turn, affect the power budget, size, and cost of an optical CDMA system. Various CDMA coding architectures are studied in the paper. In contrast to the encoders/decoders used in prime networks (i.e., prime encodes/decoders), which generate, select, and correlate code sequences by a parallel combination of fiber-optic delay-lines, and in 2n networks (i.e., 2n encoders/decoders), which generate and correlate code sequences by a serial combination of 2 X 2 passive couplers and fiber delays with sequence selection performed in a parallel fashion, the modified 2n encoders/decoders generate, select, and correlate code sequences by a serial combination of directional couplers and delays. The power and delay- length requirements of the modified 2n encoders/decoders are compared to that of the prime and 2n encoders/decoders. A 100 Mbit/s optical CDMA experiment in free space demonstrating the feasibility of the all-serial coding architecture using a serial combination of 50/50 beam splitters and retroreflectors at 10 Tchip/s (i.e., 100,000 chip/bit) with 100 fs laser pulses is reported.

Optical code division multiple access secure communications systems with rapid reconfigurable polarization shift key user code

Science.gov (United States)

Gao, Kaiqiang; Wu, Chongqing; Sheng, Xinzhi; Shang, Chao; Liu, Lanlan; Wang, Jian

2015-09-01

An optical code division multiple access (OCDMA) secure communications system scheme with rapid reconfigurable polarization shift key (Pol-SK) bipolar user code is proposed and demonstrated. Compared to fix code OCDMA, by constantly changing the user code, the performance of anti-eavesdropping is greatly improved. The Pol-SK OCDMA experiment with a 10 Gchip/s user code and a 1.25 Gb/s user data of payload has been realized, which means this scheme has better tolerance and could be easily realized.

Iterative Pilot-Layer Aided Channel Estimation with Emphasis on Interleave-Division Multiple Access Systems

Directory of Open Access Journals (Sweden)

Schoeneich Hendrik

2006-01-01

Full Text Available Channel estimation schemes suitable for interleave-division multiple access (IDMA systems are presented. Training and data are superimposed. Training-based and semiblind linear channel estimators are derived and their performance is discussed and compared. Monte Carlo simulation results are presented showing that the derived channel estimators in conjunction with a superimposed pilot sequence and chip-by-chip processing are able to track fast-fading frequency-selective channels. As opposed to conventional channel estimation techniques, the BER performance even improves with increasing Doppler spread for typical system parameters. An error performance close to the case of perfect channel knowledge can be achieved with high power efficiency.

A New Prime Code for Synchronous Optical Code Division Multiple-Access Networks

Directory of Open Access Journals (Sweden)

Huda Saleh Abbas

2018-01-01

Full Text Available A new spreading code based on a prime code for synchronous optical code-division multiple-access networks that can be used in monitoring applications has been proposed. The new code is referred to as “extended grouped new modified prime code.” This new code has the ability to support more terminal devices than other prime codes. In addition, it patches subsequences with “0s” leading to lower power consumption. The proposed code has an improved cross-correlation resulting in enhanced BER performance. The code construction and parameters are provided. The operating performance, using incoherent on-off keying modulation and incoherent pulse position modulation systems, has been analyzed. The performance of the code was compared with other prime codes. The results demonstrate an improved performance, and a BER floor of 10−9 was achieved.

Source coherence impairments in a direct detection direct sequence optical code-division multiple-access system.

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Fsaifes, Ihsan; Lepers, Catherine; Lourdiane, Mounia; Gallion, Philippe; Beugin, Vincent; Guignard, Philippe

2007-02-01

We demonstrate that direct sequence optical code- division multiple-access (DS-OCDMA) encoders and decoders using sampled fiber Bragg gratings (S-FBGs) behave as multipath interferometers. In that case, chip pulses of the prime sequence codes generated by spreading in time-coherent data pulses can result from multiple reflections in the interferometers that can superimpose within a chip time duration. We show that the autocorrelation function has to be considered as the sum of complex amplitudes of the combined chip as the laser source coherence time is much greater than the integration time of the photodetector. To reduce the sensitivity of the DS-OCDMA system to the coherence time of the laser source, we analyze the use of sparse and nonperiodic quadratic congruence and extended quadratic congruence codes.

Source coherence impairments in a direct detection direct sequence optical code-division multiple-access system

Science.gov (United States)

Fsaifes, Ihsan; Lepers, Catherine; Lourdiane, Mounia; Gallion, Philippe; Beugin, Vincent; Guignard, Philippe

2007-02-01

We demonstrate that direct sequence optical code- division multiple-access (DS-OCDMA) encoders and decoders using sampled fiber Bragg gratings (S-FBGs) behave as multipath interferometers. In that case, chip pulses of the prime sequence codes generated by spreading in time-coherent data pulses can result from multiple reflections in the interferometers that can superimpose within a chip time duration. We show that the autocorrelation function has to be considered as the sum of complex amplitudes of the combined chip as the laser source coherence time is much greater than the integration time of the photodetector. To reduce the sensitivity of the DS-OCDMA system to the coherence time of the laser source, we analyze the use of sparse and nonperiodic quadratic congruence and extended quadratic congruence codes.

Performance analysis of 2D asynchronous hard-limiting optical code-division multiple access system through atmospheric scattering channel

Science.gov (United States)

Zhao, Yaqin; Zhong, Xin; Wu, Di; Zhang, Ye; Ren, Guanghui; Wu, Zhilu

2013-09-01

Optical code-division multiple access (OCDMA) systems usually allocate orthogonal or quasi-orthogonal codes to the active users. When transmitting through atmospheric scattering channel, the coding pulses are broadened and the orthogonality of the codes is worsened. In truly asynchronous case, namely both the chips and the bits are asynchronous among each active user, the pulse broadening affects the system performance a lot. In this paper, we evaluate the performance of a 2D asynchronous hard-limiting wireless OCDMA system through atmospheric scattering channel. The probability density function of multiple access interference in truly asynchronous case is given. The bit error rate decreases as the ratio of the chip period to the root mean square delay spread increases and the channel limits the bit rate to different levels when the chip period varies.

Diagonal Eigenvalue Unity (DEU) code for spectral amplitude coding-optical code division multiple access

Science.gov (United States)

Ahmed, Hassan Yousif; Nisar, K. S.

2013-08-01

Code with ideal in-phase cross correlation (CC) and practical code length to support high number of users are required in spectral amplitude coding-optical code division multiple access (SAC-OCDMA) systems. SAC systems are getting more attractive in the field of OCDMA because of its ability to eliminate the influence of multiple access interference (MAI) and also suppress the effect of phase induced intensity noise (PIIN). In this paper, we have proposed new Diagonal Eigenvalue Unity (DEU) code families with ideal in-phase CC based on Jordan block matrix with simple algebraic ways. Four sets of DEU code families based on the code weight W and number of users N for the combination (even, even), (even, odd), (odd, odd) and (odd, even) are constructed. This combination gives DEU code more flexibility in selection of code weight and number of users. These features made this code a compelling candidate for future optical communication systems. Numerical results show that the proposed DEU system outperforms reported codes. In addition, simulation results taken from a commercial optical systems simulator, Virtual Photonic Instrument (VPI™) shown that, using point to multipoint transmission in passive optical network (PON), DEU has better performance and could support long span with high data rate.

Constructing a two bands optical code-division multiple-access network of bipolar optical access codecs using Walsh-coded liquid crystal modulators

Science.gov (United States)

Yen, Chih-Ta; Huang, Jen-Fa; Chih, Ping-En

2014-08-01

We propose and experimentally demonstrated the two bands optical code-division multiple-access (OCDMA) network over bipolar Walsh-coded liquid-crystal modulators (LCMs) and driven by green light and red light lasers. Achieving system performance depends on the construction of a decoder that implements a true bipolar correlation using only unipolar signals and intensity detection for each band. We took advantage of the phase delay characteristics of LCMs to construct a prototype optical coder/decoder (codec). Matched and unmatched Walsh signature codes were evaluated to detect correlations among multiuser data in the access network. By using LCMs, a red and green laser light source was spectrally encoded and the summed light dots were complementary decoded. Favorable contrast on auto- and cross-correlations indicates that binary information symbols can be properly recovered using a balanced photodetector.

Multiple Access Techniques for Next Generation Wireless: Recent Advances and Future Perspectives

Directory of Open Access Journals (Sweden)

Shree Krishna Sharma

2016-01-01

Full Text Available The advances in multiple access techniques has been one of the key drivers in moving from one cellular generation to another. Starting from the first generation, several multiple access techniques have been explored in different generations and various emerging multiplexing/multiple access techniques are being investigated for the next generation of cellular networks. In this context, this paper first provides a detailed review on the existing Space Division Multiple Access (SDMA related works. Subsequently, it highlights the main features and the drawbacks of various existing and emerging multiplexing/multiple access techniques. Finally, we propose a novel concept of clustered orthogonal signature division multiple access for the next generation of cellular networks. The proposed concept envisions to employ joint antenna coding in order to enhance the orthogonality of SDMA beams with the objective of enhancing the spectral efficiency of future cellular networks.

Fiber Bragg grating for spectral phase optical code-division multiple-access encoding and decoding

Science.gov (United States)

Fang, Xiaohui; Wang, Dong-Ning; Li, Shichen

2003-08-01

A new method for realizing spectral phase optical code-division multiple-access (OCDMA) coding based on step chirped fiber Bragg gratings (SCFBGs) is proposed and the corresponding encoder/decoder is presented. With this method, a mapping code is introduced for the m-sequence address code and the phase shift can be inserted into the subgratings of the SCFBG according to the mapping code. The transfer matrix method together with Fourier transform is used to investigate the characteristics of the encoder/decoder. The factors that influence the correlation property of the encoder/decoder, including index modulation and bandwidth of the subgrating, are identified. The system structure is simple and good correlation output can be obtained. The performance of the OCDMA system based on SCFBGs has been analyzed.

Performance analysis of spectral-phase-encoded optical code-division multiple-access system regarding the incorrectly decoded signal as a nonstationary random process

Science.gov (United States)

Yan, Meng; Yao, Minyu; Zhang, Hongming

2005-11-01

The performance of a spectral-phase-encoded (SPE) optical code-division multiple-access (OCDMA) system is analyzed. Regarding the incorrectly decoded signal (IDS) as a nonstationary random process, we derive a novel probability distribution for it. The probability distribution of the IDS is considered a chi-squared distribution with degrees of freedom r=1, which is more reasonable and accurate than in previous work. The bit error rate (BER) of an SPE OCDMA system under multiple-access interference is evaluated. Numerical results show that the system can sustain very low BER even when there are multiple simultaneous users, and as the code length becomes longer or the initial pulse becomes shorter, the system performs better.

Adaptive Code Division Multiple Access Protocol for Wireless Network-on-Chip Architectures

Science.gov (United States)

Vijayakumaran, Vineeth

Massive levels of integration following Moore's Law ushered in a paradigm shift in the way on-chip interconnections were designed. With higher and higher number of cores on the same die traditional bus based interconnections are no longer a scalable communication infrastructure. On-chip networks were proposed enabled a scalable plug-and-play mechanism for interconnecting hundreds of cores on the same chip. Wired interconnects between the cores in a traditional Network-on-Chip (NoC) system, becomes a bottleneck with increase in the number of cores thereby increasing the latency and energy to transmit signals over them. Hence, there has been many alternative emerging interconnect technologies proposed, namely, 3D, photonic and multi-band RF interconnects. Although they provide better connectivity, higher speed and higher bandwidth compared to wired interconnects; they also face challenges with heat dissipation and manufacturing difficulties. On-chip wireless interconnects is one other alternative proposed which doesn't need physical interconnection layout as data travels over the wireless medium. They are integrated into a hybrid NOC architecture consisting of both wired and wireless links, which provides higher bandwidth, lower latency, lesser area overhead and reduced energy dissipation in communication. However, as the bandwidth of the wireless channels is limited, an efficient media access control (MAC) scheme is required to enhance the utilization of the available bandwidth. This thesis proposes using a multiple access mechanism such as Code Division Multiple Access (CDMA) to enable multiple transmitter-receiver pairs to send data over the wireless channel simultaneously. It will be shown that such a hybrid wireless NoC with an efficient CDMA based MAC protocol can significantly increase the performance of the system while lowering the energy dissipation in data transfer. In this work it is shown that the wireless NoC with the proposed CDMA based MAC protocol

A Unified Framework of the Performance Evaluation of Optical Time-Wavelength Code-Division Multiple-Access Systems

Science.gov (United States)

Inaty, Elie

In this paper, we provide an analysis to the performance of optical time-wavelength code-division multiple-access (OTW-CDMA) network when the system is working above the nominal transmission rate limit imposed by the passive encoding-decoding operation. We address the problem of overlapping in such a system and how it can directly affect the bit error rate (BER). A unified mathematical framework is presented under the assumption of one coincidence sequences with non-repeating wavelengths. A closed form expression of the multiple access interference limited BER is provided as a function of different system parameters. Results show that the performance of OTW-CDMA system may be critically affected when working above the nominal limit; an event that may happen when the network operates at high transmission rate. In addition, the impact of the derived error probability on the performance of two newly proposed MAC protocols, the S-ALOHA and the R3T, is also investigated. It is shown that for low transmission rates, the S-ALOHA is better than the R3T; while the R3T is better at very high transmission rates. However, in general it is postulated that the R3T protocol suffers a higher delay mainly because of the presence of additional modes.

Effect of beat noise on the performance of two-dimensional time-spreading/wavelength-hopping optical code-division multiple-access systems

Science.gov (United States)

Bazan, T.; Harle, D.; Andonovic, I.; Meenakshi, M.

2005-03-01

The effect of beat noise on optical code-division multiple-access (OCDMA) systems using a range of two-dimensional (2-D) time-spreading/wavelength-hopping (TW) code families is presented. A derivation of a general formula for the error probability of the system is given. The properties of the 2-D codes--namely, the structure, length, and cross-correlation characteristics--are found to have a great influence on system performance. Improved performance can be obtained by use of real-time dynamic thresholding.

Securing optical code-division multiple-access networks with a postswitching coding scheme of signature reconfiguration

Science.gov (United States)

Huang, Jen-Fa; Meng, Sheng-Hui; Lin, Ying-Chen

2014-11-01

The optical code-division multiple-access (OCDMA) technique is considered a good candidate for providing optical layer security. An enhanced OCDMA network security mechanism with a pseudonoise (PN) random digital signals type of maximal-length sequence (M-sequence) code switching to protect against eavesdropping is presented. Signature codes unique to individual OCDMA-network users are reconfigured according to the register state of the controlling electrical shift registers. Examples of signature reconfiguration following state switching of the controlling shift register for both the network user and the eavesdropper are numerically illustrated. Dynamically changing the PN state of the shift register to reconfigure the user signature sequence is shown; this hinders eavesdroppers' efforts to decode correct data sequences. The proposed scheme increases the probability of eavesdroppers committing errors in decoding and thereby substantially enhances the degree of an OCDMA network's confidentiality.

Performance analysis for a chaos-based code-division multiple access system in wide-band channel

Directory of Open Access Journals (Sweden)

Ciprian Doru Giurcăneanu

2015-08-01

Full Text Available Code-division multiple access technology is widely used in telecommunications and its performance has been extensively investigated in the past. Theoretical results for the case of wide-band transmission channel were not available until recently. The novel formulae which have been published in 2014 can have an important impact on the future of wireless multiuser communications, but limitations come from the Gaussian approximations used in their derivation. In this Letter, the authors obtain more accurate expressions of the bit error rate (BER for the case when the model of the wide-band channel is two-ray, with Rayleigh fading. In the authors’ approach, the spreading sequences are assumed to be generated by logistic map given by Chebyshev polynomial function of order two. Their theoretical and experimental results show clearly that the previous results on BER, which rely on the crude Gaussian approximation, are over-pessimistic.

A design of a wavelength-hopping time-spreading incoherent optical code division multiple access system

International Nuclear Information System (INIS)

Glesk, I.; Baby, V.

2005-01-01

We present the architecture and code design for a highly scalable, 2.5 Gb/s per user optical code division multiple access (OCDMA) system. The system is scalable to 100 potential and more than 10 simultaneous users, each with a bit error rate (BER) of less than 10 -9 . The system architecture uses a fast wavelength-hopping, time-spreading codes. Unlike frequency and phase sensitive coherent OCDMA systems, this architecture utilizes standard on off keyed optical pulses allocated in the time and wavelength dimensions. This incoherent OCDMA approach is compatible with existing WDM optical networks and utilizes off the shelf components. We discuss the novel optical subsystem design for encoders and decoders that enable the realization of a highly scalable incoherent OCDMA system with rapid reconfigurability. A detailed analysis of the scalability of the two dimensional code is presented and select network deployment architectures for OCDMA are discussed (Authors)

Comparison of a Ring On-Chip Network and a Code-Division Multiple-Access On-Chip Network

Directory of Open Access Journals (Sweden)

Xin Wang

2007-01-01

Full Text Available Two network-on-chip (NoC designs are examined and compared in this paper. One design applies a bidirectional ring connection scheme, while the other design applies a code-division multiple-access (CDMA connection scheme. Both of the designs apply globally asynchronous locally synchronous (GALS scheme in order to deal with the issue of transferring data in a multiple-clock-domain environment of an on-chip system. The two NoC designs are compared with each other by their network structures, data transfer principles, network node structures, and their asynchronous designs. Both the synchronous and the asynchronous designs of the two on-chip networks are realized using a hardware-description language (HDL in order to make the entire designs suit the commonly used synchronous design tools and flow. The performance estimation and comparison of the two NoC designs which are based on the HDL realizations are addressed. By comparing the two NoC designs, the advantages and disadvantages of applying direct connection and CDMA connection schemes in an on-chip communication network are discussed.

Reduced feedback selective cluster index scheduling with user pre-selection for next-generation multi-input multi-output orthogonal frequency division multiple access system

OpenAIRE

Nicolaou, M; Doufexi, A; Armour, SMD; Sun, Y

2011-01-01

The joint use of opportunistic scheduling and orthogonal frequency division multiple access (OFDMA) provide significant gains in environments of low mobility and scatter for which channel variations are low. The downside of opportunistic scheduling in multicarrier systems such as OFDMA, lies in the substantial uplink overhead required to feed back by the mobile stations (MSs) describing users' instantaneous link conditions. This study presents a novel approach towards multicarrier opportunist...

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

Science.gov (United States)

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

2014-12-01

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

Optical orthogonal code-division multiple-access system - Part 2: Multibits/sequence-period OOCDMA

Science.gov (United States)

Kwon, Hyuck M.

1994-08-01

In a recently proposed optical orthogonal code division multiple-access (OOCDMA) system, one bit of user's data is transmitted per sequence-period, and a threshold is employed for the final bit decision. In this paper, a system that can transmit multibits per sequence-period is introduced, and avalanche photodiode (APD) noise, thermal noise, and interference, are included. This system, derived by exploiting orthogonal properties of the OOCDMA code sequence and using a maximum search (instead of a threshold) in the final decision, is log(sub 2) F times higher in throughput, where F is sequence-period. For example, four orders of magnitude are better in bit error probability at - 56 dBW received laser power, with F = 1000 chips, 10 'marks' in a sequence, and 10 users of 30 Mb/s data rate for one-bit/sequence-period and 270 Mb/s data rate for multibits/sequence-period system. Furthermore, an exact analysis is performed for the log(sub 2)F bits/sequence-period system with a hard-limiter placed before the receiver, and its performance is compared to the performance without hard-limiter, for the chip-synchronous case. The improvement from using a hard-limiter is significant in the log(sub 2)F bits/sequence-period OCCDMA system.

Performance enhancement of successive interference cancellation scheme based on spectral amplitude coding for optical code-division multiple-access systems using Hadamard codes

Science.gov (United States)

Eltaif, Tawfig; Shalaby, Hossam M. H.; Shaari, Sahbudin; Hamarsheh, Mohammad M. N.

2009-04-01

A successive interference cancellation scheme is applied to optical code-division multiple-access (OCDMA) systems with spectral amplitude coding (SAC). A detailed analysis of this system, with Hadamard codes used as signature sequences, is presented. The system can easily remove the effect of the strongest signal at each stage of the cancellation process. In addition, simulation of the prose system is performed in order to validate the theoretical results. The system shows a small bit error rate at a large number of active users compared to the SAC OCDMA system. Our results reveal that the proposed system is efficient in eliminating the effect of the multiple-user interference and in the enhancement of the overall performance.

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

Science.gov (United States)

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

2016-10-01

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

Primary user localisation and uplink resource allocation in orthogonal frequency division multiple access cognitive radio systems

KAUST Repository

Nam, Haewoon

2015-05-21

In cognitive radio networks, secondary users (SUs) can share spectrum with primary users (PUs) under the condition that no interference is caused to the PUs. To evaluate the interference imposed to the PUs, the cognitive systems discussed in the literature usually assume that the channel state information (CSI) of the link from a secondary transmitter to a primary receiver (interference link) is known at the secondary transmitter. However, this assumption may often be impractical in cognitive radio systems, since the PUs need to be oblivious to the presence of the SUs. The authors first discuss PU localisation and then introduce an uplink resource allocation algorithm for orthogonal frequency division multiple access-based cognitive radio systems, where relative location information between primary and SUs is used instead of CSI of the interference link to estimate the interference. Numerical and simulation results show that it is indeed effective to use location information as a part of resource allocation and thus a near-optimal capacity is achieved. © The Institution of Engineering and Technology 2015.

Trellis Tone Modulation Multiple-Access for Peer Discovery in D2D Networks

Directory of Open Access Journals (Sweden)

Chiwoo Lim

2018-04-01

Full Text Available In this paper, a new non-orthogonal multiple-access scheme, trellis tone modulation multiple-access (TTMMA, is proposed for peer discovery of distributed device-to-device (D2D communication. The range and capacity of discovery are important performance metrics in peer discovery. The proposed trellis tone modulation uses single-tone transmission and achieves a long discovery range due to its low Peak-to-Average Power Ratio (PAPR. The TTMMA also exploits non-orthogonal resource assignment to increase the discovery capacity. For the multi-user detection of superposed multiple-access signals, a message-passing algorithm with supplementary schemes are proposed. With TTMMA and its message-passing demodulation, approximately 1.5 times the number of devices are discovered compared to the conventional frequency division multiple-access (FDMA-based discovery.

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

Science.gov (United States)

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.

Environmental Research Division's Data Access Program (ERDDAP)

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National Oceanic and Atmospheric Administration, Department of Commerce — ERDDAP (the Environmental Research Division's Data Access Program) is a data server that gives you a simple, consistent way to download subsets of scientific...

On the interrelation of multiplication and division in secondary school children

Directory of Open Access Journals (Sweden)

Stefan eHuber

2013-10-01

Full Text Available Multiplication and division are conceptually inversely related: Each division problem can be transformed into as a multiplication problem and vice versa. Recent research has indicated strong developmental parallels between multiplication and division in primary school children. In this study, we were interested in (i whether these developmental parallels persist into secondary school, (ii whether similar developmental parallels can be observed for simple and complex problems, (iii whether skill level modulates this relationship, and (iv whether the correlations are specific and not driven by general cognitive or arithmetic abilities.Therefore, we assessed performance of 5th and 6th graders attending two secondary school types of the German educational system in simple and complex multiplication as well as division while controlling for nonverbal intelligence, short-term memory, and other arithmetic abilities. Accordingly, we collected data from students differing in skills levels due to either age (5th and 6th grade or school type (general and intermediate secondary school.We observed moderate to strong bivariate and partial correlations between multiplication and division with correlations being higher for simple tasks but nevertheless reliable for complex tasks. Moreover, the association between simple multiplication and division depended on students’ skill levels as reflected by school types, but not by age. Partial correlations were higher for intermediate than for general secondary school children.In sum, these findings emphasize the importance of the inverse relationship between multiplication and division which persists into later developmental stages. However, evidence for skill-related differences in the relationship between multiplication and division was restricted to the differences for school types.

Spatial-phase code-division multiple-access system with multiplexed Fourier holography switching for reconfigurable optical interconnection

Science.gov (United States)

Takasago, Kazuya; Takekawa, Makoto; Shirakawa, Atsushi; Kannari, Fumihiko

2000-05-01

A new, to our knowledge, space-variant optical interconnection system based on a spatial-phase code-division multiple-access technique with multiplexed Fourier holography is described. In this technique a signal beam is spread over wide spatial frequencies by an M -sequence pseudorandom phase code. At a receiver side a selected signal beam is properly decoded, and at the same time its spatial pattern is shaped with a Fourier hologram, which is recorded by light that is encoded with the same M -sequence phase mask as the desired signal beam and by light whose spatial beam pattern is shaped to a signal routing pattern. Using the multiplexed holography, we can simultaneously route multisignal flows into individually specified receiver elements. The routing pattern can also be varied by means of switching the encoding phase code or replacing the hologram. We demonstrated a proof-of-principle experiment with a doubly multiplexed hologram that enables simultaneous routing of two signal beams. Using a numerical model, we showed that the proposed scheme can manage more than 250 routing patterns for one signal flow with one multiplexed hologram at a signal-to-noise ratio of 5.

Design and simulations of a spectral efficient optical code division multiple access scheme using alternated energy differentiation and single-user soft-decision demodulation

Science.gov (United States)

A. Garba, Aminata

2017-01-01

This paper presents a new approach to optical Code Division Multiple Access (CDMA) network transmission scheme using alternated amplitude sequences and energy differentiation at the transmitters to allow concurrent and secure transmission of several signals. The proposed system uses error control encoding and soft-decision demodulation to reduce the multi-user interference at the receivers. The design of the proposed alternated amplitude sequences, the OCDMA energy modulators and the soft decision, single-user demodulators are also presented. Simulation results show that the proposed scheme allows achieving spectral efficiencies higher than several reported results for optical CDMA and much higher than the Gaussian CDMA capacity limit.

28 CFR 16.74 - Exemption of National Security Division Systems-limited access.

Science.gov (United States)

2010-07-01

... National Security Division Systems—limited access. (a) The following system of records is exempted from... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Exemption of National Security Division Systems-limited access. 16.74 Section 16.74 Judicial Administration DEPARTMENT OF JUSTICE PRODUCTION OR...

A Role for Attentional Reorienting During Approximate Multiplication and Division

Directory of Open Access Journals (Sweden)

Curren Katz

2017-12-01

Full Text Available When asked to estimate the outcome of arithmetic problems, participants overestimate for addition problems and underestimate for subtraction problems, both in symbolic and non-symbolic format. This bias is referred to as operational momentum effect (OM. The attentional shifts account holds that during computation of the outcome participants are propelled too far along a spatial number representation. OM was observed in non-symbolic multiplication and division while being absent in symbolic multiplication and division. Here, we investigate whether (a the absence of the OM in symbolic multiplication and division was due to the presentation of the correct outcome amongst the response alternatives, putatively triggering verbally mediated fact retrieval, and whether (b OM is correlated with attentional parameters, as stipulated by the attentional account. Participants were presented with symbolic and non-symbolic multiplication and division problems. Among seven incorrect response alternatives participants selected the most plausible result. Participants were also presented with a Posner task, with valid (70%, invalid (15% and neutral (15% cues pointing to the position at which a subsequent target would appear. While no OM was observed in symbolic format, non-symbolic problems were subject to OM. The non-symbolic OM was positively correlated with reorienting after invalid cues. These results provide further evidence for a functional association between spatial attention and approximate arithmetic, as stipulated by the attentional shifts account of OM. They also suggest that the cognitive processes underlying multiplication and division are less prone to spatial biases compared to addition and subtraction, further underlining the involvement of differential cognitive processes.

Secure Communications in High Speed Fiber Optical Networks Using Code Division Multiple Access (CDMA) Transmission

Energy Technology Data Exchange (ETDEWEB)

Han, I; Bond, S; Welty, R; Du, Y; Yoo, S; Reinhardt, C; Behymer, E; Sperry, V; Kobayashi, N

2004-02-12

This project is focused on the development of advanced components and system technologies for secure data transmission on high-speed fiber optic data systems. This work capitalizes on (1) a strong relationship with outstanding faculty at the University of California-Davis who are experts in high speed fiber-optic networks, (2) the realization that code division multiple access (CDMA) is emerging as a bandwidth enhancing technique for fiber optic networks, (3) the realization that CDMA of sufficient complexity forms the basis for almost unbreakable one-time key transmissions, (4) our concepts for superior components for implementing CDMA, (5) our expertise in semiconductor device processing and (6) our Center for Nano and Microtechnology, which is where the majority of the experimental work was done. Here we present a novel device concept, which will push the limits of current technology, and will simultaneously solve system implementation issues by investigating new state-of-the-art fiber technologies. This will enable the development of secure communication systems for the transmission and reception of messages on deployed commercial fiber optic networks, through the CDMA phase encoding of broad bandwidth pulses. CDMA technology has been developed as a multiplexing technology, much like wavelength division multiplexing (WDM) or time division multiplexing (TDM), to increase the potential number of users on a given communication link. A novel application of the techniques created for CDMA is to generate secure communication through physical layer encoding. Physical layer encoding devices are developed which utilize semiconductor waveguides with fast carrier response times to phase encode spectral components of a secure signal. Current commercial technology, most commonly a spatial light modulator, allows phase codes to be changed at rates of only 10's of Hertz ({approx}25ms response). The use of fast (picosecond to nanosecond) carrier dynamics of semiconductors

Adaptation of AMO-FBMC-OQAM in optical access network for accommodating asynchronous multiple access in OFDM-based uplink transmission

Science.gov (United States)

Jung, Sun-Young; Jung, Sang-Min; Han, Sang-Kook

2015-01-01

Exponentially expanding various applications in company with proliferation of mobile devices make mobile traffic exploded annually. For future access network, bandwidth efficient and asynchronous signals converged transmission technique is required in optical network to meet a huge bandwidth demand, while integrating various services and satisfying multiple access in perceived network resource. Orthogonal frequency division multiplexing (OFDM) is highly bandwidth efficient parallel transmission technique based on orthogonal subcarriers. OFDM has been widely studied in wired-/wireless communication and became a Long term evolution (LTE) standard. Consequently, OFDM also has been actively researched in optical network. However, OFDM is vulnerable frequency and phase offset essentially because of its sinc-shaped side lobes, therefore tight synchronism is necessary to maintain orthogonality. Moreover, redundant cyclic prefix (CP) is required in dispersive channel. Additionally, side lobes act as interference among users in multiple access. Thus, it practically hinders from supporting integration of various services and multiple access based on OFDM optical transmission In this paper, adaptively modulated optical filter bank multicarrier system with offset QAM (AMO-FBMC-OQAM) is introduced and experimentally investigated in uplink optical transmission to relax multiple access interference (MAI), while improving bandwidth efficiency. Side lobes are effectively suppressed by using FBMC, therefore the system becomes robust to path difference and imbalance among optical network units (ONUs), which increase bandwidth efficiency by reducing redundancy. In comparison with OFDM, a signal performance and an efficiency of frequency utilization are improved in the same experimental condition. It enables optical network to effectively support heterogeneous services and multiple access.

Stationary Size Distributions of Growing Cells with Binary and Multiple Cell Division

Science.gov (United States)

Rading, M. M.; Engel, T. A.; Lipowsky, R.; Valleriani, A.

2011-10-01

Populations of unicellular organisms that grow under constant environmental conditions are considered theoretically. The size distribution of these cells is calculated analytically, both for the usual process of binary division, in which one mother cell produces always two daughter cells, and for the more complex process of multiple division, in which one mother cell can produce 2 n daughter cells with n=1,2,3,… . The latter mode of division is inspired by the unicellular algae Chlamydomonas reinhardtii. The uniform response of the whole population to different environmental conditions is encoded in the individual rates of growth and division of the cells. The analytical treatment of the problem is based on size-dependent rules for cell growth and stochastic transition processes for cell division. The comparison between binary and multiple division shows that these different division processes lead to qualitatively different results for the size distribution and the population growth rates.

Joint power control based on service factor for code division multiple access system%TDD-CDMA系统中基于业务统计的联合功率控制算法

Institute of Scientific and Technical Information of China (English)

陈波; 戎蒙恬; 胡威

2008-01-01

An important feature of the traffic in mobile networks is burstiness. Drawbacks of conventional power control algorithms for time division duplex (TDD)-code division multiple access (CDMA) systems are analyzed. A joint power control algorithm based on service factor is presented to address the TDD-CDMA mobile services in the burst mode according to the Markov modulated Bernoulli process. The joint power control equation is derived. A function model is developed to verify the new algorithm and evaluate its performance. Simulation results show that the new power control algorithm can estimate interference strength more precisely, speed up convergence of power control, and enhance power efficiency and system capacity. It is shown that the proposed algorithm is more robust against rink gain changes, and outperforms the reference algorithms.

Dispersion-flattened-fiber based optical thresholder for multiple-access-interference suppression in OCDMA system.

Science.gov (United States)

Wang, Xu; Hamanaka, Taro; Wada, Naoya; Kitayama, Ken-Ichi

2005-07-11

An optical thresholding technique based on super-continuum generation in dispersion flattened fiber is proposed and experimentally demonstrated to enable data-rate detection in optical code division multiple access networks. The proposed scheme exhibits an excellent discrimination between a desired signal and interference signals with features of pulse reshaping, low insertion loss, polarization independency as well as reasonable operation power.

A Design Study to Develop Young Children's Understanding of Multiplication and Division

Science.gov (United States)

Bicknell, Brenda; Young-Loveridge, Jenny; Nguyen, Nhung

2016-01-01

This design study investigated the use of multiplication and division problems to help 5-year-old children develop an early understanding of multiplication and division. One teacher and her class of 15 5-year-old children were involved in a collaborative partnership with the researchers. The design study was conducted over two 4-week periods in…

Demonstration of two-user, 10-Gbits/s optical code-division multiple-access system implemented by using cascaded longperiod fiber gratings formed in dispersion-compensating fiber with inner-cladding structure

DEFF Research Database (Denmark)

Kim, Sun-Jong; Eom, T.J.; Kim, T.Y.

2005-01-01

A two-user, 10-Gbits/s optical code-division multiple-access system implemented by using cascaded long-period fiber gratings formed in a dispersion-compensating fiber (DCF) is demonstrated. Our results show that the sensitivity of cladding modes to the refractive index change on the cladding...... surface is greatly reduced by utilizing the inner-cladding mode of the DCF. Two pairs of encoder/decoder are constructed and the performance is evaluated by measuring bit error rate (BER). With an interferer, a BER of 1.5 X 10(-12) is measured at a received optical power of -6 dBm....

Novel secure and bandwidth efficient optical code division multiplexed system for future access networks

Science.gov (United States)

Singh, Simranjit

2016-12-01

In this paper, a spectrally coded optical code division multiple access (OCDMA) system using a hybrid modulation scheme has been investigated. The idea is to propose an effective approach for simultaneous improvement of the system capacity and security. Data formats, NRZ (non-return to zero), DQPSK (differential quadrature phase shift keying), and PoISk (polarisation shift keying) are used to get the orthogonal modulated signal. It is observed that the proposed hybrid modulation provides efficient utilisation of bandwidth, increases the data capacity and enhances the data confidentiality over existing OCDMA systems. Further, the proposed system performance is compared with the current state-of-the-art OCDMA schemes.

Demonstration of two-user, 10-Gbits/s optical code-division multiple-access system implemented by using cascaded long-period fiber gratings formed in dispersion-compensating fiber with inner-cladding structure

Science.gov (United States)

Kim, Sun-Jong; Eom, Tae-Jung; Kim, Tae-Young; Lee, Byeong Ha; Park, Chang-Soo

2005-09-01

A two-user, 10-Gbits/s optical code-division multiple-access system implemented by using cascaded long-period fiber gratings formed in a dispersion-compensating fiber (DCF) is demonstrated. Our results show that the sensitivity of cladding modes to the refractive index change on the cladding surface is greatly reduced by utilizing the inner-cladding mode of the DCF. Two pairs of encoder/decoder are constructed and the performance is evaluated by measuring bit error rate (BER). With an interferer, a BER of 1.5×10-12 is measured at a received optical power of -6 dBm.

A distributed Synchronous reservation multiple access control protocol for mobile Ad hoc networks

Institute of Scientific and Technical Information of China (English)

ZHANG Yanling; SUN Xianpu; LI Jiandong

2007-01-01

This study proposes a new multiple access control protocol named distributed synchronous reservation multiple access control protocol.in which the hidden and exposed terminal problems are solved,and the quality of service(QoS)requirements for real-time traffic are guaranteed.The protocol is founded on time division multiplex address and a different type of traffic is assigned to difierent priority,according to which a node should compete for and reserve the free slots in a different method.Moreover,there is a reservation acknowledgement process before data transmit in each reserved slot,so that the intruded terminal problem is solved.The throughput and average packets drop probability of this protocol are analyzed and simulated in a fully connected network.the results of which indicate that this protocol is efficient enough to support the real-time traffic.and it is more suitable to MANETs.

Competing Biases in Mental Arithmetic: When Division Is More and Multiplication Is Less.

Science.gov (United States)

Shaki, Samuel; Fischer, Martin H

2017-01-01

Mental arithmetic exhibits various biases. Among those is a tendency to overestimate addition and to underestimate subtraction outcomes. Does such "operational momentum" (OM) also affect multiplication and division? Twenty-six adults produced lines whose lengths corresponded to the correct outcomes of multiplication and division problems shown in symbolic format. We found a reliable tendency to over-estimate division outcomes, i.e., reverse OM. We suggest that anchoring on the first operand (a tendency to use this number as a reference for further quantitative reasoning) contributes to cognitive biases in mental arithmetic.

Using mini-games for learning multiplication and division: A longitudinal effect study

NARCIS (Netherlands)

Bakker, M.

2014-01-01

This thesis reports the findings of a three-year longitudinal research project set up to investigate the effectiveness of employing online mini-games for the learning of multiplication and division, including multiplicative fact knowledge (declarative knowledge), multiplicative operation skills

Multiple Access Interference Reduction Using Received Response Code Sequence for DS-CDMA UWB System

Science.gov (United States)

Toh, Keat Beng; Tachikawa, Shin'ichi

This paper proposes a combination of novel Received Response (RR) sequence at the transmitter and a Matched Filter-RAKE (MF-RAKE) combining scheme receiver system for the Direct Sequence-Code Division Multiple Access Ultra Wideband (DS-CDMA UWB) multipath channel model. This paper also demonstrates the effectiveness of the RR sequence in Multiple Access Interference (MAI) reduction for the DS-CDMA UWB system. It suggests that by using conventional binary code sequence such as the M sequence or the Gold sequence, there is a possibility of generating extra MAI in the UWB system. Therefore, it is quite difficult to collect the energy efficiently although the RAKE reception method is applied at the receiver. The main purpose of the proposed system is to overcome the performance degradation for UWB transmission due to the occurrence of MAI during multiple accessing in the DS-CDMA UWB system. The proposed system improves the system performance by improving the RAKE reception performance using the RR sequence which can reduce the MAI effect significantly. Simulation results verify that significant improvement can be obtained by the proposed system in the UWB multipath channel models.

2x2 MIMO-OFDM Gigabit fiber-wireless access system based on polarization division multiplexed WDM-PON

DEFF Research Database (Denmark)

Deng, Lei; Pang, Xiaodan; Zhao, Ying

2012-01-01

We propose a spectral efficient radio over wavelength division multiplexed passive optical network (WDM-PON) system by combining optical polarization division multiplexing (PDM) and wireless multiple input multiple output (MIMO) spatial multiplexing techniques. In our experiment, a training-based...

Performance of asynchronous fiber-optic code division multiple access system based on three-dimensional wavelength/time/space codes and its link analysis.

Science.gov (United States)

Singh, Jaswinder

2010-03-10

A novel family of three-dimensional (3-D) wavelength/time/space codes for asynchronous optical code-division-multiple-access (CDMA) systems with "zero" off-peak autocorrelation and "unity" cross correlation is reported. Antipodal signaling and differential detection is employed in the system. A maximum of [(W x T+1) x W] codes are generated for unity cross correlation, where W and T are the number of wavelengths and time chips used in the code and are prime. The conditions for violation of the cross-correlation constraint are discussed. The expressions for number of generated codes are determined for various code dimensions. It is found that the maximum number of codes are generated for S systems. The codes have a code-set-size to code-size ratio greater than W/S. For instance, with a code size of 2065 (59 x 7 x 5), a total of 12,213 users can be supported, and 130 simultaneous users at a bit-error rate (BER) of 10(-9). An arrayed-waveguide-grating-based reconfigurable encoder/decoder design for 2-D implementation for the 3-D codes is presented so that the need for multiple star couplers and fiber ribbons is eliminated. The hardware requirements of the coders used for various modulation/detection schemes are given. The effect of insertion loss in the coders is shown to be significantly reduced with loss compensation by using an amplifier after encoding. An optical CDMA system for four users is simulated and the results presented show the improvement in performance with the use of loss compensation.

High security chaotic multiple access scheme for visible light communication systems with advanced encryption standard interleaving

Science.gov (United States)

Qiu, Junchao; Zhang, Lin; Li, Diyang; Liu, Xingcheng

2016-06-01

Chaotic sequences can be applied to realize multiple user access and improve the system security for a visible light communication (VLC) system. However, since the map patterns of chaotic sequences are usually well known, eavesdroppers can possibly derive the key parameters of chaotic sequences and subsequently retrieve the information. We design an advanced encryption standard (AES) interleaving aided multiple user access scheme to enhance the security of a chaotic code division multiple access-based visible light communication (C-CDMA-VLC) system. We propose to spread the information with chaotic sequences, and then the spread information is interleaved by an AES algorithm and transmitted over VLC channels. Since the computation complexity of performing inverse operations to deinterleave the information is high, the eavesdroppers in a high speed VLC system cannot retrieve the information in real time; thus, the system security will be enhanced. Moreover, we build a mathematical model for the AES-aided VLC system and derive the theoretical information leakage to analyze the system security. The simulations are performed over VLC channels, and the results demonstrate the effectiveness and high security of our presented AES interleaving aided chaotic CDMA-VLC system.

Multiple Access Communications

DEFF Research Database (Denmark)

This book constitutes the proceedings of the 9th International Workshop on Multiple Access Communications, MACOM 2016, held in Aalborg, Denmark, in November 2016. The 10 full papers presented in this volume were carefully reviewed and selected from 12 submissions. They were organized in topical...

Addition and Subtraction but Not Multiplication and Division Cause Shifts of Spatial Attention

Directory of Open Access Journals (Sweden)

Mengjin Li

2018-05-01

Full Text Available Many studies have shown that solving addition and subtraction problems can induce overt shifts of spatial attention. In particular, right-side targets are detected faster than left-side targets when preceded by an addition operation, while left-side targets are detected faster than right-side targets when preceded by a subtraction operation. However, the interaction between space and arithmetic in multiplication or division is hardly studied and remains controversial. In order to make a strong case for the interaction between space and mental arithmetic, we attempted to replicate the spatial-arithmetic association in addition and subtraction (Experiment 1, and at the same time investigated whether shift of spatial attention would also be induced by multiplication or division operations (Experiment 2. We found that solving addition problems facilitated the detection of right-side targets, whereas left-side targets were detected faster after solving subtraction problems. However, no interaction between space and arithmetic operation was observed in multiplication or division. The implication of these findings is discussed.

Fraction Multiplication and Division Word Problems Posed by Different Years of Pre-Service Elementary Mathematics Teachers

Directory of Open Access Journals (Sweden)

Tuba Aydogdu Iskenderoglu

2018-04-01

Full Text Available It is important for pre-service teachers to know the conceptual difficulties they have experienced regarding the concepts of multiplication and division in fractions and problem posing is a way to learn these conceptual difficulties. Problem posing is a synthetic activity that fundamentally has multiple answers. The purpose of this study is to analyze the multiplication and division of fractions problems posed by pre-service elementary mathematics teachers and to investigate how the problems posed change according to the year of study the pre-service teachers are in. The study employed developmental research methods. A total of 213 pre-service teachers enrolled in different years of the Elementary Mathematics Teaching program at a state university in Turkey took part in the study. The “Problem Posing Test” was used as the data collecting tool. In this test, there are 3 multiplication and 3 division operations. The data were analyzed using qualitative descriptive analysis. The findings suggest that, regardless of the year, pre-service teachers had more conceptual difficulties in problem posing about the division of fractions than in problem posing about the multiplication of fractions.

Performance evaluation of modulation and multiple access schemes in ultraviolet optical wireless connections for two atmosphere thickness cases.

Science.gov (United States)

Raptis, Nikos; Pikasis, Evangelos; Syvridis, Dimitris

2016-08-01

The exploitation of optical wireless communication channels in a non-line-of-sight regime is studied for point-to-point and networking configurations considering the use of light-emitting diodes. Two environments with different scattering center densities are considered, assuming operation at 265 nm. The bit error rate performance of both pulsed and multicarrier modulation schemes is examined, using numerical approaches. In the networking scenario, a central node only receives data, one node transmits useful data, and the rest of them act as interferers. The performance of the desirable node's transmissions is evaluated. The access to the medium is controlled by a code division multiple access scheme.

Mixing stream and datagram traffic on satellite: A FIFO Order-based Demand Assignment (FODA) Time Division Multiple Access (TDMA) scheme

Science.gov (United States)

Beltrame, R.; Bonito, A. B.; Celandroni, N.; Ferro, E.

1985-11-01

A FIFO Order based Demand Assignment (FODA) access scheme was designed to handle packetized data and voice traffic in a multiple access satellite broadcast channel of Mbits band. The channel is shared by as many as 64 simultaneously active stations in a range of 255 addressable stations. A sophisticated traffic environment is assumed, including different types of service requirements and an arbitrary load distribution among the stations. The results of 2Mbit/sec simulation tests for an existing hardware environment are presented.

Performance Analysis of Optical Code Division Multiplex System

Science.gov (United States)

Kaur, Sandeep; Bhatia, Kamaljit Singh

2013-12-01

This paper presents the Pseudo-Orthogonal Code generator for Optical Code Division Multiple Access (OCDMA) system which helps to reduce the need of bandwidth expansion and improve spectral efficiency. In this paper we investigate the performance of multi-user OCDMA system to achieve data rate more than 1 Tbit/s.

Delay-limited capacity of fading multiple access and broadcast channels in the low power regime

KAUST Repository

Rezki, Zouheir

2015-09-11

We study delay-limited (also called zero-outage) capacity region of the fading multi-access channel (MAC) with Gaussian noise and perfect channel state information (CSI) at the receiver and at the transmitters (CSI-TR), in the low-power regime. We show that for fading channels where the MAC capacity region is strictly positive, it has a multidimensional rectangle structure and thus is simply characterized by single user capacity points. More specifically, we show that at low power, the boundary surface of the capacity region shrinks to a single point corresponding to the sum-rate maximizer and that the coordinates of this point coincide with single user capacity bounds. Using the duality of the Gaussian MAC and broadcast channels (BC), we show that time-sharing (or time division multiple access (TDMA)) is asymptotically optimal. © 2015 IEEE.

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

Science.gov (United States)

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

2015-12-01

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

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

Directory of Open Access Journals (Sweden)

Mario Manzano

2015-01-01

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

The Relationship Between Problem Size and Fixation Patterns During Addition, Subtraction, Multiplication, and Division

Directory of Open Access Journals (Sweden)

Evan T. Curtis

2016-08-01

Full Text Available Eye-tracking methods have only rarely been used to examine the online cognitive processing that occurs during mental arithmetic on simple arithmetic problems, that is, addition and multiplication problems with single-digit operands (e.g., operands 2 through 9; 2 + 3, 6 x 8 and the inverse subtraction and division problems (e.g., 5 – 3; 48 ÷ 6. Participants (N = 109 solved arithmetic problems from one of the four operations while their eye movements were recorded. We found three unique fixation patterns. During addition and multiplication, participants allocated half of their fixations to the operator and one-quarter to each operand, independent of problem size. The pattern was similar on small subtraction and division problems. However, on large subtraction problems, fixations were distributed approximately evenly across the three stimulus components. On large division problems, over half of the fixations occurred on the left operand, with the rest distributed between the operation sign and the right operand. We discuss the relations between these eye tracking patterns and other research on the differences in processing across arithmetic operations.

Inclusive bit error rate analysis for coherent optical code-division multiple-access system

Science.gov (United States)

Katz, Gilad; Sadot, Dan

2002-06-01

Inclusive noise and bit error rate (BER) analysis for optical code-division multiplexing (OCDM) using coherence techniques is presented. The analysis contains crosstalk calculation of the mutual field variance for different number of users. It is shown that the crosstalk noise depends deeply on the receiver integration time, the laser coherence time, and the number of users. In addition, analytical results of the power fluctuation at the received channel due to the data modulation at the rejected channels are presented. The analysis also includes amplified spontaneous emission (ASE)-related noise effects of in-line amplifiers in a long-distance communication link.

Time-division optical interconnects for local-area and micro-area networks

Science.gov (United States)

Krol, Mark F.; Boncek, Raymond K.; Johns, Steven T.; Stacy, John L.

1991-12-01

This report describes the development of an optical Time-Division Multiple-Access (TDMA) interconnect suitable for applications in local-area and micro-area networks. The advantages of using time-division techniques instead of frequency-division, wavelength-division, or code-division techniques in a shared-medium environment are discussed in detail. Furthermore, a detailed description of the TDMA architecture is presented along with various experiments pertaining to the actual components needed to implement the system. Finally, experimental data is presented for an actual optical TDMA test bed. The experimental data demonstrates the feasibility of the architecture, and shows that currently the system has the capability to accommodate up to 50 channels. The bit-error-rate per channel was measured to be less than 10(exp -9) for pseudo-random bit-sequences.

On board processing for future satellite communications systems: Comparison of FDM, TDM and hybrid accessing schemes

Science.gov (United States)

Berk, G.; Jean, P. N.; Rotholz, E.

1982-01-01

Several satellite uplink and downlink accessing schemes for customer premises service are compared. Four conceptual system designs are presented: satellite-routed frequency division multiple access (FDMA), satellite-switched time division multiple access (TDMA), processor-routed TDMA, and frequency-routed TDMA, operating in the 30/20 GHz band. The designs are compared on the basis of estimated satellite weight, system capacity, power consumption, and cost. The systems are analyzed for fixed multibeam coverage of the continental United States. Analysis shows that the system capacity is limited by the available satellite resources and by the terminal size and cost.

Efficient medium access control protocol for geostationary satellite systems

Institute of Scientific and Technical Information of China (English)

王丽娜; 顾学迈

2004-01-01

This paper proposes an efficient medium access control (MAC) protocol based on multifrequency-time division multiple access (MF-TDMA) for geostationary satellite systems deploying multiple spot-beams and onboard processing,which uses a method of random reservation access with movable boundaries to dynamically request the transmission slots and can transmit different types of traffic. The simulation results have shown that our designed MAC protocol can achieve a high bandwidth utilization, while providing the required quality of service (QoS) for each class of service.

A new access scheme in OFDMA systems

Institute of Scientific and Technical Information of China (English)

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

2006-01-01

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

Upgrade of hybrid fibre coax networks towards bi-directional access

NARCIS (Netherlands)

Khoe, G.D.; Wolters, R.P.C.; Boom, van den H.P.A.; Prati, G.

1997-01-01

In this paper we describe an upgrade scenario for Hybrid Fibre Coax (HFC) CATV Networks towards hi-directional access. The communication system described has been newly designed, and is based on the use of Direct Sequence- Code Division Multiple-Access (DS-CDMA). Due to its spread-spectrum

Coding and decoding for code division multiple user communication systems

Science.gov (United States)

Healy, T. J.

1985-01-01

A new algorithm is introduced which decodes code division multiple user communication signals. The algorithm makes use of the distinctive form or pattern of each signal to separate it from the composite signal created by the multiple users. Although the algorithm is presented in terms of frequency-hopped signals, the actual transmitter modulator can use any of the existing digital modulation techniques. The algorithm is applicable to error-free codes or to codes where controlled interference is permitted. It can be used when block synchronization is assumed, and in some cases when it is not. The paper also discusses briefly some of the codes which can be used in connection with the algorithm, and relates the algorithm to past studies which use other approaches to the same problem.

An algorithm to compute a rule for division problems with multiple references

Directory of Open Access Journals (Sweden)

Sánchez Sánchez, Francisca J.

2012-01-01

Full Text Available In this paper we consider an extension of the classic division problem with claims: Thedivision problem with multiple references. Hinojosa et al. (2012 provide a solution for this type of pro-blems. The aim of this work is to extend their results by proposing an algorithm that calculates allocationsbased on these results. All computational details are provided in the paper.

On the upgrade of an optical code division PON with a code-sense ethernet MAC protocol

NARCIS (Netherlands)

Huiszoon, B.; Waardt, de H.; Khoe, G.D.; Koonen, A.M.J.

2007-01-01

We propose, for the first time, optical code-sense multiple access / collision detection to upgrade an optical code division passive optical network with minor modifications to transparently deploy Ethernet (or packet) based services.

Threshold-Based Multiple Optical Signal Selection Scheme for Free-Space Optical Wavelength Division Multiplexing Systems

KAUST Repository

Nam, Sung Sik; Alouini, Mohamed-Slim; Zhang, Lin; Ko, Young-Chai

2017-01-01

We propose a threshold-based multiple optical signal selection scheme (TMOS) for free-space optical wavelength division multiplexing systems. With this scheme, we can obtain higher spectral efficiency while reducing the possible complexity

Cell Division, a new open access online forum for and from the cell cycle community

Directory of Open Access Journals (Sweden)

Kaldis Philipp

2006-04-01

Full Text Available Abstract Cell Division is a new, open access, peer-reviewed online journal that publishes cutting-edge articles, commentaries and reviews on all exciting aspects of cell cycle control in eukaryotes. A major goal of this new journal is to publish timely and significant studies on the aberrations of the cell cycle network that occur in cancer and other diseases.

Multirate IP traffic transmission in flexible access networks based on optical FFH-CDMA

DEFF Research Database (Denmark)

Raddo, Thiago R.; Sanches, Anderson L.; Tafur Monroy, Idelfonso

2016-01-01

In this paper, we propose a new IP transmission architecture over optical fast frequency hopping code-division multiple-access (OFFH-CDMA) network capable of supporting multirate transmissions for applications in flexible optical access networks. The proposed network architecture is independent...

Gain transient control for wavelength division multiplexed access networks using semiconductor optical amplifiers

DEFF Research Database (Denmark)

Gibbon, Timothy Braidwood; Osadchiy, Alexey Vladimirovich; Kjær, Rasmus

2009-01-01

Gain transients can severely hamper the upstream network performance in wavelength division multiplexed (WDM) access networks featuring erbium doped fiber amplifiers (EDFAs) or Raman amplification. We experimentally demonstrate for the first time using 10 Gb/s fiber transmission bit error rate...... measurements how a near-saturated semiconductor optical amplifier (SOA) can be used to control these gain transients. An SOA is shown to reduce the penalty of transients originating in an EDFA from 2.3 dB to 0.2 dB for 10 Gb/s transmission over standard single mode fiber using a 231-1 PRBS pattern. The results...... suggest that a single SOA integrated within a WDM receiver at the metro node could offer a convenient all-optical solution for upstream transient controlin WDM access networks....

Coupled Multiple-Response versus Free-Response Conceptual Assessment: An Example from Upper-Division Physics

Science.gov (United States)

Wilcox, Bethany R.; Pollock, Steven J.

2014-01-01

Free-response research-based assessments, like the Colorado Upper-division Electrostatics Diagnostic (CUE), provide rich, fine-grained information about students' reasoning. However, because of the difficulties inherent in scoring these assessments, the majority of the large-scale conceptual assessments in physics are multiple choice. To increase…

Stability Properties of Network Diversity Multiple Access with Multiple-Antenna Reception and Imperfect Collision Multiplicity Estimation

Directory of Open Access Journals (Sweden)

Ramiro Samano-Robles

2013-01-01

Full Text Available In NDMA (network diversity multiple access, protocol-controlled retransmissions are used to create a virtual MIMO (multiple-input multiple-output system, where collisions can be resolved via source separation. By using this retransmission diversity approach for collision resolution, NDMA is the family of random access protocols with the highest potential throughput. However, several issues remain open today in the modeling and design of this type of protocol, particularly in terms of dynamic stable performance and backlog delay. This paper attempts to partially fill this gap by proposing a Markov model for the study of the dynamic-stable performance of a symmetrical and non-blind NDMA protocol assisted by a multiple-antenna receiver. The model is useful in the study of stability aspects in terms of the backlog-user distribution and average backlog delay. It also allows for the investigation of the different states of the system and the transition probabilities between them. Unlike previous works, the proposed approach considers the imperfect estimation of the collision multiplicity, which is a crucial process to the performance of NDMA. The results suggest that NDMA improves not only the throughput performance over previous solutions, but also the average number of backlogged users, the average backlog delay and, in general, the stability of random access protocols. It is also shown that when multiuser detection conditions degrade, ALOHA-type backlog retransmission becomes relevant to the stable operation of NDMA.

Fade detector for the FODA-TDMA access scheme

Science.gov (United States)

Celandroni, Nedo; Ferro, Erina; Marzoli, Antonio

1989-05-01

The First in first out Ordered Demand Assignment-Time Division Multiple Access (FODA-TDMA) satellite access scheme designed for simultaneous transmissions of real time data, like packetized voice and slow-scan images (stream traffic) and data coming from standard EDP applications, such as bulk data tansfer, interactive computer access, mailing, data base enquiry and updating (datagram traffic) is described. When deep fades are experienced due to rain attenuation, the system is able to counter the fade. Techniques to detect the fade are presented.

OFDM Towards Fixed and Mobile Broadband Wireless Access

DEFF Research Database (Denmark)

Shanker Jha, Uma; Prasad, Ramjee

) and orthogonal frequency division multiple access (OFDMA) schemes. Essential features of IEEE 802.16d (fixed) and 802.16e (mobile) and the role of the WiMAX Forum in defining interoperability and certification criteria. Important requirements, trade-offs, and other critical design considerations. Key issues...

Feasibility of space-division-multiplexed transmission of IEEE 802.11 n/ac-compliant wireless MIMO signals over OM3 multimode fiber

NARCIS (Netherlands)

Lei, Yi; Li, Jianqiang; Meng, Ziyi; Wu, Rui; Wan, Zhiquan; Fan, Yuting; Zhang, Wenjia; Yin, Feifei; Dai, Yitang; Xu, Kun

2018-01-01

In this paper, we have experimentally demonstrated the feasibility of space-division-multiplexed 3 × 3 multiple-input multiple-output (MIMO) transmission over a single OM3 multimode fiber (MMF) using commercial IEEE 802.11 n/ac access points. Throughput performance for different fiber length links

A Brief Survey of Media Access Control, Data Link Layer, and Protocol Technologies for Lunar Surface Communications

Science.gov (United States)

Wallett, Thomas M.

2009-01-01

This paper surveys and describes some of the existing media access control and data link layer technologies for possible application in lunar surface communications and the advanced wideband Direct Sequence Code Division Multiple Access (DSCDMA) conceptual systems utilizing phased-array technology that will evolve in the next decade. Time Domain Multiple Access (TDMA) and Code Division Multiple Access (CDMA) are standard Media Access Control (MAC) techniques that can be incorporated into lunar surface communications architectures. Another novel hybrid technique that is recently being developed for use with smart antenna technology combines the advantages of CDMA with those of TDMA. The relatively new and sundry wireless LAN data link layer protocols that are continually under development offer distinct advantages for lunar surface applications over the legacy protocols which are not wireless. Also several communication transport and routing protocols can be chosen with characteristics commensurate with smart antenna systems to provide spacecraft communications for links exhibiting high capacity on the surface of the Moon. The proper choices depend on the specific communication requirements.

Eliminating four-wave-mixing crosstalk in wavelength-division-multiplexing systems

Science.gov (United States)

Kwong, Wing C.; Yang, Guu-Chang

1996-11-01

To reduce four-wave-mixing crosstalk in long-haul wavelength-division multiplexing (WDM) lightwave systems, the use of unequally spaced channels has recently been proposed. Instead of being solved y integer linear programming, the unequal-spaced channel-allocation problem is here treated as constructing suitable optical orthogonal codes in optical code-division multiple-access (CDMA). Three 'algebraic' algorithms on finding the frequency locations of unequally spaced WDM channels are reported. The constructions are based on generating optical CDMA codewords with a predetermined pulse separation and 'aperiodic' autocorrelation sidelobes no greater than one. The algorithms potentially provide a fast and simple alternative to solve the problem, besides the recently reported computer-search method.

Las Matematicas: Lenguaje Universal. Nivel 2b: Multiplicacion y Division de Numeros Enteros (Mathematics: A Universal Language. Level 2b: Multiplication and Division of Whole Numbers).

Science.gov (United States)

Dissemination and Assessment Center for Bilingual Education, Austin, TX.

This is one of a series of student booklets designed for use in a bilingual mathematics program in grades 6-8. The general format is to present each page in both Spanish and English. The mathematical topics in this booklet include multiplication and division. (MK)

System Design and Cataloging Meet the User: User Interfaces to Online Public Access Catalogs.

Science.gov (United States)

Yee, Martha M.

1991-01-01

Discusses features of online public access catalogs: (1) demonstration of relationships between records; (2) provision of entry vocabularies; (3) arrangement of multiple entries on the screen; (4) provision of access points; (5) display of single records; and (6) division of catalogs into separate files or indexes. User studies and other research…

Scalable Lunar Surface Networks and Adaptive Orbit Access

Science.gov (United States)

Wang, Xudong

2015-01-01

Teranovi Technologies, Inc., has developed innovative network architecture, protocols, and algorithms for both lunar surface and orbit access networks. A key component of the overall architecture is a medium access control (MAC) protocol that includes a novel mechanism of overlaying time division multiple access (TDMA) and carrier sense multiple access with collision avoidance (CSMA/CA), ensuring scalable throughput and quality of service. The new MAC protocol is compatible with legacy Institute of Electrical and Electronics Engineers (IEEE) 802.11 networks. Advanced features include efficiency power management, adaptive channel width adjustment, and error control capability. A hybrid routing protocol combines the advantages of ad hoc on-demand distance vector (AODV) routing and disruption/delay-tolerant network (DTN) routing. Performance is significantly better than AODV or DTN and will be particularly effective for wireless networks with intermittent links, such as lunar and planetary surface networks and orbit access networks.

Rendering Intelligence at Physical Layer for Smart Addressing and Multiple Access

DEFF Research Database (Denmark)

Sanyal, Rajarshi; Prasad, Ramjee; Cianca, Ernestina

2010-01-01

addressing of a node. For a typical closed user group type of network, we propose a multiple access mechanism and network topology which will not only eliminate the need of intelligent core network equipments in the network area , but to use this intelligent physical layer to directly reach any node over......The primary objective of this work is to propose a technique of wireless communication, where we render intelligence to the physical layer. We aim to realize a physical layer that can take part in some processes which is otherwise confined to higher layer signalling activities, like for example...... the fundamentals behind the proposed multiple access scheme and draws out the benefits compared to the existing multiple access processes based on cellular approach....

High Dimensional Modulation and MIMO Techniques for Access Networks

DEFF Research Database (Denmark)

Binti Othman, Maisara

Exploration of advanced modulation formats and multiplexing techniques for next generation optical access networks are of interest as promising solutions for delivering multiple services to end-users. This thesis addresses this from two different angles: high dimensionality carrierless...... the capacity per wavelength of the femto-cell network. Bit rate up to 1.59 Gbps with fiber-wireless transmission over 1 m air distance is demonstrated. The results presented in this thesis demonstrate the feasibility of high dimensionality CAP in increasing the number of dimensions and their potentially......) optical access network. 2 X 2 MIMO RoF employing orthogonal frequency division multiplexing (OFDM) with 5.6 GHz RoF signaling over all-vertical cavity surface emitting lasers (VCSEL) WDM passive optical networks (PONs). We have employed polarization division multiplexing (PDM) to further increase...

Radio Access Sharing Strategies for Multiple Operators in Cellular Networks

DEFF Research Database (Denmark)

Popovska Avramova, Andrijana; Iversen, Villy Bæk

2015-01-01

deployments (required for coverage enhancement), increased base station utilization, and reduced overall power consumption. Today, network sharing in the radio access part is passive and limited to cell sites. With the introduction of Cloud Radio Access Network and Software Defined Networking adoption...... to the radio access network, the possibility for sharing baseband processing and radio spectrum becomes an important aspect of network sharing. This paper investigates strategies for active sharing of radio access among multiple operators, and analyses the individual benefits depending on the sharing degree...

On infinitely divisible semimartingales

DEFF Research Database (Denmark)

Basse-O'Connor, Andreas; Rosiński, Jan

2015-01-01

to non Gaussian infinitely divisible processes. First we show that the class of infinitely divisible semimartingales is so large that the natural analog of Stricker's theorem fails to hold. Then, as the main result, we prove that an infinitely divisible semimartingale relative to the filtration generated...... by a random measure admits a unique decomposition into an independent increment process and an infinitely divisible process of finite variation. Consequently, the natural analog of Stricker's theorem holds for all strictly representable processes (as defined in this paper). Since Gaussian processes...... are strictly representable due to Hida's multiplicity theorem, the classical Stricker's theorem follows from our result. Another consequence is that the question when an infinitely divisible process is a semimartingale can often be reduced to a path property, when a certain associated infinitely divisible...

Relational Reasoning about Numbers and Operations--Foundation for Calculation Strategy Use in Multi-Digit Multiplication and Division

Science.gov (United States)

Schulz, Andreas

2018-01-01

Theoretical analysis of whole number-based calculation strategies and digit-based algorithms for multi-digit multiplication and division reveals that strategy use includes two kinds of reasoning: reasoning about the relations between numbers and reasoning about the relations between operations. In contrast, algorithms aim to reduce the necessary…

Gigabit Access Passive Optical Network Using Wavelength Division Multiplexing—GigaWaM

DEFF Research Database (Denmark)

Iglesias Olmedo, Miguel; Suhr, Lau; Prince, Kamau

2014-01-01

passive optical network (WDM-PON) architecture that can deliver symmetric 1 Gb/s to 64 users over 20 km standard single mode fiber using the L and C bands for down and upstream, respectively. During the course of the project, a number of key enabling technologies were developed including tunable......This paper summarizes the research and technical achievements done under the EU project GigaWaM. The goal of this project was to develop a cost-effective solution that can meet the increasing bandwidth demands in access networks. The approach was to use a novel wavelength division multiplexing...... transceivers, athermal 50 GHz spaced arrayed waveguide grating multiplexer devices, novel hybridization technologies for integration of passive and active electro-optic devices, and system-level algorithms that ensure the quality of service. The outcome of the project proved a reliable, cost...

Multiple access chaotic digital communication based on generalized synchronization

International Nuclear Information System (INIS)

Lu Junguo

2005-01-01

A novel method for multiple access chaotic digital communication based on the concept of chaos generalized synchronization and the on-line least square method is proposed. This method can be used for transmitting multiple digital information signals concurrently. We illustrate the method using a Lorenz system driving a Chua's circuit and then examine the robustness of the proposed method with respect to noise in communication channel

Validation and analysis of the coupled multiple response Colorado upper-division electrostatics diagnostic

Directory of Open Access Journals (Sweden)

Bethany R. Wilcox

2015-11-01

Full Text Available Standardized conceptual assessment represents a widely used tool for educational researchers interested in student learning within the standard undergraduate physics curriculum. For example, these assessments are often used to measure student learning across educational contexts and instructional strategies. However, to support the large-scale implementation often required for cross-institutional testing, it is necessary for these instruments to have question formats that facilitate easy grading. Previously, we created a multiple-response version of an existing, validated, upper-division electrostatics diagnostic with the goal of increasing the instrument’s potential for large-scale implementation. Here, we report on the validity and reliability of this new version as an independent instrument. These findings establish the validity of the multiple-response version as measured by multiple test statistics including item difficulty, item discrimination, and internal consistency. Moreover, we demonstrate that the majority of student responses to the new version are internally consistent even when they are incorrect and provide an example of how the new format can be used to gain insight into student difficulties with specific content in electrostatics.

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

Science.gov (United States)

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

MULTIPLE ACCESS POINTS WITHIN THE ONLINE CLASSROOM: WHERE STUDENTS LOOK FOR INFORMATION

Directory of Open Access Journals (Sweden)

John STEELE

2017-01-01

Full Text Available The purpose of this study is to examine the impact of information placement within the confines of the online classroom architecture. Also reviewed was the impact of other variables such as course design, teaching presence and student patterns in looking for information. The sample population included students from a major online university in their first year course sequence. Students were tasked with completing a survey at the end of the course, indicating their preference for accessing information within the online classroom. The qualitative data indicated that student preference is to receive information from multiple access points and sources within the online classroom architecture. Students also expressed a desire to have information delivered through the usage of technology such as email and text messaging. In addition to receiving information from multiple sources, the qualitative data indicated students were satisfied overall, with the current ways in which they received and accessed information within the online classroom setting. Major findings suggest that instructors teaching within the online classroom should have multiple data access points within the classroom architecture. Furthermore, instructors should use a variety of communication venues to enhance the ability for students to access and receive information pertinent to the course.

Parallel optoelectronic trinary signed-digit division

Science.gov (United States)

Alam, Mohammad S.

1999-03-01

The trinary signed-digit (TSD) number system has been found to be very useful for parallel addition and subtraction of any arbitrary length operands in constant time. Using the TSD addition and multiplication modules as the basic building blocks, we develop an efficient algorithm for performing parallel TSD division in constant time. The proposed division technique uses one TSD subtraction and two TSD multiplication steps. An optoelectronic correlator based architecture is suggested for implementation of the proposed TSD division algorithm, which fully exploits the parallelism and high processing speed of optics. An efficient spatial encoding scheme is used to ensure better utilization of space bandwidth product of the spatial light modulators used in the optoelectronic implementation.

Partial Interference and Its Performance Impact on Wireless Multiple Access Networks

Directory of Open Access Journals (Sweden)

Lau WingCheong

2010-01-01

Full Text Available To determine the capacity of wireless multiple access networks, the interference among the wireless links must be accurately modeled. In this paper, we formalize the notion of the partial interference phenomenon observed in many recent wireless measurement studies and establish analytical models with tractable solutions for various types of wireless multiple access networks. In particular, we characterize the stability region of IEEE 802.11 networks under partial interference with two potentially unsaturated links numerically. We also provide a closed-form solution for the stability region of slotted ALOHA networks under partial interference with two potentially unsaturated links and obtain a partial characterization of the boundary of the stability region for the general M-link case. Finally, we derive a closed-form approximated solution for the stability region for general M-link slotted ALOHA system under partial interference effects. Based on our results, we demonstrate that it is important to model the partial interference effects while analyzing wireless multiple access networks. This is because such considerations can result in not only significant quantitative differences in the predicted system capacity but also fundamental qualitative changes in the shape of the stability region of the systems.

Optically transparent multiple access networks employing incoherent spectral codes

NARCIS (Netherlands)

Huiszoon, B.

2008-01-01

This Ph.D. thesis is divided into 7 chapters to provide the reader an overview of the main results achieved in di®erent sub-topics of the study towards optically transparent multiple access networks employing incoherent spectral codes taking into account wireless transmission aspects. The work

Power Efficient Division and Square Root Unit

DEFF Research Database (Denmark)

Liu, Wei; Nannarelli, Alberto

2012-01-01

Although division and square root are not frequent operations, most processors implement them in hardware to not compromise the overall performance. Two classes of algorithms implement division or square root: digit-recurrence and multiplicative (e.g., Newton-Raphson) algorithms. Previous work....... The proposed unit is compared to similar solutions based on the digit-recurrence algorithm and it is compared to a unit based on the multiplicative Newton-Raphson algorithm....

WCDMA Uplink Interference Assessment from Multiple High Altitude Platform Configurations

Directory of Open Access Journals (Sweden)

Grace D

2008-01-01

Full Text Available Abstract We investigate the possibility of multiple high altitude platform (HAP coverage of a common cell area using a wideband code division multiple access (WCDMA system. In particular, we study the uplink system performance of the system. The results show that depending on the traffic demand and the type of service used, there is a possibility of deploying 3–6 HAPs covering the same cell area. The results also show the effect of cell radius on performance and the position of the multiple HAP base stations which give the worst performance.

A Systematic Scheme for Multiple Access in Ethernet Passive Optical Access Networks

Science.gov (United States)

Ma, Maode; Zhu, Yongqing; Hiang Cheng, Tee

2005-11-01

While backbone networks have experienced substantial changes in the last decade, access networks have not changed much. Recently, passive optical networks (PONs) seem to be ready for commercial deployment as access networks, due to the maturity of a number of enabling technologies. Among the PON technologies, Ethernet PON (EPON) standardized by the IEEE 802.3ah Ethernet in the First Mile (EFM) Task Force is the most attractive one because of its high speed, low cost, familiarity, interoperability, and low overhead. In this paper, we consider the issue of upstream channel sharing in the EPONs. We propose a novel multiple-access control scheme to provide bandwidth-guaranteed service for high-demand customers, while providing best effort service to low-demand customers according to the service level agreement (SLA). The analytical and simulation results prove that the proposed scheme performs best in what it is designed to do compared to another well-known scheme that has not considered providing differentiated services. With business customers preferring premium services with guaranteed bandwidth and residential users preferring low-cost best effort services, our scheme could benefit both groups of subscribers, as well as the operators.

A multiple-choice knapsack based algorithm for CDMA downlink rate differentiation under uplink coverage restrictions

NARCIS (Netherlands)

Endrayanto, A.I.; Bumb, A.F.; Boucherie, Richardus J.

2004-01-01

This paper presents an analytical model for downlink rate allocation in Code Division Multiple Access (CDMA) mobile networks. By discretizing the coverage area into small segments, the transmit power requirements are characterized via a matrix representation that separates user and system

Multiple access protocol for supporting multimedia services in wireless ATM networks

DEFF Research Database (Denmark)

Liu, Hong; Dittmann, Lars; Gliese, Ulrik Bo

1999-01-01

The furture broadband wireless asynchronous transfer mode (ATM) networks must provide seamless extension of multimedia services from the wireline ATM networks. This requires an effecient wireless access protocol to fulfill varying Quality-og-Service (QoS) requirements for multimedia applications....... In this paper, we propose a multiple access protocol using centralized and distributed channel access control techniques to provide QoS guarantees for multimedia services by taking advantage of the characteristics of different kinds of ATM traffics. Multimedia traffic, including constant bit rate (CBR...

On Buffer-Aided Multiple-Access Relay Channel

DEFF Research Database (Denmark)

Liu, Rongkuan; Popovski, Petar; Wang, Gang

2016-01-01

This letter treats uplink scenario where M user equipments (UEs) send to a base station (BS), possibly via a common relay station (RS) that is equipped with a buffer. This is a multiple-access relay channel aided by a buffer. We devise a protocol in which the transmission mode is selected...... entirely at the BS, while simultaneously a number of UEs sends new messages to the BS. The results show that the adaptive selection of direct and buffer-aided relay transmissions leads to significant average throughput gains....

A comparison of Frequency Domain Multiple Access (FDMA) and Time Domain Multiple Access (TDMA) approaches to satellite service for low data rate Earth stations

Science.gov (United States)

Stevens, G.

1983-01-01

A technological and economic assessment is made of providing low data rate service to small earth stations by satellite at Ka-band. Various Frequency Domain Multiple Access (FDMA) and Time Domain Multiple Access (TDMA) scenarios are examined and compared on the basis of cost to the end user. Very small stations (1 to 2 meters in diameter) are found not to be viable alternatives to available terrestrial services. However, medium size (3 to 5 meters) earth stations appear to be very competitive if a minimum throughput of about 1.5 Mbs is maintained. This constrains the use of such terminals to large users and shared use by smaller users. No advantage was found to the use of FDMA. TDMA had a slight advantage from a total system viewpoint and a very significant advantage in the space segment (about 1/3 the required payload weight for an equivalent capacity).

Key issues of multiple access technique for LEO satellite communication systems

Institute of Scientific and Technical Information of China (English)

温萍萍; 顾学迈

2004-01-01

The large carrier frequency shift caused by the high-speed movement of satellite (Doppler effects) and the propagation delay on the up-down link are very critical issues in an LEO satellite communication system, which affects both the selection and the implementation of a suitable access method. A Doppler based multiple access technique is used here to control the flow and an MPRMA-HS protocol is proposed for the application in LEO satellite communication systems. The extended simulation trials prove that the proposed scheme seems to be a very promising access method.

Low-sampling-rate M-ary multiple access UWB communications in multipath channels

KAUST Repository

Alkhodary, Mohammad T.

2015-08-31

The desirable characteristics of ultra-wideband (UWB) technology are challenged by formidable sampling frequency, performance degradation in the presence of multi-user interference, and complexity of the receiver due to the channel estimation process. In this paper, a low-rate-sampling technique is used to implement M-ary multiple access UWB communications, in both the detection and channel estimation stages. A novel approach is used for multiple-access-interference (MAI) cancelation for the purpose of channel estimation. Results show reasonable performance of the proposed receiver for different number of users operating many times below Nyquist rate.

Low-sampling-rate M-ary multiple access UWB communications in multipath channels

KAUST Repository

Alkhodary, Mohammad T.; Ballal, Tarig; Al-Naffouri, Tareq Y.; Muqaibel, Ali H.

2015-01-01

The desirable characteristics of ultra-wideband (UWB) technology are challenged by formidable sampling frequency, performance degradation in the presence of multi-user interference, and complexity of the receiver due to the channel estimation process. In this paper, a low-rate-sampling technique is used to implement M-ary multiple access UWB communications, in both the detection and channel estimation stages. A novel approach is used for multiple-access-interference (MAI) cancelation for the purpose of channel estimation. Results show reasonable performance of the proposed receiver for different number of users operating many times below Nyquist rate.

Single and multiple object tracking using log-euclidean Riemannian subspace and block-division appearance model.

Science.gov (United States)

Hu, Weiming; Li, Xi; Luo, Wenhan; Zhang, Xiaoqin; Maybank, Stephen; Zhang, Zhongfei

2012-12-01

Object appearance modeling is crucial for tracking objects, especially in videos captured by nonstationary cameras and for reasoning about occlusions between multiple moving objects. Based on the log-euclidean Riemannian metric on symmetric positive definite matrices, we propose an incremental log-euclidean Riemannian subspace learning algorithm in which covariance matrices of image features are mapped into a vector space with the log-euclidean Riemannian metric. Based on the subspace learning algorithm, we develop a log-euclidean block-division appearance model which captures both the global and local spatial layout information about object appearances. Single object tracking and multi-object tracking with occlusion reasoning are then achieved by particle filtering-based Bayesian state inference. During tracking, incremental updating of the log-euclidean block-division appearance model captures changes in object appearance. For multi-object tracking, the appearance models of the objects can be updated even in the presence of occlusions. Experimental results demonstrate that the proposed tracking algorithm obtains more accurate results than six state-of-the-art tracking algorithms.

Metro-access integrated network based on optical OFDMA with dynamic sub-carrier allocation and power distribution.

Science.gov (United States)

Zhang, Chongfu; Zhang, Qiongli; Chen, Chen; Jiang, Ning; Liu, Deming; Qiu, Kun; Liu, Shuang; Wu, Baojian

2013-01-28

We propose and demonstrate a novel optical orthogonal frequency-division multiple access (OFDMA)-based metro-access integrated network with dynamic resource allocation. It consists of a single fiber OFDMA ring and many single fiber OFDMA trees, which transparently integrates metropolitan area networks with optical access networks. The single fiber OFDMA ring connects the core network and the central nodes (CNs), the CNs are on demand reconfigurable and use multiple orthogonal sub-carriers to realize parallel data transmission and dynamic resource allocation, meanwhile, they can also implement flexible power distribution. The remote nodes (RNs) distributed in the user side are connected by the single fiber OFDMA trees with the corresponding CN. The obtained results indicate that our proposed metro-access integrated network is feasible and the power distribution is agile.

The exp-normal distribution is infinitely divisible

OpenAIRE

Pinelis, Iosif

2018-01-01

Let $Z$ be a standard normal random variable (r.v.). It is shown that the distribution of the r.v. $\\ln|Z|$ is infinitely divisible; equivalently, the standard normal distribution considered as the distribution on the multiplicative group over $\\mathbb{R}\\setminus\\{0\\}$ is infinitely divisible.

WCDMA Uplink Interference Assessment from Multiple High Altitude Platform Configurations

Directory of Open Access Journals (Sweden)

A. Mohammed

2008-06-01

Full Text Available We investigate the possibility of multiple high altitude platform (HAP coverage of a common cell area using a wideband code division multiple access (WCDMA system. In particular, we study the uplink system performance of the system. The results show that depending on the traffic demand and the type of service used, there is a possibility of deploying 3–6 HAPs covering the same cell area. The results also show the effect of cell radius on performance and the position of the multiple HAP base stations which give the worst performance.

Digital Arithmetic: Division Algorithms

DEFF Research Database (Denmark)

Montuschi, Paolo; Nannarelli, Alberto

2017-01-01

Division is one of the basic arithmetic operations supported by every computer system. The operation can be performed and implemented by either hardware or software, or by a combination of the two. Although division is not as frequent as addition and multiplication, nowadays, most processors impl...... significant hardware resources and is more suitable for software implementation on the existing multiply units. The purpose of this entry is to provide an introductory survey using a presentation style suitable for the interested non-specialist readers as well....

Single-word multiple-bit upsets in static random access devices

International Nuclear Information System (INIS)

Koga, R.; Pinkerton, S.D.; Lie, T.J.; Crawford, K.B.

1993-01-01

Energetic ions and protons can cause single event upsets (SEUs) in static random access memory (SRAM) cells. In some cases multiple bits may be upset as the result of a single event. Space-borne electronics systems incorporating high-density SRAM are vulnerable to single-word multiple-bit upsets (SMUs). The authors review here recent observations of SMU, present the results of a systematic investigation of the physical cell arrangements employed in several currently available SRAM device types, and discuss implications for the occurrence and mitigation of SMU

Coupled multiple-response versus free-response conceptual assessment: An example from upper-division physics

Directory of Open Access Journals (Sweden)

Bethany R. Wilcox

2014-10-01

Full Text Available Free-response research-based assessments, like the Colorado Upper-division Electrostatics Diagnostic (CUE, provide rich, fine-grained information about students’ reasoning. However, because of the difficulties inherent in scoring these assessments, the majority of the large-scale conceptual assessments in physics are multiple choice. To increase the scalability and usability of the CUE, we set out to create a new version of the assessment that preserves the insights afforded by a free-response format while exploiting the logistical advantages of a multiple-choice assessment. We used our extensive database of responses to the free-response CUE to construct distractors for a new version where students can select multiple responses and receive partial credit based on the accuracy and consistency of their selections. Here, we describe the development of this modified CUE format, which we call coupled multiple response (CMR, and present data from direct comparisons of both versions. We find that the two formats have the same average score and perform similarly on multiple measures of validity and reliability, suggesting that the new version is a potentially viable alternative to the original CUE for the purpose of large-scale research-based assessment. We also compare the details of student responses on each of the two versions. While the CMR version does not capture the full scope of potential student responses, nearly three-quarters of our students’ responses to the free-response version contained one or more elements that matched options provided on the CMR version.

Performance Analysis of DPSK-OCDMA System for Optical Access Network

Science.gov (United States)

Islam, Monirul; Ahmed, N.; Aljunid, S. A.; Ali, Sharafat; Sayeed, S.; Sabri, Naseer

2016-03-01

In this research, the performance of optical code division multiple access (OCDMA) using differential phase shift keying (DPSK) has been compared with OCDMA On-Off Keying (OOK). This comparison took place in terms of bit error rate (BER) and receiver power where two bit rates (155 Mbps and 622 Mbps) have been used for this analysis. Using of OptiSystem 7.0 simulation, comparing eye diagram and optical spectrum alongside with BER and Rx power. It is found that OCDMA-DPSK performs better in comparison to OCDMA-OOK. The performance analysis also provides parameter for designing and development of an OCDMA system for optical access network using DPSK.

Electromagnetic interference-aware transmission scheduling and power control for dynamic wireless access in hospital environments.

Science.gov (United States)

Phunchongharn, Phond; Hossain, Ekram; Camorlinga, Sergio

2011-11-01

We study the multiple access problem for e-Health applications (referred to as secondary users) coexisting with medical devices (referred to as primary or protected users) in a hospital environment. In particular, we focus on transmission scheduling and power control of secondary users in multiple spatial reuse time-division multiple access (STDMA) networks. The objective is to maximize the spectrum utilization of secondary users and minimize their power consumption subject to the electromagnetic interference (EMI) constraints for active and passive medical devices and minimum throughput guarantee for secondary users. The multiple access problem is formulated as a dual objective optimization problem which is shown to be NP-complete. We propose a joint scheduling and power control algorithm based on a greedy approach to solve the problem with much lower computational complexity. To this end, an enhanced greedy algorithm is proposed to improve the performance of the greedy algorithm by finding the optimal sequence of secondary users for scheduling. Using extensive simulations, the tradeoff in performance in terms of spectrum utilization, energy consumption, and computational complexity is evaluated for both the algorithms.

Non-Orthogonal Multiple Access for Ubiquitous Wireless Sensor Networks.

Science.gov (United States)

Anwar, Asim; Seet, Boon-Chong; Ding, Zhiguo

2018-02-08

Ubiquitous wireless sensor networks (UWSNs) have become a critical technology for enabling smart cities and other ubiquitous monitoring applications. Their deployment, however, can be seriously hampered by the spectrum available to the sheer number of sensors for communication. To support the communication needs of UWSNs without requiring more spectrum resources, the power-domain non-orthogonal multiple access (NOMA) technique originally proposed for 5th Generation (5G) cellular networks is investigated for UWSNs for the first time in this paper. However, unlike 5G networks that operate in the licensed spectrum, UWSNs mostly operate in unlicensed spectrum where sensors also experience cross-technology interferences from other devices sharing the same spectrum. In this paper, we model the interferences from various sources at the sensors using stochastic geometry framework. To evaluate the performance, we derive a theorem and present new closed form expression for the outage probability of the sensors in a downlink scenario under interference limited environment. In addition, diversity analysis for the ordered NOMA users is performed. Based on the derived outage probability, we evaluate the average link throughput and energy consumption efficiency of NOMA against conventional orthogonal multiple access (OMA) technique in UWSNs. Further, the required computational complexity for the NOMA users is presented.

Knowledge-Based Multiple Access Protocol in Broadband Wireless ATM Networks

DEFF Research Database (Denmark)

Liu, Hong; Gliese, Ulrik Bo; Dittmann, Lars

1999-01-01

In this paper, we propose a knowledge-based multiple access protocol for the extension of wireline ATM to wireless networks. The objective is to enable effecient transmission of all kinds of ATM traffic in the wireless channel with guaranteed QoS.The proposed protocol utilixes knowledge of the main...... guaranteed QoS requirements to a variety of ATM applications....

A Multiple-Reception Access Protocol with Interruptions with Mixed Priorities in CDMA Networks

Institute of Scientific and Technical Information of China (English)

Lu Xiaowen; Zhu Jinkang

2003-01-01

A novel access protocol called Multiple-Reception Access Protocol (MRAP) and its modification MRAP/WI are proposed. In this protocol, all colliding users with a common code can be identified by the base station due to the offset of arrival time Thus they can retransmit access requests under the base station's control. Furthermore new arrivals with higher priority level can interrupt the lower retransmission in order to reduce its access delay although it increases the lower priority's delay. Simulation results of MRAP and MRAP/WI are given in order to highlight the superior performance of the proposed approach.

Experimental Facilities Division/User Program Division technical progress report 1999-2000

International Nuclear Information System (INIS)

2001-01-01

In October 1999, the two divisions of the Advanced Photon Source (APS), the Accelerator Systems Division (ASD) and the Experimental Facilities Division (XFD), were reorganized into four divisions (see high-level APS organizational chart, Fig. 1.1). In addition to ASD and XFD, two new divisions were created, the APS Operations Division (AOD), to oversee APS operations, and the User Program Division (UPD), to serve the APS user community by developing and maintaining the highest quality user technical and administration support. Previous XFD Progress Reports (ANL/APS/TB-30 and ANL/APS/TB-34) covered a much broader base, including APS user administrative support and what was previously XFD operations (front ends, interlocks, etc.) This Progress Report summarizes the main scientific and technical activities of XFD, and the technical support, research and development (R and D) activities of UPD from October 1998 through November 2000. The report is divided into four major sections, (1) Introduction, (2) SRI-CAT Beamlines, Technical Developments, and Scientific Applications, (3) User Technical Support, and (4) Major Plans for the Future. Sections 2 and 3 describe the technical activities and research accomplishments of the XFD and UPD personnel in supporting the synchrotron radiation instrumentation (SRI) collaborative access team (CAT) and the general APS user community. Also included in this report is a comprehensive list of publications (Appendix 1) and presentations (Appendix 2) by XFD and UPD staff during the time period covered by this report. The organization of section 2, SRI CAT Beamlines, Technical Developments, and Scientific Applications has been made along scientific techniques/disciplines and not ''geographical'' boundaries of the sectors in which the work was performed. Therefore items under the subsection X-ray Imaging and Microfocusing could have been (and were) performed on several different beamlines by staff in different divisions. The management of

Access to DIII-D data located in multiple files and multiple locations

International Nuclear Information System (INIS)

McHarg, B.B. Jr.

1993-10-01

The General Atomics DIII-D tokamak fusion experiment is now collecting over 80 MB of data per discharge once every 10 min, and that quantity is expected to double within the next year. The size of the data files, even in compressed format, is becoming increasingly difficult to handle. Data is also being acquired now on a variety of UNIX systems as well as MicroVAX and MODCOMP computer systems. The existing computers collect all the data into a single shot file, and this data collection is taking an ever increasing amount of time as the total quantity of data increases. Data is not available to experimenters until it has been collected into the shot file, which is in conflict with the substantial need for data examination on a timely basis between shots. The experimenters are also spread over many different types of computer systems (possibly located at other sites). To improve data availability and handling, software has been developed to allow individual computer systems to create their own shot files locally. The data interface routine PTDATA that is used to access DIII-D data has been modified so that a user's code on any computer can access data from any computer where that data might be located. This data access is transparent to the user. Breaking up the shot file into separate files in multiple locations also impacts software used for data archiving, data management, and data restoration

A USER－DEPENDENT PERFECT－SCHEDULING MULTIPLE ACCESS PROTOCOL FOR VOICE－DATA INTEGRATION IN WIRELESS NETWORKDS

Institute of Scientific and Technical Information of China (English)

无

2002-01-01

A novel Multiple Access Control(MAC) protocol-User-dependent Perfect-scheduling Multiple Access(UPMA) protocol,which supports joint transmission of voice and data packets,is proposed.By this protocol,the bandwidth can be allocated dynamically to the uplink and downlink traffic with on-demand assignment and the transmission of Mobile Terminals(MTs) can be perfectly scheduled by means of polling.Meanwhile.a unique frame stucture is designed to guarantee Quality of Service(QoS) in voice traffic supporting.An effective colision resolution algorthm is also proposed to guarantee rapid channel access for activated MTs.Finally,performance of UPMA protocol is evaluated by simulation and compared with MPRMA protocol.Simulation results show that UPMA protocol has better performance.

A USER-DEPENDENT PERFECT-SCHEDULING MULTIPLE ACCESS PROTOCOL FOR VOICE-DATA INTEGRATION IN WIRELESS NETWORKS

Institute of Scientific and Technical Information of China (English)

Zhou Yajian; Li Jiandong; Liu Kai

2002-01-01

A novel Multiple Access Control (MAC) protocol - User-dependent Perfect-scheduling Multiple Access (UPMA) protocol, which supports joint transmission of voice and data packets,is proposed. By this protocol, the bandwidth can be allocated dynamically to the uplink and downlink traffic with on-demand assignment and the transmission of Mobile Terminals (MTs)can be perfectly scheduled by means of polling. Meanwhile, a unique frame structure is designed to guarantee Quality of Service (QoS) in voice traffic supporting. An effective collision resolution algorithm is also proposed to guarantee rapid channel access for activated MTs. Finally, performance of UPMA protocol is evaluated by simulation and compared with MPRMA protocol.Simulation results show that UPMA protocol has better performance.

Downlink Non-Orthogonal Multiple Access (NOMA) in Poisson Networks

KAUST Repository

Ali, Konpal S.

2018-03-21

A network model is considered where Poisson distributed base stations transmit to $N$ power-domain non-orthogonal multiple access (NOMA) users (UEs) each that employ successive interference cancellation (SIC) for decoding. We propose three models for the clustering of NOMA UEs and consider two different ordering techniques for the NOMA UEs: mean signal power-based and instantaneous signal-to-intercell-interference-and-noise-ratio-based. For each technique, we present a signal-to-interference-and-noise ratio analysis for the coverage of the typical UE. We plot the rate region for the two-user case and show that neither ordering technique is consistently superior to the other. We propose two efficient algorithms for finding a feasible resource allocation that maximize the cell sum rate $\\\\mathcal{R}_{\\ m tot}$, for general $N$, constrained to: 1) a minimum rate $\\\\mathcal{T}$ for each UE, 2) identical rates for all UEs. We show the existence of: 1) an optimum $N$ that maximizes the constrained $\\\\mathcal{R}_{\\ m tot}$ given a set of network parameters, 2) a critical SIC level necessary for NOMA to outperform orthogonal multiple access. The results highlight the importance in choosing the network parameters $N$, the constraints, and the ordering technique to balance the $\\\\mathcal{R}_{\\ m tot}$ and fairness requirements. We also show that interference-aware UE clustering can significantly improve performance.

Downlink Non-Orthogonal Multiple Access (NOMA) in Poisson Networks

KAUST Repository

Ali, Konpal S.; Haenggi, Martin; Elsawy, Hesham; Chaaban, Anas; Alouini, Mohamed-Slim

2018-01-01

A network model is considered where Poisson distributed base stations transmit to $N$ power-domain non-orthogonal multiple access (NOMA) users (UEs) each that employ successive interference cancellation (SIC) for decoding. We propose three models for the clustering of NOMA UEs and consider two different ordering techniques for the NOMA UEs: mean signal power-based and instantaneous signal-to-intercell-interference-and-noise-ratio-based. For each technique, we present a signal-to-interference-and-noise ratio analysis for the coverage of the typical UE. We plot the rate region for the two-user case and show that neither ordering technique is consistently superior to the other. We propose two efficient algorithms for finding a feasible resource allocation that maximize the cell sum rate $\\mathcal{R}_{\\rm tot}$, for general $N$, constrained to: 1) a minimum rate $\\mathcal{T}$ for each UE, 2) identical rates for all UEs. We show the existence of: 1) an optimum $N$ that maximizes the constrained $\\mathcal{R}_{\\rm tot}$ given a set of network parameters, 2) a critical SIC level necessary for NOMA to outperform orthogonal multiple access. The results highlight the importance in choosing the network parameters $N$, the constraints, and the ordering technique to balance the $\\mathcal{R}_{\\rm tot}$ and fairness requirements. We also show that interference-aware UE clustering can significantly improve performance.

IQ imbalance tolerable parallel-channel DMT transmission for coherent optical OFDMA access network

Science.gov (United States)

Jung, Sang-Min; Mun, Kyoung-Hak; Jung, Sun-Young; Han, Sang-Kook

2016-12-01

Phase diversity of coherent optical communication provides spectrally efficient higher-order modulation for optical communications. However, in-phase/quadrature (IQ) imbalance in coherent optical communication degrades transmission performance by introducing unwanted signal distortions. In a coherent optical orthogonal frequency division multiple access (OFDMA) passive optical network (PON), IQ imbalance-induced signal distortions degrade transmission performance by interferences of mirror subcarriers, inter-symbol interference (ISI), and inter-channel interference (ICI). We propose parallel-channel discrete multitone (DMT) transmission to mitigate transceiver IQ imbalance-induced signal distortions in coherent orthogonal frequency division multiplexing (OFDM) transmissions. We experimentally demonstrate the effectiveness of parallel-channel DMT transmission compared with that of OFDM transmission in the presence of IQ imbalance.

Student ownership of projects in an upper-division optics laboratory course: A multiple case study of successful experiences

Science.gov (United States)

Dounas-Frazer, Dimitri R.; Stanley, Jacob T.; Lewandowski, H. J.

2017-12-01

We investigate students' sense of ownership of multiweek final projects in an upper-division optics lab course. Using a multiple case study approach, we describe three student projects in detail. Within-case analyses focused on identifying key issues in each project, and constructing chronological descriptions of those events. Cross-case analysis focused on identifying emergent themes with respect to five dimensions of project ownership: student agency, instructor mentorship, peer collaboration, interest and value, and affective responses. Our within- and cross-case analyses yielded three major findings. First, coupling division of labor with collective brainstorming can help balance student agency, instructor mentorship, and peer collaboration. Second, students' interest in the project and perceptions of its value can increase over time; initial student interest in the project topic is not a necessary condition for student ownership of the project. Third, student ownership is characterized by a wide range of emotions that fluctuate as students alternate between extended periods of struggle and moments of success while working on their projects. These findings not only extend the literature on student ownership into a new educational domain—namely, upper-division physics labs—they also have concrete implications for the design of experimental physics projects in courses for which student ownership is a desired learning outcome. We describe the course and projects in sufficient detail that others can adapt our results to their particular contexts.

Transformation of fractions into simple fractions in divisive meadows

NARCIS (Netherlands)

Bergstra, J.A.; Middelburg, C.A.

Meadows are alternatives for fields with a purely equational axiomatization. At the basis of meadows lies the decision to make the multiplicative inverse operation total by imposing that the multiplicative inverse of zero is zero. Divisive meadows are meadows with the multiplicative inverse

Is Z Division of the Achilles Tendon always Necessary in Wide ...

African Journals Online (AJOL)

Method: From 15/12/1997 to 30/12/2006 sixteen patients required surgical management of distal tibia fractures involving articular surfaces. Posterior approach with. Achilles tendon division was indicated for satisfactory access to the back of tibia and ankle. In equal number of these patients division of the Achilles tendon ...

Implementation of Multiple Access Techniques Applicable for Maritime Satellite Communications

OpenAIRE

Stojce Dimov Ilcev

2013-01-01

In this paper are introduced fundamentals, characteristics, advantages and disadvantages of Multiple Access (MA) employed as transmission techniques in the Maritime Mobile Satellite Communications (MMSC) between ships and Coast Earth Station (CES) via Geostationary Earth Orbit (GEO) or Not-GEO satellite constellations. In fixed satellite communication, as a rule, especially in MMSC many users are active at the same time. The problem of simultaneous communications between many single or multip...

Student ownership of projects in an upper-division optics laboratory course: A multiple case study of successful experiences

Directory of Open Access Journals (Sweden)

Dimitri R. Dounas-Frazer

2017-12-01

Full Text Available We investigate students’ sense of ownership of multiweek final projects in an upper-division optics lab course. Using a multiple case study approach, we describe three student projects in detail. Within-case analyses focused on identifying key issues in each project, and constructing chronological descriptions of those events. Cross-case analysis focused on identifying emergent themes with respect to five dimensions of project ownership: student agency, instructor mentorship, peer collaboration, interest and value, and affective responses. Our within- and cross-case analyses yielded three major findings. First, coupling division of labor with collective brainstorming can help balance student agency, instructor mentorship, and peer collaboration. Second, students’ interest in the project and perceptions of its value can increase over time; initial student interest in the project topic is not a necessary condition for student ownership of the project. Third, student ownership is characterized by a wide range of emotions that fluctuate as students alternate between extended periods of struggle and moments of success while working on their projects. These findings not only extend the literature on student ownership into a new educational domain—namely, upper-division physics labs—they also have concrete implications for the design of experimental physics projects in courses for which student ownership is a desired learning outcome. We describe the course and projects in sufficient detail that others can adapt our results to their particular contexts.

Threshold-Based Multiple Optical Signal Selection Scheme for Free-Space Optical Wavelength Division Multiplexing Systems

KAUST Repository

Nam, Sung Sik

2017-11-13

We propose a threshold-based multiple optical signal selection scheme (TMOS) for free-space optical wavelength division multiplexing systems. With this scheme, we can obtain higher spectral efficiency while reducing the possible complexity of implementation caused by the beam-selection scheme and without a considerable performance loss. To characterize the performance of our scheme, we statistically analyze the operation characteristics under conventional detection conditions (i.e., heterodyne detection and intensity modulation/direct detection techniques) with log-normal turbulence while taking into consideration the impact of pointing error. More specifically, we derive exact closed-form expressions for the outage probability, the average bit error rate, and the average spectral efficiency while adopting an adaptive modulation. Some selected results show that TMOS increases the average spectral efficiency while maintaining a minimum average bit error rate requirement.

Optical CDMA and WDMA in the access network

Science.gov (United States)

Sargent, Edward H.; Stok, Andrew

2003-08-01

Optical CDMA provides one avenue to sharing the vast bandwidth of optical fiber among a number of active users in a network. In this work we address two questions central to considering the areas of applicability of CDMA in optics: (1) How do we compare fairly optical CDMA codes of different families, and what do we conclude? (2) How do we compare optical CDMA performance with that of conventional optical WDMA? To answer the first question, we present a method of comparing optical CDMA codes of different families, sizes and weights. We outline why the traditional performance metric of bit-error rate versus number of simultaneous users is lacking and propose a different performance measure -- the peak throughput normalized with respect to the size of the code. This metric is used to show that optical-orthogonal codes (OOCs) with a weight of 4 perform best at low offered loads while OOCs with weight 5 should be used at higher offered loads. By applying the technique across different families of codes, we demonstrate that multi-wavelength OOCs (MWOOCs) perform better than both OOCs (by a factor of approximately 1.25) and asymmetric prime-hop codes (by a factor of approximately 3.5), over a wide range of offered loads. In answer to the second question, we present a comparison of the performance of optical code-division multiple-access (CDMA) systems with that of a wavelength-division multiple-access (WDMA) system. The multiple-access techniques are applied in a time-slotted broadcast local-area network. The utilization, defined as the throughput per unit of time-domain bandwidth expansion, and packet delay are used as metrics of performance. When more than seven wavelengths are available, optical CDMA systems using asymmetric prime-hop codes and all-optical signal processing are shown to have higher peak utilization and lower corresponding delay than a WDMA system with the same number of wavelengths. When the encoders/decoders operate at the chip rate, the utilization

The Effects of Noncontingent Access to Single-versus Multiple-Stimulus Sets on Self-Injurious Behavior.

Science.gov (United States)

DeLeon, Iser G.; Anders, Bonita M.; Rodriguez-Catter, Vanessa; Neidert, Pamela L.

2000-01-01

The automatically reinforced self-injury of a girl (age 11) with autism was treated by providing noncontingent access to a single set of preferred toys during 30-minute sessions. Rotating toy sets after 10 minutes or providing access to multiple toy sets resulted in reductions that lasted the entire 30 minutes. (Contains four references.)…

Performance analysis of quantum access network using code division multiple access model

Science.gov (United States)

Hu, Linxi; Yang, Can; He, Guangqiang

2017-06-01

Not Available Project supported by the National Natural Science Foundation of China (Grant Nos. 61475099 and 61102053), the Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices (Grant No. KF201405), the Open Fund of IPOC (BUPT) (Grant No. IPOC2015B004), and the Program of State Key Laboratory of Information Security (Grant No. 2016-MS-05).

Performance of Non-Orthogonal Multiple Access (NOMA) in mmWave wireless communications for 5G networks

DEFF Research Database (Denmark)

Marcano, Andrea; Christiansen, Henrik Lehrmann

2017-01-01

Among the key technologies that have been identified as capacity boosters for fifth generation - 5G - mobile networks, are millimeter wave (mmWave) transmissions and non-orthogonal multiple access (NOMA). The large amount of spectrum available at mmWave frequencies combined with a more effective...... use of available resources, helps improving the overall capacity. NOMA, unlike orthogonal multiple access (OMA) methods, allows sharing the same frequency resources at the same time, by implementing adaptive power allocation. In this paper we present a performance analysis of NOMA in mmWave cells...

Power Allocation in Multiple Access Networks: Implementation Aspects via Verhulst and Perron-Frobenius Models

Directory of Open Access Journals (Sweden)

Fábio Engel de Camargo

2012-11-01

Full Text Available In this work, the Verhulst model and the Perron-Frobenius theorem are applied on the power control problem which is a concern in multiple access communication networks due to the multiple access interference. This paper deals with the performance versus complexity tradeoff of both power control algorithm (PCA, as well as highlights the computational cost aspects regarding the implementability of distributed PCA (DPCA version for both algorithms. As a proof-of-concept the DPCA implementation is carried out deploying a commercial point-floating DSP platform. Numerical results in terms of DSP cycles and computational time as well indicate a feasibility of implementing the PCA-Verhulst model in 2G and 3G cellular systems; b high computational cost for the PCA-Perron-Frobenius model.

Flexible Transmission Scheme for 4G Wireless Systems with Multiple Antennas

Directory of Open Access Journals (Sweden)

Horlin François

2005-01-01

Full Text Available New air interfaces are currently being developed to meet the high requirements of the emerging wireless communication systems. In this context, the combinations of the multicarrier (MC and spread-spectrum (SS technologies are promising candidates. In this paper, we propose a generic transmission scheme that allows to instantiate all the combinations of orthogonal frequency-division multiplexing (OFDM and cyclic-prefixed single-carrier (SC modulations with direct-sequence code-division multiple access (DS-CDMA. The generic transmission scheme is extended to integrate the space-division multiplexing (SDM and the orthogonal space-time block coding (STBC. Based on a generalized matrix model, the linear frequency-domain minimum mean square error (MMSE joint detector is derived. A mode selection strategy for up- and downlink is advised that efficiently trades off the cost of the mobile terminal and the achieved performance of a high-mobility cellular system. It is demonstrated that an adaptive transceiver that supports the proposed communication modes is necessary to track the changing communication conditions.

Reglas igualitarias para los problemas de reparto con referencias múltiples // Egalitarian Rules for Division Problems with Multiple References

Directory of Open Access Journals (Sweden)

Francisca J. Sánchez

2016-12-01

Full Text Available En los problemas de reparto que consideramos, hay que repartir un recurso con arreglo a unas referencias de los agentes. Analizaremos estos problemas en un contexto multidimensional pues consideraremos que los agentes tienen referencias múltiples. Para obtener repartos de la cantidad disponible en estas situaciones, es necesario diseñar reglas que tengan en cuenta la multidimensionalidad de las referencias de cada agente. Proponemos y analizamos distintas reglas de reparto que se basarán en un principio igualitario y proporcionamos un procedimiento para la selección de una única asignación. ------------------------------------ We consider the division problems in which a resource must be distributed considering agents' references. We analize this problems in a multidimensional context, we consider that agents have multiple references. For division of the amount available in these situations, we design rules that take into account the multidimensionality of the references of each agent. We propose and we analyze different rules based on an egalitarian principle and provide a procedure for the selection of a single allocation.

Multiple-division of self-propelled oil droplets through acetal formation.

Science.gov (United States)

Banno, Taisuke; Kuroha, Rie; Miura, Shingo; Toyota, Taro

2015-02-28

We demonstrate a novel system that exhibits both self-propelled motion and division of micrometer-sized oil droplets induced by chemical conversion of the system components. Such unique dynamics were observed in an oil-in-water emulsion of a benzaldehyde derivative, an alkanol and a cationic surfactant at a low pH.

Code-division multiple-access protocol for active RFID systems

Science.gov (United States)

Mazurek, Gustaw; Szabatin, Jerzy

2008-01-01

Most of the Radio Frequency Identification (RFID) systems operating in HF and UHF bands employ narrowband modulations (FSK or ASK) with Manchester coding. However, these simple transmission schemes are vulnerable to narrowband interference (NBI) generated by other radio systems working in the same frequency band, and also suffer from collision problem and need special anti-collision procedures. This becomes especially important when operating in a noisy, crowded industrial environment. In this paper we show the performance of RFID system with DS-CDMA transmission in comparison to a standard system with FSK modulation defined in ISO 18000-7. Our simulation results show that without any bandwidth expansion the immunity against NBI can be improved by 8 dB and the system capacity can be 7 times higher when using DS-CDMA transmission instead of FSK modulation with Manchester coding.

Simulation Performance of Multiple-Input Multiple-Output Systems Employing Single-Carrier Modulation and Orthogonal Frequency Division Multiplexing

National Research Council Canada - National Science Library

Saglam, Halil D

2004-01-01

...) systems utilizing Alamouti-based space-time block coding (STBC) technique. The MIMO communication systems using STBC technique employing both single-carrier modulation and orthogonal frequency division multiplexing (OFDM...

Mentorship programs for faculty development in academic general pediatric divisions.

Science.gov (United States)

Takagishi, Jennifer; Dabrow, Sharon

2011-01-01

Introduction. Mentoring relationships have been shown to support academicians in areas of research, work/life balance, and promotion. Methods. General pediatric division chiefs accessed an electronic survey asking about mentorship relationships, their ability to create a mentorship program, and resources needed. Results. Dyadic mentorship programs were available at 53% of divisions. Peer mentorship programs were available at 27% of divisions. Overall, 84% of chiefs believed that dyadic mentorship would benefit their faculty. 91% of chiefs believed that peer mentorship would benefit their faculty. Chiefs were interested in starting peer (57%) or dyadic (55%) mentorship programs. Few divisions had a peer mentorship program available, whereas 24% already had a dyadic program. 43% of chiefs felt that they had the tools to start a program. Many tools are needed to create a program. Discussion. General pediatric division chiefs acknowledge the benefits of mentoring relationships, and some have programs in place. Many need tools to create them. Pediatric societies could facilitate this critical area of professional development.

Theoretical analysis and simulation of a code division multiple access system (cdma for secure signal transmission in wideband channels

Directory of Open Access Journals (Sweden)

Stevan M. Berber

2014-06-01

Code Division Multiple Access (CDMA technique which allows communications of multiple users in the same communication system. This is achieved in such a way that each user is assigned a unique code sequence, which is used at the receiver side to discover the information dedicated to that user. These systems belong to the group of communication systems for direct sequence spread spectrum systems. Traditionally, CDMA systems use binary orthogonal spreading codes. In this paper, a mathematical model and simulation of a CDMA system based on the application of non-binary, precisely speaking, chaotic spreading sequences. In their nature, these sequences belong to random sequences with infinite periodicity, and due to that they are appropriate for applications in the systems that provide enhanced security against interception and secrecy in signal transmission. Numerous papers are dedicated to the development of CDMA systems in flat fading channels. This paper presents the results of these systems analysis for the case when frequency selective fading is present in the channel. In addition, the paper investigates a possibility of using interleaving techniques to mitigate fading in a wideband channel with the frequency selective fading. Basic structure of a CDMA communication system and its operation In this paper, a CDMA system block schematic is ppresented and the function of all blocks is explained. Notation  to be used in the paper is introduced. Chaotic sequences are defined and explained in accordance with the method of their generation. A wideband channel with frequency selective fading is defined by its impulse response function. Theoretical analysis of a CDMA system with flat fading in a narrowband channel A narrowband channel and flat fading are defined. A mathematical analysis of the system is conducted by presenting the signal expressions at vital points in the transmitter and receiver. The expression of the signal at the output of the sequence correlator is

An optimal probabilistic multiple-access scheme for cognitive radios

KAUST Repository

Hamza, Doha R.; Aï ssa, Sonia

2012-01-01

We study a time-slotted multiple-access system with a primary user (PU) and a secondary user (SU) sharing the same channel resource. The SU senses the channel at the beginning of the slot. If found free, it transmits with probability 1. If busy, it transmits with a certain access probability that is a function of its queue length and whether it has a new packet arrival. Both users, i.e., the PU and the SU, transmit with a fixed transmission rate by employing a truncated channel inversion power control scheme. We consider the case of erroneous sensing. The goal of the SU is to optimize its transmission scheduling policy to minimize its queueing delay under constraints on its average transmit power and the maximum tolerable primary outage probability caused by the miss detection of the PU. We consider two schemes regarding the secondary's reaction to transmission errors. Under the so-called delay-sensitive (DS) scheme, the packet received in error is removed from the queue to minimize delay, whereas under the delay-tolerant (DT) scheme, the said packet is kept in the buffer and is retransmitted until correct reception. Using the latter scheme, there is a probability of buffer loss that is also constrained to be lower than a certain specified value. We also consider the case when the PU maintains an infinite buffer to store its packets. In the latter case, we modify the SU access scheme to guarantee the stability of the PU queue. We show that the performance significantly changes if the realistic situation of a primary queue is considered. In all cases, although the delay minimization problem is nonconvex, we show that the access policies can be efficiently obtained using linear programming and grid search over one or two parameters. © 1967-2012 IEEE.

An optimal probabilistic multiple-access scheme for cognitive radios

KAUST Repository

Hamza, Doha R.

2012-09-01

We study a time-slotted multiple-access system with a primary user (PU) and a secondary user (SU) sharing the same channel resource. The SU senses the channel at the beginning of the slot. If found free, it transmits with probability 1. If busy, it transmits with a certain access probability that is a function of its queue length and whether it has a new packet arrival. Both users, i.e., the PU and the SU, transmit with a fixed transmission rate by employing a truncated channel inversion power control scheme. We consider the case of erroneous sensing. The goal of the SU is to optimize its transmission scheduling policy to minimize its queueing delay under constraints on its average transmit power and the maximum tolerable primary outage probability caused by the miss detection of the PU. We consider two schemes regarding the secondary\\'s reaction to transmission errors. Under the so-called delay-sensitive (DS) scheme, the packet received in error is removed from the queue to minimize delay, whereas under the delay-tolerant (DT) scheme, the said packet is kept in the buffer and is retransmitted until correct reception. Using the latter scheme, there is a probability of buffer loss that is also constrained to be lower than a certain specified value. We also consider the case when the PU maintains an infinite buffer to store its packets. In the latter case, we modify the SU access scheme to guarantee the stability of the PU queue. We show that the performance significantly changes if the realistic situation of a primary queue is considered. In all cases, although the delay minimization problem is nonconvex, we show that the access policies can be efficiently obtained using linear programming and grid search over one or two parameters. © 1967-2012 IEEE.

Fiber to the Home Using a PON Infrastructure

Science.gov (United States)

Lee, Chang-Hee; Sorin, Wayne V.; Kim, Byoung Yoon

2006-12-01

Traffic patterns in access networks have evolved from voice- and text-oriented services to video- and image-based services. This change will require new access networks that support high-speed (> 100 Mb/s), symmetric, and guaranteed bandwidths for future video services with high-definition TV quality. To satisfy the required bandwidth over a 20-km transmission distance, single-mode optical fiber is currently the only practical choice. To minimize the cost of implementing an FTTP solution, a passive optical network (PON) that uses a point-to-multipoint architecture is generally considered to be the best approach. There are several multiple-access techniques to share a single PON architecture, and the authors addressed several of these approaches such as time-division multiple access, wavelength-division multiple access, subcarrier multiple access, and code-division multiple access. Among these multiple techniques, they focus on time-division multiplexing (TDM)-PON and wavelength-division multiplexing (WDM)-PON, which will be the most promising candidates for practical future systems. A TDM-PON shares a single-transmission channel with multiple subscribers in time domain. Then, there exists tight coupling between subscribers. A WDM-PON provides point-to-point optical connectivity using a dedicated pair of wavelengths per user. While a TDM-PON appears to be a satisfactory solution for current bandwidth demands, the combination of future data-rate projections and traffic patterns coupled with recent advances in WDM technology may result in WDM-PON becoming the preferred solution for a future proof fiber-based access network.

32 X 2.5 Gb/s Optical Code Division Multiplexing (O-CDM) For Agile Optical Networking (Phase II) Final Report CRADA No. TC02051.0

Energy Technology Data Exchange (ETDEWEB)

Bennett, C. V. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mendez, A. J. [Mendez R & D Associates, El Segundo, CA (United States)

2017-09-08

This was a collaborative effort between Lawrence Livermore National Security, LLC (formerly The Regents of the University of California)/Lawrence Livermore National Laboratory (LLNL) and Mendez R & D Associates (MRDA) to develop and demonstrate a reconfigurable and cost effective design for optical code division multiplexing (O-CDM) with high spectral efficiency and throughput, as applied to the field of distributed computing, including multiple accessing (sharing of communication resources) and bidirectional data distribution in fiber-to-the-premise (FTTx) networks.

Lexical access changes in patients with multiple sclerosis: a two-year follow-up study.

Science.gov (United States)

Sepulcre, Jorge; Peraita, Herminia; Goni, Joaquin; Arrondo, Gonzalo; Martincorena, Inigo; Duque, Beatriz; Velez de Mendizabal, Nieves; Masdeu, Joseph C; Villoslada, Pablo

2011-02-01

The aim of the study was to analyze lexical access strategies in patients with multiple sclerosis (MS) and their changes over time. We studied lexical access strategies during semantic and phonemic verbal fluency tests and also confrontation naming in a 2-year prospective cohort of 45 MS patients and 20 healthy controls. At baseline, switching lexical access strategy (both in semantic and in phonemic verbal fluency tests) and confrontation naming were significantly impaired in MS patients compared with controls. After 2 years follow-up, switching score decreased, and cluster size increased over time in semantic verbal fluency tasks, suggesting a failure in the retrieval of lexical information rather than an impairment of the lexical pool. In conclusion, these findings underline the significant presence of lexical access problems in patients with MS and could point out their key role in the alterations of high-level communications abilities in MS.

An access technology delivery protocol for children with severe and multiple disabilities: a case demonstration.

Science.gov (United States)

Mumford, Leslie; Lam, Rachel; Wright, Virginia; Chau, Tom

2014-08-01

This study applied response efficiency theory to create the Access Technology Delivery Protocol (ATDP), a child and family-centred collaborative approach to the implementation of access technologies. We conducted a descriptive, mixed methods case study to demonstrate the ATDP method with a 12-year-old boy with no reliable means of access to an external device. Evaluations of response efficiency, satisfaction, goal attainment, technology use and participation were made after 8 and 16 weeks of training with a custom smile-based access technology. At the 16 week mark, the new access technology offered better response quality; teacher satisfaction was high; average technology usage was 3-4 times per week for up to 1 h each time; switch sensitivity and specificity reached 78% and 64%, respectively, and participation scores increased by 38%. This case supports further development and testing of the ATDP with additional children with multiple or severe disabilities.

Low Access Delay Anti-Collision Algorithm for Reader in RFID systems

DEFF Research Database (Denmark)

Galiotto, Carlo; Marchetti, Nicola; Prasad, Neeli R.

2010-01-01

Radio Frequency Identification (RFID) is a technology which is spreading more and more as a medium to identify, locate and track assets through the productive chain. As all the wireless communication devices sharing the same transmission channel, RFID readers and tags experience collisions whenever...... deployed over the same area. In this work, the RFID reader collision problem is studied and a centralized scheduling-based algorithm is proposed as possible candidate solution, especially for those scenarios involving static or low mobility readers. Taking into account the circuitry limitations of the tags......, which do not allow to use frequency or code division multiple access schemes in the RFID systems, this paper proposes an algorithm aiming to prevent the readers collisions, while keeping the access delay of the readers to the channel possibly low. The simulation results show that this algorithm performs...

Multiple optical code-label processing using multi-wavelength frequency comb generator and multi-port optical spectrum synthesizer.

Science.gov (United States)

Moritsuka, Fumi; Wada, Naoya; Sakamoto, Takahide; Kawanishi, Tetsuya; Komai, Yuki; Anzai, Shimako; Izutsu, Masayuki; Kodate, Kashiko

2007-06-11

In optical packet switching (OPS) and optical code division multiple access (OCDMA) systems, label generation and processing are key technologies. Recently, several label processors have been proposed and demonstrated. However, in order to recognize N different labels, N separate devices are required. Here, we propose and experimentally demonstrate a large-scale, multiple optical code (OC)-label generation and processing technology based on multi-port, a fully tunable optical spectrum synthesizer (OSS) and a multi-wavelength electro-optic frequency comb generator. The OSS can generate 80 different OC-labels simultaneously and can perform 80-parallel matched filtering. We also demonstrated its application to OCDMA.

A Unified Buffering Management with Set Divisible Cache for PCM Main Memory

Institute of Scientific and Technical Information of China (English)

Mei-Ying Bian; Su-Kyung Yoon; Jeong-Geun Kim; Sangjae Nam; Shin-Dug Kim

2016-01-01

This research proposes a phase-change memory (PCM) based main memory system with an effective combi-nation of a superblock-based adaptive buffering structure and its associated set divisible last-level cache (LLC). To achieve high performance similar to that of dynamic random-access memory (DRAM) based main memory, the superblock-based adaptive buffer (SABU) is comprised of dual DRAM buffers, i.e., an aggressive superblock-based pre-fetching buffer (SBPB) and an adaptive sub-block reusing buffer (SBRB), and a set divisible LLC based on a cache space optimization scheme. According to our experiment, the longer PCM access latency can typically be hidden using our proposed SABU, which can significantly reduce the number of writes over the PCM main memory by 26.44%. The SABU approach can reduce PCM access latency up to 0.43 times, compared with conventional DRAM main memory. Meanwhile, the average memory energy consumption can be reduced by 19.7%.

High-Spatial-Multiplicity Multicore Fibers for Future Dense Space-Division-Multiplexing Systems

DEFF Research Database (Denmark)

Matsuo, Shoichiro; Takenaga, Katsuhiro; Sasaki, Yusuke

2016-01-01

Multicore fibers and few-mode fibers have potential application in realizing dense-space-division multiplexing systems. However, there are some tradeoff requirements for designing the fibers. In this paper, the tradeoff requirements such as spatial channel count, crosstalk, differential mode dela...

Channel capacity of TDD-OFDM-MIMO for multiple access points in a wireless single-frequency-network

DEFF Research Database (Denmark)

Takatori, Y.; Fitzek, Frank; Tsunekawa, K.

2005-01-01

MIMO data transmission scheme, which combines Single-Frequency-Network (SFN) with TDD-OFDM-MIMO applied for wireless LAN networks. In our proposal, we advocate to use SFN for multiple access points (MAP) MIMO data transmission. The goal of this approach is to achieve very high channel capacity in both......The multiple-input-multiple-output (MIMO) technique is the most attractive candidate to improve the spectrum efficiency in the next generation wireless communication systems. However, the efficiency of MIMO techniques reduces in the line of sight (LOS) environments. In this paper, we propose a new...

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

Science.gov (United States)

Li, Hantao; Liu, Kai; Zhang, Jun

2005-11-01

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

Digital signal processing for wireless communication using Matlab

CERN Document Server

Gopi, E S

2016-01-01

This book examines signal processing techniques used in wireless communication illustrated by using the Matlab program. The author discusses these techniques as they relate to Doppler spread; delay spread; Rayleigh and Rician channel modeling; rake receiver; diversity techniques; MIMO and OFDM -based transmission techniques; and array signal processing. Related topics such as detection theory, link budget, multiple access techniques, and spread spectrum are also covered.   ·         Illustrates signal processing techniques involved in wireless communication using Matlab ·         Discusses multiple access techniques such as Frequency division multiple access, Time division multiple access, and Code division multiple access ·         Covers band pass modulation techniques such as Binary phase shift keying, Differential phase shift keying, Quadrature phase shift keying, Binary frequency shift keying, Minimum shift keying, and Gaussian minimum shift keying.

Effective use of multibeam antenna and space-time multiple access technology in modern mobile communication systems

OpenAIRE

Moskalets, N. V.

2015-01-01

A possibility for efficient use of radio-frequency spectrum and of corresponding increase in productivity of mobile communication system with space-time multiple access obtained by use of multibeam antenna of base station is considered.

Combined Radix-10 and Radix-16 Division Unit

DEFF Research Database (Denmark)

Lang, Tomas; Nannarelli, Alberto

2007-01-01

In this work we extend a previously proposed digit-recurrence radix-10 division unit to be able to perform also radix-16 division. The extension is simplified by the fact that in the radix-10 implementation the quotient digit is decomposed into two parts and that this decomposition is also...... the selection constants. The rest of the modifications relate to the generation of multiples, to the carry-save adder, to the carry-propagate adder, and to the on-the-fly conversion and rounding. The implementation results show that the delay of an iteration is similar to that of the radix-10 case...

A Novel Medium Access Control for Ad hoc Networks Based on OFDM System

Institute of Scientific and Technical Information of China (English)

YU Yi-fan; YIN Chang-chuan; YUE Guang-xin

2005-01-01

Recently, hosts of Medium Access Control (MAC) protocols for Ad hoc radio networks have been proposed to solve the hidden terminal problem and exposed terminal problem. However most of them take into no account the interactions between physical (PHY) system and MAC protocol. Therefore, the current MAC protocols are either inefficient in the networks with mobile nodes and fading channel or difficult in hardware implementation. In this paper, we present a novel media access control for Ad hoc networks that integrates a media access control protocol termed as Dual Busy Tone Multiple Access (DBTMA) into Orthogonal Frequency Division Multiplexing (OFDM) system proposed in IEEE 802.11a standard. The analysis presented in the paper indicates that the proposed MAC scheme achieves performance improvement over IEEE 802.11 protocol about 25%～80% especially in the environment with high mobility and deep fading. The complexity of the proposed scheme is also lower than other implementation of similar busy tone solution. Furthermore, it is compatible with IEEE 802.11a networks.

Distributed Medium Access Control with SDMA Support for WLANs

Science.gov (United States)

Zhou, Sheng; Niu, Zhisheng

With simultaneous multi-user transmissions, spatial division multiple access (SDMA) provides substantial throughput gain over the single user transmission. However, its implementation in WLANs with contention-based IEEE 802.11 MAC remains challenging. Problems such as coordinating and synchronizing the multiple users need to be solved in a distributed way. In this paper, we propose a distributed MAC protocol for WLANs with SDMA support. A dual-mode CTS responding mechanism is designed to accomplish the channel estimation and user synchronization required for SDMA. We analytically study the throughput performance of the proposed MAC, and dynamic parameter adjustment is designed to enhance the protocol efficiency. In addition, the proposed MAC protocol does not rely on specific physical layer realizations, and can work on legacy IEEE 802.11 equipment with slight software updates. Simulation results show that the proposed MAC outperforms IEEE 802.11 significantly, and that the dynamic parameter adjustment can effectively track the load variation in the network.

Performance analysis of commercial multiple-input-multiple-output access point in distributed antenna system.

Science.gov (United States)

Fan, Yuting; Aighobahi, Anthony E; Gomes, Nathan J; Xu, Kun; Li, Jianqiang

2015-03-23

In this paper, we experimentally investigate the throughput of IEEE 802.11n 2x2 multiple-input-multiple-output (MIMO) signals in a radio-over-fiber-based distributed antenna system (DAS) with different fiber lengths and power imbalance. Both a MIMO-supported access point (AP) and a spatial-diversity-supported AP were separately employed in the experiments. Throughput measurements were carried out with wireless users at different locations in a typical office environment. For the different fiber length effect, the results indicate that MIMO signals can maintain high throughput when the fiber length difference between the two remote antenna units (RAUs) is under 100 m and falls quickly when the length difference is greater. For the spatial diversity signals, high throughput can be maintained even when the difference is 150 m. On the other hand, the separation of the MIMO antennas allows additional freedom in placing the antennas in strategic locations for overall improved system performance, although it may also lead to received power imbalance problems. The results show that the throughput performance drops in specific positions when the received power imbalance is above around 13 dB. Hence, there is a trade-off between the extent of the wireless coverage for moderate bit-rates and the area over which peak bit-rates can be achieved.

A polarization-division multiplexing SSB-OFDM system with beat interference cancellation receivers

Science.gov (United States)

Yang, Peiling; Ma, Jianxin; Zhang, Junyi

2018-06-01

In this paper, we have proposed a polarization-division multiplexing (PDM) single-sideband optical orthogonal frequency division multiplexing (SSB-OOFDM) scheme with signal-signal beat interference cancellation receivers with balanced detection (ICRBD). This system can double channel capacity and improve spectrum efficiency (SE) with the reduced guard band (GB) due to the PDM. Multiple input multiple output (MIMO) technique is used to solve polarization mode dispersion (PMD) associated with channel estimation and equalization. By simulation, we demonstrate the efficacy of the proposed technique for a 2 ×40 Gbit/s 16-QAM SSB-PDM-OOFDM system according to the error vector magnitude (EVM) and the constellation diagrams.

Variable Delay With Directly-Modulated R-SOA and Optical Filters for Adaptive Antenna Radio-Fiber Access

DEFF Research Database (Denmark)

Prince, Kamau; Presi, Marco; Chiuchiarelli, Andrea

2009-01-01

types of signals defined in IEEE 802.16 (WiMAX) standard for wireless networks: a 90 Mbps single-carrier signal (64-QAM at 2.4 GHz) and a 78 Mbps multitone orthogonal frequency-division multiple access (OFDMA) signal. The power budget of this configuration supports a 4-element antenna array....... on a directly-modulated reflective emiconductor amplifier (R-SOA) and exploits the interplay between transmission-line dispersion and tunable optical filtering to achieve flexible true time delay, with $2pi$ beam steering at the different antennas. The system was characterized, then successfully tested with two...

The stem cell division theory of cancer.

Science.gov (United States)

López-Lázaro, Miguel

2018-03-01

All cancer registries constantly show striking differences in cancer incidence by age and among tissues. For example, lung cancer is diagnosed hundreds of times more often at age 70 than at age 20, and lung cancer in nonsmokers occurs thousands of times more frequently than heart cancer in smokers. An analysis of these differences using basic concepts in cell biology indicates that cancer is the end-result of the accumulation of cell divisions in stem cells. In other words, the main determinant of carcinogenesis is the number of cell divisions that the DNA of a stem cell has accumulated in any type of cell from the zygote. Cell division, process by which a cell copies and separates its cellular components to finally split into two cells, is necessary to produce the large number of cells required for living. However, cell division can lead to a variety of cancer-promoting errors, such as mutations and epigenetic mistakes occurring during DNA replication, chromosome aberrations arising during mitosis, errors in the distribution of cell-fate determinants between the daughter cells, and failures to restore physical interactions with other tissue components. Some of these errors are spontaneous, others are promoted by endogenous DNA damage occurring during quiescence, and others are influenced by pathological and environmental factors. The cell divisions required for carcinogenesis are primarily caused by multiple local and systemic physiological signals rather than by errors in the DNA of the cells. As carcinogenesis progresses, the accumulation of DNA errors promotes cell division and eventually triggers cell division under permissive extracellular environments. The accumulation of cell divisions in stem cells drives not only the accumulation of the DNA alterations required for carcinogenesis, but also the formation and growth of the abnormal cell populations that characterize the disease. This model of carcinogenesis provides a new framework for understanding the

Achievable Rate of a Cognitive MIMO Multiple Access Channel With Multi-Secondary Users

KAUST Repository

Sboui, Lokman; Ghazzai, Hakim; Rezki, Zouheir; Alouini, Mohamed-Slim

2015-01-01

We study the secondary sum-rate of an underlay cognitive multiple access channel consisting of a primary user and multiple secondary users (SUs) communicating with a common destination. We propose a particular linear precoding and SU selection scheme that maximize the cognitive sum-rate. This scheme is based on space alignment strategy allowing SUs to share the spectrum without interfering with each other. We derive the optimal power allocation for each selected SU after applying perfect or imperfect successive interference cancellation. Numerical results show that the proposed scheme provides a significant sum-rate improvement as the number of SUs increases. In addition, it achieves almost the same performance as an exhaustive search selection, mainly in low and high power ranges. © 1997-2012 IEEE.

Achievable Rate of a Cognitive MIMO Multiple Access Channel With Multi-Secondary Users

KAUST Repository

Sboui, Lokman

2015-03-01

We study the secondary sum-rate of an underlay cognitive multiple access channel consisting of a primary user and multiple secondary users (SUs) communicating with a common destination. We propose a particular linear precoding and SU selection scheme that maximize the cognitive sum-rate. This scheme is based on space alignment strategy allowing SUs to share the spectrum without interfering with each other. We derive the optimal power allocation for each selected SU after applying perfect or imperfect successive interference cancellation. Numerical results show that the proposed scheme provides a significant sum-rate improvement as the number of SUs increases. In addition, it achieves almost the same performance as an exhaustive search selection, mainly in low and high power ranges. © 1997-2012 IEEE.

Nonadditivity of quantum capacities of quantum multiple-access channels and the butterfly network

International Nuclear Information System (INIS)

Huang Peng; He Guangqiang; Zhu Jun; Zeng Guihua

2011-01-01

Multipartite quantum information transmission without additional classical resources is investigated. We show purely quantum superadditivity of quantum capacity regions of quantum memoryless multiple-access (MA) channels, which are not entanglement breaking. Also, we find that the superadditivity holds when the MA channel extends to the quantum butterfly network, which can achieve quantum network coding. The present widespread effects for the channels which enable entanglement distribution have not been revealed for multipartite scenarios.

ADNP-CSMA Random Multiple Access protocol application with the function of monitoring in Ad Hoc network

Directory of Open Access Journals (Sweden)

Zhan Gang

2016-01-01

Full Text Available In Ad Hoc networks,the net work of mobile nodes exchange information with their wireless transceiver equipment,the network throughput is in increased,compared to other such multiple hops network.Moreover along with the rapid development of modern information,communication business also will be increase.However,the access and adaptive of previous CSMA protocol are insufficient.According to these properties,this paper presents a kind of adaptive dual clock with monitoring function P-CSMA random multiple access protocol(ADNP-CSMA,and discusses two kinds of P-CSMA.ACK with monitoring function is introduced to maintain the stability of the whole system,and the introduction of dual clock mechanism reduces the channel of idle period.It calculate the system throughput expression through the method of average period,and the simulation results show that the system is constant in the case of high load throughput.

28 CFR 17.13 - National Security Division; interpretation of Executive Orders.

Science.gov (United States)

2010-07-01

... for National Security, who shall refer such questions to the Office of Legal Counsel, as appropriate... 28 Judicial Administration 1 2010-07-01 2010-07-01 false National Security Division... NATIONAL SECURITY INFORMATION AND ACCESS TO CLASSIFIED INFORMATION Administration § 17.13 National Security...

Modelling cell division and endoreduplication in tomato fruit pericarp

NARCIS (Netherlands)

Apri, M.; Kromdijk, J.; Visser, de P.H.B.; Gee, de M.; Molenaar, J.

2014-01-01

In many developing plant tissues and organs, differentiating cells switch from the classical cell cycle to an alternative partial cycle. This partial cycle bypasses mitosis and allows for multiple rounds of genome duplication without cell division, giving rise to cells with high ploidy numbers. This

High-Capacity Multi-Core Fibers for Space-Division Multiplexing

DEFF Research Database (Denmark)

Ye, Feihong

The transmission capacity of the present optical fiber communication systems based on time division multiplexing (TDM) and wavelength-division multiplexing (WDM) using single-mode fibers (SMFs) is reaching its limit of around 100 Tbit/s per fiber due to the fiber nonlinearities, fiber fuse...... phenomenon and the optical amplifier bandwidth. To meet the ever increasing global data traffic growth and to overcome the looming capacity crunch, a new multiplexing technology using new optical fibers is urgently needed. Space-division multiplexing (SDM) is a promising scheme to overcome the capacity limit...... of the present SMF-based systems. Among the proposed SDM schemes, the one based on uncoupled multi-core fibers (MCFs) having multiple cores in a mutual cladding has proven effective in substantially increasing the transmission capacity per fiber with least system complexity as demonstrated in several state...

Multiple-Input Multiple-Output OFDM with Index Modulation

OpenAIRE

Basar, Ertugrul

2015-01-01

Orthogonal frequency division multiplexing with index modulation (OFDM-IM) is a novel multicarrier transmission technique which has been proposed as an alternative to classical OFDM. The main idea of OFDM-IM is the use of the indices of the active subcarriers in an OFDM system as an additional source of information. In this work, we propose multiple-input multiple-output OFDM-IM (MIMO-OFDM-IM) scheme by combining OFDM-IM and MIMO transmission techniques. The low complexity transceiver structu...

Capacity Bounds for the Gaussian IM-DD Optical Multiple-Access Channel

KAUST Repository

Chaaban, Anas; Al-Ebraheemy, Omer M. S.; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

2017-01-01

Optical wireless communications (OWC) is a promising technology for closing the mismatch between the growing number of connected devices and the limited wireless network capabilities. Similar to downlink, uplink can also benefit from OWC for establishing connectivity between such devices and an optical access point. In this context, the incoherent intensitymodulation and direct-detection (IM-DD) scheme is desirable in practice. Hence, it is important to understand the fundamental limits of communication rates over an OWC uplink employing IM-DD, i.e., the channel capacity. This uplink, modeled as a Gaussian multiple-access channel (MAC) for indoors OWC, is studied in this paper, under the IM-DD constraints which form the main difference with the standard Gaussian MAC commonly studied in the radio-frequency context. Capacity region outer and inner bounds for this channel are derived. The bounds are fairly close at high signal-to-noise ratio (SNR), where a truncated- Gaussian input distribution achieves the capacity region within a constant gap. Furthermore, the bounds coincide at low SNR showing the optimality of on-off keying combined with successive cancellation decoding in this regime. At moderate SNR, an optimized uniformly-spaced discrete input distribution achieves fairly good performance.

Capacity Bounds for the Gaussian IM-DD Optical Multiple-Access Channel

KAUST Repository

Chaaban, Anas

2017-03-18

Optical wireless communications (OWC) is a promising technology for closing the mismatch between the growing number of connected devices and the limited wireless network capabilities. Similar to downlink, uplink can also benefit from OWC for establishing connectivity between such devices and an optical access point. In this context, the incoherent intensitymodulation and direct-detection (IM-DD) scheme is desirable in practice. Hence, it is important to understand the fundamental limits of communication rates over an OWC uplink employing IM-DD, i.e., the channel capacity. This uplink, modeled as a Gaussian multiple-access channel (MAC) for indoors OWC, is studied in this paper, under the IM-DD constraints which form the main difference with the standard Gaussian MAC commonly studied in the radio-frequency context. Capacity region outer and inner bounds for this channel are derived. The bounds are fairly close at high signal-to-noise ratio (SNR), where a truncated- Gaussian input distribution achieves the capacity region within a constant gap. Furthermore, the bounds coincide at low SNR showing the optimality of on-off keying combined with successive cancellation decoding in this regime. At moderate SNR, an optimized uniformly-spaced discrete input distribution achieves fairly good performance.

Cell division control by the Chromosomal Passenger Complex

Energy Technology Data Exchange (ETDEWEB)

Waal, Maike S. van der; Hengeveld, Rutger C.C.; Horst, Armando van der; Lens, Susanne M.A., E-mail: s.m.a.lens@umcutrecht.nl

2012-07-15

The Chromosomal Passenger Complex (CPC) consisting of Aurora B kinase, INCENP, Survivin and Borealin, is essential for genomic stability by controlling multiple processes during both nuclear and cytoplasmic division. In mitosis it ensures accurate segregation of the duplicated chromosomes by regulating the mitotic checkpoint, destabilizing incorrectly attached spindle microtubules and by promoting the axial shortening of chromosomal arms in anaphase. During cytokinesis the CPC most likely prevents chromosome damage by imposing an abscission delay when a chromosome bridge connects the two daughter cells. Moreover, by controlling proper cytoplasmic division, the CPC averts tetraploidization. This review describes recent insights on how the CPC is capable of conducting its various functions in the dividing cell to ensure chromosomal stability.

Particle Filtering for Multiple Access DS/CDMA Systems DS/CDMA Channel Estimation

Directory of Open Access Journals (Sweden)

Rafael Oliveira Ribeiro

2013-09-01

Full Text Available This article discusses computational implementation aspects and performance of a Bayesian methodology, namely particle filter (PF. The PF channel estimation technique is directly applied to the channel coefficients estimation of DS/CDMA systems. Simulation results for non-line-of-sight (NLOS Rayleigh fading channel propagation have indicated that the bootstrap PF estimator is capable to provide RMSE in the range of [10-3 ; 10-2] for a wide range of multiple access interference (MAI levels and signal-noise ratio (SNR, and still be able to offer robustness to near-far ratio (NFR effect.

INO80 Chromatin Remodeling Coordinates Metabolic Homeostasis with Cell Division

Directory of Open Access Journals (Sweden)

Graeme J. Gowans

2018-01-01

Full Text Available Adaptive survival requires the coordination of nutrient availability with expenditure of cellular resources. For example, in nutrient-limited environments, 50% of all S. cerevisiae genes synchronize and exhibit periodic bursts of expression in coordination with respiration and cell division in the yeast metabolic cycle (YMC. Despite the importance of metabolic and proliferative synchrony, the majority of YMC regulators are currently unknown. Here, we demonstrate that the INO80 chromatin-remodeling complex is required to coordinate respiration and cell division with periodic gene expression. Specifically, INO80 mutants have severe defects in oxygen consumption and promiscuous cell division that is no longer coupled with metabolic status. In mutant cells, chromatin accessibility of periodic genes, including TORC1-responsive genes, is relatively static, concomitant with severely attenuated gene expression. Collectively, these results reveal that the INO80 complex mediates metabolic signaling to chromatin to restrict proliferation to metabolically optimal states.

A new two dimensional spectral/spatial multi-diagonal code for noncoherent optical code division multiple access (OCDMA) systems

Science.gov (United States)

Kadhim, Rasim Azeez; Fadhil, Hilal Adnan; Aljunid, S. A.; Razalli, Mohamad Shahrazel

2014-10-01

A new two dimensional codes family, namely two dimensional multi-diagonal (2D-MD) codes, is proposed for spectral/spatial non-coherent OCDMA systems based on the one dimensional MD code. Since the MD code has the property of zero cross correlation, the proposed 2D-MD code also has this property. So that, the multi-access interference (MAI) is fully eliminated and the phase induced intensity noise (PIIN) is suppressed with the proposed code. Code performance is analyzed in terms of bit error rate (BER) while considering the effect of shot noise, PIIN, and thermal noise. The performance of the proposed code is compared with the related MD, modified quadratic congruence (MQC), two dimensional perfect difference (2D-PD) and two dimensional diluted perfect difference (2D-DPD) codes. The analytical and the simulation results reveal that the proposed 2D-MD code outperforms the other codes. Moreover, a large number of simultaneous users can be accommodated at low BER and high data rate.

Nonorthogonal multiple access and carrierless amplitude phase modulation for flexible multiuser provisioning in 5G mobile networks

NARCIS (Netherlands)

Altabas, J.A.; Rommel, S.; Puerta, R.; Izquierdo, D.; Ignacio Garces, J.; Antonio Lazaro, J.; Vegas Olmos, J.J.; Tafur Monroy, I.

2017-01-01

In this paper, a combined nonorthogonal multiple access (NOMA) and multiband carrierless amplitude phase modulation (multiCAP) scheme is proposed for capacity enhancement of and flexible resource provisioning in 5G mobile networks. The proposed scheme is experimentally evaluated over a W-band

Post-Coma Persons with Extensive Multiple Disabilities Use Microswitch Technology to Access Selected Stimulus Events or Operate a Radio Device

Science.gov (United States)

Lancioni, Giulio E.; Singh, Nirbhay N.; O'Reilly, Mark F.; Sigafoos, Jeff; Alberti, Gloria; Oliva, Doretta; Megna, Gianfranco; Iliceto, Carla; Damiani, Sabino; Ricci, Irene; Spica, Antonella

2011-01-01

The present two studies extended research evidence on the use of microswitch technology by post-coma persons with multiple disabilities. Specifically, Study I examined whether three adults with a diagnosis of minimally conscious state and multiple disabilities could use microswitches as tools to access brief, selected stimulus events. Study II…

Demonstration of hybrid orbital angular momentum multiplexing and time-division multiplexing passive optical network.

Science.gov (United States)

Wang, Andong; Zhu, Long; Liu, Jun; Du, Cheng; Mo, Qi; Wang, Jian

2015-11-16

Mode-division multiplexing passive optical network (MDM-PON) is a promising scheme for next-generation access networks to further increase fiber transmission capacity. In this paper, we demonstrate the proof-of-concept experiment of hybrid mode-division multiplexing (MDM) and time-division multiplexing (TDM) PON architecture by exploiting orbital angular momentum (OAM) modes. Bidirectional transmissions with 2.5-Gbaud 4-level pulse amplitude modulation (PAM-4) downstream and 2-Gbaud on-off keying (OOK) upstream are demonstrated in the experiment. The observed optical signal-to-noise ratio (OSNR) penalties for downstream and upstream transmissions at a bit-error rate (BER) of 2 × 10(-3) are less than 2.0 dB and 3.0 dB, respectively.

Statistical Analysis of Coherent Ultrashort Light Pulse CDMA With Multiple Optical Amplifiers Using Additive Noise Model

Science.gov (United States)

Jamshidi, Kambiz; Salehi, Jawad A.

2005-05-01

This paper describes a study of the performance of various configurations for placing multiple optical amplifiers in a typical coherent ultrashort light pulse code-division multiple access (CULP-CDMA) communication system using the additive noise model. For this study, a comprehensive performance analysis was developed that takes into account multiple-access noise, noise due to optical amplifiers, and thermal noise using the saddle-point approximation technique. Prior to obtaining the overall system performance, the input/output statistical models for different elements of the system such as encoders/decoders,star coupler, and optical amplifiers were obtained. Performance comparisons between an ideal and lossless quantum-limited case and a typical CULP-CDMA with various losses exhibit more than 30 dB more power requirement to obtain the same bit-error rate (BER). Considering the saturation effect of optical amplifiers, this paper discusses an algorithm for amplifiers' gain setting in various stages of the network in order to overcome the nonlinear effects on signal modulation in optical amplifiers. Finally, using this algorithm,various configurations of multiple optical amplifiers in CULP-CDMA are discussed and the rules for the required optimum number of amplifiers are shown with their corresponding optimum locations to be implemented along the CULP-CDMA system.

Multiple Intimate Partner Violence Experiences: Knowledge, Access, Utilization and Barriers to Utilization of Resources by Women of the African Diaspora.

Science.gov (United States)

Sabri, Bushra; Huerta, Julia; Alexander, Kamila A; St Vil, Noelle M; Campbell, Jacquelyn C; Callwood, Gloria B

2015-11-01

This study examined knowledge, access, utilization, and barriers to use of resources among Black women exposed to multiple types of intimate partner violence in Baltimore, Maryland and the U.S. Virgin Islands (USVI). We analyzed quantitative survey data collected by 163 women recruited from primary care, prenatal or family planning clinics in Baltimore and the USVI. In addition we analyzed qualitative data from in-depth interviews with 11 women. Quantitative data were analyzed using descriptive statistics and qualitative data were analyzed using thematic analysis. A substantial proportion of Black women with multiple types of violence experiences lacked knowledge of, did not have access to, and did not use resources. Barriers to resource use were identified at the individual, relationship, and community levels. There is need for programs to develop awareness, promote access and utilization of resources, and eliminate barriers to resource use among abused Black women.

Allocation and management issues in multiple-transaction open access transmission networks

Science.gov (United States)

Tao, Shu

This thesis focuses on some key issues related to allocation and management by the independent grid operator (IGO) of unbundled services in multiple-transaction open access transmission networks. The three unbundled services addressed in the thesis are transmission real power losses, reactive power support requirements from generation sources, and transmission congestion management. We develop the general framework that explicitly represents multiple transactions undertaken simultaneously in the transmission grid. This framework serves as the basis for formulating various problems treated in the thesis. We use this comprehensive framework to develop a physical-flow-based mechanism to allocate the total transmission losses to each transaction using the system. An important property of the allocation scheme is its capability to effectively deal with counter flows that result in the presence of specific transactions. Using the loss allocation results as the basis, we construct the equivalent loss compensation concept and apply it to develop flexible and effective procedures for compensating losses in multiple-transaction networks. We present a new physical-flow-based mechanism for allocating the reactive power support requirements provided by generators in multiple-transaction networks. The allocatable reactive support requirements are formulated as the sum of two specific components---the voltage magnitude variation component and the voltage angle variation component. The formulation utilizes the multiple-transaction framework and makes use of certain simplifying approximations. The formulation leads to a natural allocation as a function of the amount of each transaction. The physical interpretation of each allocation as a sensitivity of the reactive output of a generator is discussed. We propose a congestion management allocation scheme for multiple-transaction networks. The proposed scheme determines the allocation of congestion among the transactions on a physical

Modular time division multiplexer: Efficient simultaneous characterization of fast and slow transients in multiple samples

Science.gov (United States)

Kim, Stephan D.; Luo, Jiajun; Buchholz, D. Bruce; Chang, R. P. H.; Grayson, M.

2016-09-01

A modular time division multiplexer (MTDM) device is introduced to enable parallel measurement of multiple samples with both fast and slow decay transients spanning from millisecond to month-long time scales. This is achieved by dedicating a single high-speed measurement instrument for rapid data collection at the start of a transient, and by multiplexing a second low-speed measurement instrument for slow data collection of several samples in parallel for the later transients. The MTDM is a high-level design concept that can in principle measure an arbitrary number of samples, and the low cost implementation here allows up to 16 samples to be measured in parallel over several months, reducing the total ensemble measurement duration and equipment usage by as much as an order of magnitude without sacrificing fidelity. The MTDM was successfully demonstrated by simultaneously measuring the photoconductivity of three amorphous indium-gallium-zinc-oxide thin films with 20 ms data resolution for fast transients and an uninterrupted parallel run time of over 20 days. The MTDM has potential applications in many areas of research that manifest response times spanning many orders of magnitude, such as photovoltaics, rechargeable batteries, amorphous semiconductors such as silicon and amorphous indium-gallium-zinc-oxide.

Phase division multiplexed EIT for enhanced temporal resolution.

Science.gov (United States)

Dowrick, T; Holder, D

2018-03-29

The most commonly used EIT paradigm (time division multiplexing) limits the temporal resolution of impedance images due to the need to switch between injection electrodes. Advances have previously been made using frequency division multiplexing (FDM) to increase temporal resolution, but in cases where a fixed range of frequencies is available, such as imaging fast neural activity, an upper limit is placed on the total number of simultaneous injections. The use of phase division multiplexing (PDM) where multiple out of phase signals can be injected at each frequency is investigated to increase temporal resolution. TDM, FDM and PDM were compared in head tank experiments, to compare transfer impedance measurements and spatial resolution between the three techniques. A resistor phantom paradigm was established to investigate the imaging of one-off impedance changes, of magnitude 1% and with durations as low as 500 µs (similar to those seen in nerve bundles), using both PDM and TDM approaches. In head tank experiments, a strong correlation (r  >  0.85 and p  EIT injections.

WATER TEMPERATURE and other data from MULTIPLE SHIPS from 1983-01-01 to 1992-12-31 (NODC Accession 9400224)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains data collected as part of Shipboard Environmental data Acquisition System (SEAS) II program. The cruises were conducted using multiple ships....

Space-division-multiplexed transmission of 3x3 multiple-input multiple-output wireless signals over conventional graded-index multimode fiber

NARCIS (Netherlands)

Lei, Yi; Li, Jianqiang; Fan, Yuting; Yu, Dawei; Fu, Songnian; Yin, Feifei; Dai, Yitang; Xu, Kun

2016-01-01

In this paper, we experimentally demonstrate space-division-multiplexed (SDM) transmission of IEEE 802.11ac-compliant 3-spatial-stream WLAN signals over 3 spatial modes of conventional 50um graded-index (GI) multimode fiber (MMF) employing non-mode-selective 3D-waveguide photonic lantern. Two kinds

The 91st Infantry in World War I -- Analysis of an AEF Division’s Efforts to Achieve Battlefield Success

Science.gov (United States)

2013-06-13

collaboration with John J. Pershing, “Who Won the War” ( Typescript copy held in the Duane N. Diedrich Collection, Clements Library, University of...trusted to luck.”74 73The Training and Employment of Divisions, 1918, 71. 74Diary of Lieutenant Charles H. Paul, 364th Infantry, 91st Division ( typescript ...accessed 19 May 2013). Diary of Gaylen Snow, 362nd Infantry, 91st Division. Typescript held at Brigham Young University, UT. 79 Diary of Lieutenant

Topology-selective jamming of fully-connected, code-division random-access networks

Science.gov (United States)

Polydoros, Andreas; Cheng, Unjeng

1990-01-01

The purpose is to introduce certain models of topology selective stochastic jamming and examine its impact on a class of fully-connected, spread-spectrum, slotted ALOHA-type random access networks. The theory covers dedicated as well as half-duplex units. The dominant role of the spatial duty factor is established, and connections with the dual concept of time selective jamming are discussed. The optimal choices of coding rate and link access parameters (from the users' side) and the jamming spatial fraction are numerically established for DS and FH spreading.

Integrated cladding-pumped multicore few-mode erbium-doped fibre amplifier for space-division-multiplexed communications

Science.gov (United States)

Chen, H.; Jin, C.; Huang, B.; Fontaine, N. K.; Ryf, R.; Shang, K.; Grégoire, N.; Morency, S.; Essiambre, R.-J.; Li, G.; Messaddeq, Y.; Larochelle, S.

2016-08-01

Space-division multiplexing (SDM), whereby multiple spatial channels in multimode and multicore optical fibres are used to increase the total transmission capacity per fibre, is being investigated to avert a data capacity crunch and reduce the cost per transmitted bit. With the number of channels employed in SDM transmission experiments continuing to rise, there is a requirement for integrated SDM components that are scalable. Here, we demonstrate a cladding-pumped SDM erbium-doped fibre amplifier (EDFA) that consists of six uncoupled multimode erbium-doped cores. Each core supports three spatial modes, which enables the EDFA to amplify a total of 18 spatial channels (six cores × three modes) simultaneously with a single pump diode and a complexity similar to a single-mode EDFA. The amplifier delivers >20 dBm total output power per core and <7 dB noise figure over the C-band. This cladding-pumped EDFA enables combined space-division and wavelength-division multiplexed transmission over multiple multimode fibre spans.

Temperature, salinity, nutrients, and meteorological data collected from 1926 to 1991 aboard multiple platforms in Caspian Sea (NODC Accession 0072200)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0072200 contains temperature, salinity, nutrients, and meteorological data collected from 1926 to 1991 aboard multiple platforms in Caspian Sea.

Optical power allocation for adaptive transmissions in wavelength-division multiplexing free space optical networks

Directory of Open Access Journals (Sweden)

Hui Zhou

2015-08-01

Full Text Available Attracting increasing attention in recent years, the Free Space Optics (FSO technology has been recognized as a cost-effective wireless access technology for multi-Gigabit rate wireless networks. Radio on Free Space Optics (RoFSO provides a new approach to support various bandwidth-intensive wireless services in an optical wireless link. In an RoFSO system using wavelength-division multiplexing (WDM, it is possible to concurrently transmit multiple data streams consisting of various wireless services at very high rate. In this paper, we investigate the problem of optical power allocation under power budget and eye safety constraints for adaptive WDM transmission in RoFSO networks. We develop power allocation schemes for adaptive WDM transmissions to combat the effect of weather turbulence on RoFSO links. Simulation results show that WDM RoFSO can support high data rates even over long distance or under bad weather conditions with an adequate system design.

An Adaptive Time-Spread Multiple-Access Policy for Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Konstantinos Oikonomou

2007-05-01

Full Text Available Sensor networks require a simple and efficient medium access control policy achieving high system throughput with no or limited control overhead in order to increase the network lifetime by minimizing the energy consumed during transmission attempts. Time-spread multiple-access (TSMA policies that have been proposed for ad hoc network environments, can also be employed in sensor networks, since no control overhead is introduced. However, they do not take advantage of any cross-layer information in order to exploit the idiosyncrasies of the particular sensor network environment such as the presence of typically static nodes and a common destination for the forwarded data. An adaptive probabilistic TSMA-based policy, that is proposed and analyzed in this paper, exploits these idiosyncrasies and achieves higher system throughput than the existing TSMA-based policies without any need for extra control overhead. As it is analytically shown in this paper, the proposed policy always outperforms the existing TSMA-based policies, if certain parameter values are properly set; the analysis also provides for these proper values. It is also shown that the proposed policy is characterized by a certain convergence period and that high system throughput is achieved for long convergence periods. The claims and expectations of the provided analysis are supported by simulation results presented in this paper.

Interdependence of bacterial cell division and genome segregation and its potential in drug development.

Science.gov (United States)

Misra, Hari S; Maurya, Ganesh K; Chaudhary, Reema; Misra, Chitra S

2018-03-01

Cell division and genome segregation are mutually interdependent processes, which are tightly linked with bacterial multiplication. Mechanisms underlying cell division and the cellular machinery involved are largely conserved across bacteria. Segregation of genome elements on the other hand, follows different pathways depending upon its type and the functional components encoded on these elements. Small molecules, that are known to inhibit cell division and/or resolution of intertwined circular chromosome and maintenace of DNA topology have earlier been tested as antibacterial agents. The utility of such drugs in controlling bacterial infections has witnessed only partial success, possibly due to functional redundancy associated with targeted components. However, in due course, literature has grown with newer information. This review has brought forth some recent findings on bacterial cell division with special emphasis on crosstalk between cell division and genome segregation that could be explored as novel targets in drug development. Copyright © 2018 Elsevier GmbH. All rights reserved.

White matter damage impairs access to consciousness in multiple sclerosis.

Science.gov (United States)

Reuter, Françoise; Del Cul, Antoine; Malikova, Irina; Naccache, Lionel; Confort-Gouny, Sylviane; Cohen, Laurent; Cherif, André Ali; Cozzone, Patrick J; Pelletier, Jean; Ranjeva, Jean-Philippe; Dehaene, Stanislas; Audoin, Bertrand

2009-01-15

Global neuronal workspace theory predicts that damage to long-distance white matter (WM) tracts should impair access to consciousness during the perception of brief stimuli. To address this issue, we studied visual backward masking in 18 patients at the very first clinical stage of multiple sclerosis (MS), a neurological disease characterized by extensive WM damage, and in 18 matched healthy subjects. In our masking paradigm, the visibility of a digit stimulus increases non-linearly as a function of the interval duration between this target and a subsequent mask. In order to characterize quantitatively, for each subject, the transition between non-conscious and conscious perception of the stimulus, we used non-linear regression to fit a sigmoid curve to objective performance and subjective visibility reports as a function of target-mask delay. The delay corresponding to the inflexion point of the sigmoid, where visibility suddenly increases, was termed the "non-linear transition threshold" and used as a summary measure of masking efficiency. Objective and subjective non-linear transition thresholds were highly correlated across subjects in both groups, and were higher in patients compared to controls. In patients, variations in the non-linear transition threshold were inversely correlated to the Magnetization transfer ratio (MTR) values inside the right dorsolateral prefrontal WM, the right occipito-frontal fasciculus and the left cerebellum. This study provides clinical evidence of a relationship between impairments of conscious access and integrity of large WM bundles, particularly involving prefrontal cortex, as predicted by global neuronal workspace theory.

On Low-Complexity Full-diversity Detection In Multi-User MIMO Multiple-Access Channels

KAUST Repository

Ismail, Amr

2014-01-28

Multiple-input multiple-output (MIMO) techniques are becoming commonplace in recent wireless communication standards. This newly introduced dimension (i.e., space) can be efficiently used to mitigate the interference in the multi-user MIMO context. In this paper, we focus on the uplink of a MIMO multiple access channel (MAC) where perfect channel state information (CSI) is only available at the destination. We provide new sufficient conditions for a wide range of space-time block codes (STBC)s to achieve full-diversity under partial interference cancellation group decoding (PICGD) with or without successive interference cancellation (SIC) for completely blind users. Interference cancellation (IC) schemes for two and three users are then provided and shown to satisfy the full-diversity criteria. Beside the complexity reduction due to the fact that PICGD enables separate decoding of distinct users without sacrificing the diversity gain, further reduction of the decoding complexity may be obtained. In fact, thanks to the structure of the proposed schemes, the real and imaginary parts of each user\\'s symbols may be decoupled without any loss of performance. Our new IC scheme is shown to outperform recently proposed two-user IC scheme especially for high spectral efficiency while requiring significantly less decoding complexity.

On Low-Complexity Full-diversity Detection In Multi-User MIMO Multiple-Access Channels

KAUST Repository

Ismail, Amr; Alouini, Mohamed-Slim

2014-01-01

Multiple-input multiple-output (MIMO) techniques are becoming commonplace in recent wireless communication standards. This newly introduced dimension (i.e., space) can be efficiently used to mitigate the interference in the multi-user MIMO context. In this paper, we focus on the uplink of a MIMO multiple access channel (MAC) where perfect channel state information (CSI) is only available at the destination. We provide new sufficient conditions for a wide range of space-time block codes (STBC)s to achieve full-diversity under partial interference cancellation group decoding (PICGD) with or without successive interference cancellation (SIC) for completely blind users. Interference cancellation (IC) schemes for two and three users are then provided and shown to satisfy the full-diversity criteria. Beside the complexity reduction due to the fact that PICGD enables separate decoding of distinct users without sacrificing the diversity gain, further reduction of the decoding complexity may be obtained. In fact, thanks to the structure of the proposed schemes, the real and imaginary parts of each user's symbols may be decoupled without any loss of performance. Our new IC scheme is shown to outperform recently proposed two-user IC scheme especially for high spectral efficiency while requiring significantly less decoding complexity.

Computational Fair Division

DEFF Research Database (Denmark)

Branzei, Simina

Fair division is a fundamental problem in economic theory and one of the oldest questions faced through the history of human society. The high level scenario is that of several participants having to divide a collection of resources such that everyone is satisfied with their allocation -- e.g. two...... heirs dividing a car, house, and piece of land inherited. The literature on fair division was developed in the 20th century in mathematics and economics, but computational work on fair division is still sparse. This thesis can be seen as an excursion in computational fair division divided in two parts....... The first part tackles the cake cutting problem, where the cake is a metaphor for a heterogeneous divisible resource such as land, time, mineral deposits, and computer memory. We study the equilibria of classical protocols and design an algorithmic framework for reasoning about their game theoretic...

The Border Multiple

DEFF Research Database (Denmark)

of European borders by looking at border practices in the light of the mobility turn, and thus as dynamic, multiple, diverse and best expressed in everyday experiences of people living at and with borders, rather than focusing on static territorial divisions between states and regions at geopolitical level...

Cross-layer design for radio resource allocation based on priority scheduling in OFDMA wireless access network

Directory of Open Access Journals (Sweden)

Chen Yen-Wen

2011-01-01

Full Text Available Abstract The orthogonal frequency-division multiple access (OFDMA system has the advantages of flexible subcarrier allocation and adaptive modulation with respect to channel conditions. However, transmission overhead is required in each frame to broadcast the arrangement of radio resources to all mobile stations within the coverage of the same base station. This overhead greatly affects the utilization of valuable radio resources. In this paper, a cross layer scheme is proposed to reduce the number of traffic bursts at the downlink of an OFDMA wireless access network so that the overhead of the media access protocol (MAP field can be minimized. The proposed scheme considers the priorities and the channel conditions of quality of service (QoS traffic streams to arrange for them to be sent with minimum bursts in a heuristic manner. In addition, the trade-off between the degradation of the modulation level and the reduction of traffic bursts is investigated. Simulation results show that the proposed scheme can effectively reduce the traffic bursts and, therefore, increase resource utilization.

Solving Multiple Isolated, Interleaved, and Blended Tasks through Modular Neuroevolution.

Science.gov (United States)

Schrum, Jacob; Miikkulainen, Risto

2016-01-01

Many challenging sequential decision-making problems require agents to master multiple tasks. For instance, game agents may need to gather resources, attack opponents, and defend against attacks. Learning algorithms can thus benefit from having separate policies for these tasks, and from knowing when each one is appropriate. How well this approach works depends on how tightly coupled the tasks are. Three cases are identified: Isolated tasks have distinct semantics and do not interact, interleaved tasks have distinct semantics but do interact, and blended tasks have regions where semantics from multiple tasks overlap. Learning across multiple tasks is studied in this article with Modular Multiobjective NEAT, a neuroevolution framework applied to three variants of the challenging Ms. Pac-Man video game. In the standard blended version of the game, a surprising, highly effective machine-discovered task division surpasses human-specified divisions, achieving the best scores to date in this game. In isolated and interleaved versions of the game, human-specified task divisions are also successful, though the best scores are surprisingly still achieved by machine discovery. Modular neuroevolution is thus shown to be capable of finding useful, unexpected task divisions better than those apparent to a human designer.

Quantifying the Chasm: Exploring the Impact of the BCS on Total Football Revenues for Division One Football Programs from 2002-2012

Science.gov (United States)

Caro, Cary A.

2014-01-01

The Bowl Championship Series served as a collection of bowl games that were designed to crown the national champion in Division One football. The BCS created two classifications of institutions in Division football, those that were granted automatic access (AQ) to the post-season games, and those that were not (non-AQ). The BCS also generated…

DCP Leading NIH Glycoscience Common Fund Program; Funding Opportunities Open | Division of Cancer Prevention

Science.gov (United States)

NCI's Division of Cancer Prevention is a leading participant for a key initiative in the National Institutes of Health (NIH) Glycoscience Common Fund program. This program supports development of accessible and affordable new tools and technologies for studying the role complex carbohydrates in health and disease. |

GSR-TDMA: A Geometric Spatial Reuse-Time Division Multiple Access MAC Protocol for Multihop Underwater Acoustic Sensor Networks

Directory of Open Access Journals (Sweden)

Changho Yun

2016-01-01

Full Text Available The nonnegligible propagation delay of acoustic signals causes spatiotemporal uncertainty that occasionally enables simultaneous, collision-free packet transmission among underwater nodes (UNs. These transmissions can be handled by efficiently managing the channel access of the UNs in the data-link layer. To this end, Geometric Spatial Reuse-TDMA (GSR-TDMA, a new TDMA-based MAC protocol, is designed for use in centralized, multihop underwater acoustic sensor networks (UASNs, and in this case all UNs are periodically scheduled after determining a geometric map according to the information on their location. The scheduling strategy increases the number of UNs that send packets coincidentally via two subscheduling configurations (i.e., interhop and intrahop scheduling. Extensive simulations are used to investigate the reception success rate (RSR and the multihop delay (MHD of GSR-TDMA, and the results are compared to those of previous approaches, including C-MAC and HSR-TDMA. GSR-TDMA outperforms C-MAC; the RSR of GSR-TDMA is 15% higher than that of C-MAC, and the MHD of GSR-TDMA is 30% lower than that of C-MAC at the most. In addition, GSR-TDMA provides even better performance improvements over HSR-TDMA; the RSR of GSR-TDMA is 50% higher than that of HSR-TDMA, and the MHD of GSR-TDMA is an order of 102 lower than that of HSR-TDMA at the most.

Division of Finance Homepage

Science.gov (United States)

Top Department of Administration logo Alaska Department of Administration Division of Finance Search Search the Division of Finance site DOF State of Alaska Finance Home Content Area Accounting Charge Cards You are here Administration / Finance Division of Finance Updates IRIS Expenditure Object Codes

A Survivable Wavelength Division Multiplexing Passive Optical Network with Both Point-to-Point Service and Broadcast Service Delivery

Science.gov (United States)

Ma, Xuejiao; Gan, Chaoqin; Deng, Shiqi; Huang, Yan

2011-11-01

A survivable wavelength division multiplexing passive optical network enabling both point-to-point service and broadcast service is presented and demonstrated. This architecture provides an automatic traffic recovery against feeder and distribution fiber link failure, respectively. In addition, it also simplifies the protection design for multiple services transmission in wavelength division multiplexing passive optical networks.

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

Science.gov (United States)

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.

A Comparative Study of Multiplexing Schemes for Next Generation Optical Access Networks

Science.gov (United States)

Imtiaz, Waqas A.; Khan, Yousaf; Shah, Pir Mehar Ali; Zeeshan, M.

2014-09-01

Passive optical network (PON) is a high bandwidth, economical solution which can provide the necessary bandwidth to end-users. Wavelength division multiplexed passive optical networks (WDM PONs) and time division multiplexed passive optical networks (TDM PONs) are considered as an evolutionary step for next-generation optical access (NGOA) networks. However they fail to provide highest transmission capacity, efficient bandwidth access, and robust dispersion tolerance. Thus future PONs are considered on simpler, efficient and potentially scalable, optical code division multiplexed (OCDM) PONs. This paper compares the performance of existing PONs with OCDM PON to determine a suitable scheme for NGOA networks. Two system parameter are used in this paper: fiber length, and bit rate. Performance analysis using Optisystem shows that; for a sufficient system performance parameters i.e. bit error rate (BER) ≤ 10-9, and maximum quality factor (Q) ≥ 6, OCDMA PON efficiently performs upto 50 km with 10 Gbit/s per ONU.

Multiple Coaxial Catheter System for Reliable Access in Interventional Stroke Therapy

International Nuclear Information System (INIS)

Kulcsar, Zsolt; Yilmaz, Hasan; Bonvin, Christophe; Lovblad, Karl O.; Ruefenacht, Daniel A.

2010-01-01

In some patients with acute cerebral vessel occlusion, navigating mechanical thrombectomy systems is difficult due to tortuous anatomy of the aortic arch, carotid arteries, or vertebral arteries. Our purpose was to describe a multiple coaxial catheter system used for mechanical revascularization that helps navigation and manipulations in tortuous vessels. A triple or quadruple coaxial catheter system was built in 28 consecutive cases presenting with acute ischemic stroke. All cases were treated by mechanical thrombectomy with the Penumbra System. In cases of unsuccessful thrombo-aspiration, additional thrombolysis or angioplasty with stent placement was used for improving recanalization. The catheter system consisted of an outermost 8-Fr and an intermediate 6-Fr guiding catheter, containing the inner Penumbra reperfusion catheters. The largest, 4.1-Fr, reperfusion catheter was navigated over a Prowler Select Plus microcatheter. The catheter system provided access to reach the cerebral lesions and provided stability for the mechanically demanding manipulations of thromboaspiration and stent navigation in all cases. Apart from their mechanical role, the specific parts of the system could also provide access to different types of interventions, like carotid stenting through the 8-Fr guiding catheter and intracranial stenting and thrombolysis through the Prowler Select Plus microcatheter. In this series, there were no complications related to the catheter system. In conclusion, building up a triple or quadruple coaxial system proved to be safe and efficient in our experience for the mechanical thrombectomy treatment of acute ischemic stroke.

Novel Equalization Techniques for Space Division Multiplexing Based on Stokes Space Update Rule

Directory of Open Access Journals (Sweden)

Francisco Javier Vaquero Caballero

2017-02-01

Full Text Available Space division multiplexing (SDM is a promising technology that aims to overcome the capacity crunch of optical communications. In this paper, we introduce the multiple-input multiple-output (MIMO Stokes Space Algorithm (SSA implemented in frequency domain, a novel equalization technique for space division multiplexing (SDM. Although different papers have been published about the SSA and its MIMO implementation, we provide for the first time an analysis of the of the convergence speed and frequency offset of the SSA compared to the least mean square (LMS. SSA algorithm can deal with higher frequency offsets and linewidths than LMS, being suitable for optical communications with higher phase noise. SSA does not need pre-compensation of frequency offset, which can be compensated after equalization without penalties. On the other hand, due to reduced convergence speed, SSA requires longer training sequences than LMS.

Cell Division Synchronization

Science.gov (United States)

The report summarizes the progress in the design and construction of automatic equipment for synchronizing cell division in culture by periodic...Concurrent experiments in hypothermic synchronization of algal cell division are reported.

Improved MIMO radar GMTI via cyclic-shift transmission of orthogonal frequency division signals

Science.gov (United States)

Li, Fuyou; He, Feng; Dong, Zhen; Wu, Manqing

2018-05-01

Minimum detectable velocity (MDV) and maximum detectable velocity are both important in ground moving target indication (GMTI) systems. Smaller MDV can be achieved by longer baseline via multiple-input multiple-output (MIMO) radar. Maximum detectable velocity is decided by blind velocities associated with carrier frequencies, and blind velocities can be mitigated by orthogonal frequency division signals. However, the scattering echoes from different carrier frequencies are independent, which is not good for improving MDV performance. An improved cyclic-shift transmission is applied in MIMO GMTI system in this paper. MDV performance is improved due to the longer baseline, and maximum detectable velocity performance is improved due to the mitigation of blind velocities via multiple carrier frequencies. The signal model for this mode is established, the principle of mitigating blind velocities with orthogonal frequency division signals is presented; the performance of different MIMO GMTI waveforms is analysed; and the performance of different array configurations is analysed. Simulation results by space-time-frequency adaptive processing proves that our proposed method is a valid way to improve GMTI performance.

Access Request Trustworthiness in Weighted Access Control Framework

Institute of Scientific and Technical Information of China (English)

WANG Lun-wei; LIAO Xiang-ke; WANG Huai-min

2005-01-01

Weighted factor is given to access control policies to express the importance of policy and its effect on access control decision. According to this weighted access control framework, a trustworthiness model for access request is also given. In this model, we give the measure of trustworthiness factor to access request, by using some idea of uncertainty reasoning of expert system, present and prove the parallel propagation formula of request trustworthiness factor among multiple policies, and get the final trustworthiness factor to decide whether authorizing. In this model, authorization decision is given according to the calculation of request trustworthiness factor, which is more understandable, more suitable for real requirement and more powerful for security enhancement than traditional methods. Meanwhile the finer access control granularity is another advantage.

Argonne Physics Division Colloquium

Science.gov (United States)

[Argonne Logo] [DOE Logo] Physics Division Home News Division Information Contact PHY Org Chart Physics Division Colloquium Auditorium, Building 203, Argonne National Laboratory Fridays at 11:00 AM 2017 : Sereres Johnston 15 Sep 2017 Joint Physics and Materials Science Colloquium J. C. Séamus Davis, Cornell

Multiple Off-Ice Performance Variables Predict On-Ice Skating Performance in Male and Female Division III Ice Hockey Players

Directory of Open Access Journals (Sweden)

effrey M. Janot, Nicholas M. Beltz, Lance D. Dalleck

2015-09-01

Full Text Available The purpose of this study was to determine if off-ice performance variables could predict on-ice skating performance in Division III collegiate hockey players. Both men (n = 15 and women (n = 11 hockey players (age = 20.5 ± 1.4 years participated in the study. The skating tests were agility cornering S-turn, 6.10 m acceleration, 44.80 m speed, modified repeat skate, and 15.20 m full speed. Off-ice variables assessed were years of playing experience, height, weight and percent body fat and off-ice performance variables included vertical jump (VJ, 40-yd dash (36.58m, 1-RM squat, pro-agility, Wingate peak power and peak power percentage drop (% drop, and 1.5 mile (2.4km run. Results indicated that 40-yd dash (36.58m, VJ, 1.5 mile (2.4km run, and % drop were significant predictors of skating performance for repeat skate (slowest, fastest, and average time and 44.80 m speed time, respectively. Four predictive equations were derived from multiple regression analyses: 1 slowest repeat skate time = 2.362 + (1.68 x 40-yd dash time + (0.005 x 1.5 mile run, 2 fastest repeat skate time = 9.762 - (0.089 x VJ - (0.998 x 40-yd dash time, 3 average repeat skate time = 7.770 + (1.041 x 40-yd dash time - (0.63 x VJ + (0.003 x 1.5 mile time, and 4 47.85 m speed test = 7.707 - (0.050 x VJ - (0.01 x % drop. It was concluded that selected off-ice tests could be used to predict on-ice performance regarding speed and recovery ability in Division III male and female hockey players.

Nonadditivity of quantum and classical capacities for entanglement breaking multiple-access channels and the butterfly network

International Nuclear Information System (INIS)

Grudka, Andrzej; Horodecki, Pawel

2010-01-01

We analyze quantum network primitives which are entanglement breaking. We show superadditivity of quantum and classical capacity regions for quantum multiple-access channels and the quantum butterfly network. Since the effects are especially visible at high noise they suggest that quantum information effects may be particularly helpful in the case of the networks with occasional high noise rates. The present effects provide a qualitative borderline between superadditivities of bipartite and multipartite systems.

Division-Free Multiquantization Scheme for Modern Video Codecs

Directory of Open Access Journals (Sweden)

Mousumi Das

2012-01-01

Full Text Available The current trend of digital convergence leads to the need of the video encoder/decoder (codec that should support multiple video standards on a single platform as it is expensive to use dedicated video codec chip for each standard. The paper presents a high performance circuit shared architecture that can perform the quantization of five popular video codecs such as H.264/AVC, AVS, VC-1, MPEG-2/4, and JPEG. The proposed quantizer architecture is completely division-free as the division operation is replaced by shift and addition operations for all the standards. The design is implemented on FPGA and later synthesized in CMOS 0.18 μm technology. The results show that the proposed design satisfies the requirement of all five codecs with a maximum decoding capability of 60 fps at 187 MHz on Xilinx FPGA platform for 1080 p HD video.

Secure Degrees of Freedom Regions of Multiple Access and Interference Channels: The Polytope Structure

OpenAIRE

Xie, Jianwei; Ulukus, Sennur

2014-01-01

The sum secure degrees of freedom (s.d.o.f.) of two fundamental multi-user network structures, the K-user Gaussian multiple access (MAC) wiretap channel and the K-user interference channel (IC) with secrecy constraints, have been determined recently as K(K-1)/(K(K-1)+1) [1,2] and K(K-1)/(2K-1) [3,4], respectively. In this paper, we determine the entire s.d.o.f. regions of these two channel models. The converse for the MAC follows from a middle step in the converse of [1,2]. The converse for t...

Divisible ℤ-modules

Directory of Open Access Journals (Sweden)

Futa Yuichi

2016-03-01

Full Text Available In this article, we formalize the definition of divisible ℤ-module and its properties in the Mizar system [3]. We formally prove that any non-trivial divisible ℤ-modules are not finitely-generated.We introduce a divisible ℤ-module, equivalent to a vector space of a torsion-free ℤ-module with a coefficient ring ℚ. ℤ-modules are important for lattice problems, LLL (Lenstra, Lenstra and Lovász base reduction algorithm [15], cryptographic systems with lattices [16] and coding theory [8].

Multiple-Antenna Interference Cancellation for WLAN with MAC Interference Avoidance in Open Access Networks

Directory of Open Access Journals (Sweden)

Alexandr M. Kuzminskiy

2007-10-01

Full Text Available The potential of multiantenna interference cancellation receiver algorithms for increasing the uplink throughput in WLAN systems such as 802.11 is investigated. The medium access control (MAC in such systems is based on carrier sensing multiple-access with collision avoidance (CSMA/CA, which itself is a powerful tool for the mitigation of intrasystem interference. However, due to the spatial dependence of received signal strengths, it is possible for the collision avoidance mechanism to fail, resulting in packet collisions at the receiver and a reduction in system throughput. The CSMA/CA MAC protocol can be complemented in such scenarios by interference cancellation (IC algorithms at the physical (PHY layer. The corresponding gains in throughput are a result of the complex interplay between the PHY and MAC layers. It is shown that semiblind interference cancellation techniques are essential for mitigating the impact of interference bursts, in particular since these are typically asynchronous with respect to the desired signal burst. Semiblind IC algorithms based on second- and higher-order statistics are compared to the conventional no-IC and training-based IC techniques in an open access network (OAN scenario involving home and visiting users. It is found that the semiblind IC algorithms significantly outperform the other techniques due to the bursty and asynchronous nature of the interference caused by the MAC interference avoidance scheme.

Multiple-Antenna Interference Cancellation for WLAN with MAC Interference Avoidance in Open Access Networks

Directory of Open Access Journals (Sweden)

Kuzminskiy Alexandr M

2007-01-01

Full Text Available The potential of multiantenna interference cancellation receiver algorithms for increasing the uplink throughput in WLAN systems such as 802.11 is investigated. The medium access control (MAC in such systems is based on carrier sensing multiple-access with collision avoidance (CSMA/CA, which itself is a powerful tool for the mitigation of intrasystem interference. However, due to the spatial dependence of received signal strengths, it is possible for the collision avoidance mechanism to fail, resulting in packet collisions at the receiver and a reduction in system throughput. The CSMA/CA MAC protocol can be complemented in such scenarios by interference cancellation (IC algorithms at the physical (PHY layer. The corresponding gains in throughput are a result of the complex interplay between the PHY and MAC layers. It is shown that semiblind interference cancellation techniques are essential for mitigating the impact of interference bursts, in particular since these are typically asynchronous with respect to the desired signal burst. Semiblind IC algorithms based on second- and higher-order statistics are compared to the conventional no-IC and training-based IC techniques in an open access network (OAN scenario involving home and visiting users. It is found that the semiblind IC algorithms significantly outperform the other techniques due to the bursty and asynchronous nature of the interference caused by the MAC interference avoidance scheme.

A New Time-Hopping Multiple Access Communication System Simulator: Application to Ultra-Wideband

Directory of Open Access Journals (Sweden)

José M. Páez-Borrallo

2005-03-01

Full Text Available Time-hopping ultra-wideband technology presents some very attractive features for future indoor wireless systems in terms of achievable transmission rate and multiple access capabilities. This paper develops an algorithm to design time-hopping system simulators specially suitable for ultra-wideband, which takes advantage of some of the specific characteristics of this kind of systems. The algorithm allows an improvement of both the time capabilities and the achievable sampling rate and can be used to research into the influence of different parameters on the performance of the system. An additional result is the validation of a new general performance formula for time-hopping ultra-wideband systems with multipath channels.

Embedding Open Access into the European Landscape – the Contribution of LIBER

Directory of Open Access Journals (Sweden)

Paul Ayris

2007-08-01

Full Text Available This paper continues an earlier published history of the OAI Workshops, organised under the aegis of the LIBER Access Division, in CERN Geneva. It discusses the OAI5 Workshop, held on 18-20 April 2007, which underlines the emerging importance of Open Access to support information provision and exchange across Europe.

Radio resource management in multi-tier cellular wireless networks

CERN Document Server

Hossain, Ekram; Niyato, Dusit

2013-01-01

Providing an extensive overview of the radio resource management problem in femtocell networks, this invaluable book considers both code division multiple access femtocells and orthogonal frequency-division multiple access femtocells. In addition to incorporating current research on this topic, the book also covers technical challenges in femtocell deployment, provides readers with a variety of approaches to resource allocation and a comparison of their effectiveness, explains how to model various networks using Stochastic geometry and shot noise theory, and much more.

Development of a USB-based multi-channel time division scaler for HL-2A

International Nuclear Information System (INIS)

Liang Ping

2008-01-01

HL-2A is China's first Tokamak device with divertor configuration. Mastering the process and plasma parameter changes with time are of great significance to achieve controlled nuclear fusion. In the recent upgrading of HL-2A, for which a higher and faster electronic equipment was required, we developed a new type USB multi-channel time division scaler for HL-2A including functions: USB interface, PC graphical user interface, simultaneously calibrating more than five channel signals, optional time division spacing 2-50 ms, count rate up to over 2 MHz, accessing all the information 20 s after a activated signal, and processing data and displaying off-line. (authors)

Creating a Context for Learning: Activating Children’s Whole Number Knowledge Prepares Them to Understand Fraction Division

Directory of Open Access Journals (Sweden)

Pooja Gupta Sidney

2017-07-01

Full Text Available When children learn about fractions, their prior knowledge of whole numbers often interferes, resulting in a whole number bias. However, many fraction concepts are generalizations of analogous whole number concepts; for example, fraction division and whole number division share a similar conceptual structure. Drawing on past studies of analogical transfer, we hypothesize that children’s whole number division knowledge will support their understanding of fraction division when their relevant prior knowledge is activated immediately before engaging with fraction division. Children in 5th and 6th grade modeled fraction division with physical objects after modeling a series of addition, subtraction, multiplication, and division problems with whole number operands and fraction operands. In one condition, problems were blocked by operation, such that children modeled fraction problems immediately after analogous whole number problems (e.g., fraction division problems followed whole number division problems. In another condition, problems were blocked by number type, such that children modeled all four arithmetic operations with whole numbers in the first block, and then operations with fractions in the second block. Children who solved whole number division problems immediately before fraction division problems were significantly better at modeling the conceptual structure of fraction division than those who solved all of the fraction problems together. Thus, implicit analogies across shared concepts can affect children’s mathematical thinking. Moreover, specific analogies between whole number and fraction concepts can yield a positive, rather than a negative, whole number bias.

Department of Energy: MICS (Mathematical Information, and Computational Sciences Division). High performance computing and communications program

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-06-01

This document is intended to serve two purposes. Its first purpose is that of a program status report of the considerable progress that the Department of Energy (DOE) has made since 1993, the time of the last such report (DOE/ER-0536, {open_quotes}The DOE Program in HPCC{close_quotes}), toward achieving the goals of the High Performance Computing and Communications (HPCC) Program. The second purpose is that of a summary report of the many research programs administered by the Mathematical, Information, and Computational Sciences (MICS) Division of the Office of Energy Research under the auspices of the HPCC Program and to provide, wherever relevant, easy access to pertinent information about MICS-Division activities via universal resource locators (URLs) on the World Wide Web (WWW). The information pointed to by the URL is updated frequently, and the interested reader is urged to access the WWW for the latest information.

Physics division annual report - 1999

International Nuclear Information System (INIS)

Thayer, K.

2000-01-01

This report summarizes the research performed in the past year in the Argonne Physics Division. The Division's programs include operation of ATLAS as a national heavy-ion user facility, nuclear structure and reaction research with beams of heavy ions, accelerator research and development especially in superconducting radio frequency technology, nuclear theory and medium energy nuclear physics. The Division took significant strides forward in its science and its initiatives for the future in the past year. Major progress was made in developing the concept and the technology for the future advanced facility of beams of short-lived nuclei, the Rare Isotope Accelerator. The scientific program capitalized on important instrumentation initiatives with key advances in nuclear science. In 1999, the nuclear science community adopted the Argonne concept for a multi-beam superconducting linear accelerator driver as the design of choice for the next major facility in the field a Rare Isotope Accelerator (RIA) as recommended by the Nuclear Science Advisory Committee's 1996 Long Range Plan. Argonne has made significant R and D progress on almost all aspects of the design concept including the fast gas catcher (to allow fast fragmentation beams to be stopped and reaccelerated) that in large part, defined the RIA concept the superconducting rf technology for the driver accelerator, the multiple-charge-state concept (to permit the facility to meet the design intensity goals with existing ion-source technology), and designs and tests of high-power target concepts to effectively deal with the full beam power of the driver linac. An NSAC subcommittee recommended the Argonne concept and set as tie design goal Uranium beams of 100-kwatt power at 400 MeV/u. Argonne demonstrated that this goal can be met with an innovative, but technically in-hand, design

Division of atomic physics

International Nuclear Information System (INIS)

Kroell, S.

1994-01-01

The Division of Atomic Physics, Lund Institute of Technology (LTH), is responsible for the basic physics teaching in all subjects at LTH and for specialized teaching in Optics, Atomic Physics, Atomic and Molecular Spectroscopy and Laser Physics. The Division has research activities in basic and applied optical spectroscopy, to a large extent based on lasers. It is also part of the Physics Department, Lund University, where it forms one of eight divisions. Since the beginning of 1980 the research activities of our division have been centred around the use of lasers. The activities during the period 1991-1992 is described in this progress reports

Effects of mathematics computer games on special education students’ multiplicative reasoning ability

NARCIS (Netherlands)

Bakker, M.|info:eu-repo/dai/nl/355337770; Van den Heuvel-Panhuizen, M.|info:eu-repo/dai/nl/069266255; Robitzsch, Alexander

2016-01-01

This study examined the effects of a teacher-delivered intervention with online math-ematics mini-games on special education students’ multiplicative reasoning ability(multiplication and division). The games involved declarative, procedural, as well asconceptual knowledge of multiplicative

Effects of mathematics computer games on special education students' multiplicative reasoning ability

NARCIS (Netherlands)

Bakker, M.; Heuvel-Panhuizen, M.H.A.M. van den; Robitzsch, A.

2016-01-01

This study examined the effects of a teacher-delivered intervention with online mathematics mini-games on special education students' multiplicative reasoning ability (multiplication and division). The games involved declarative, procedural, as well as conceptual knowledge of multiplicative

MAC-Layer Active Dropping for Real-Time Video Streaming in 4G Access Networks

KAUST Repository

She, James

2010-12-01

This paper introduces a MAC-layer active dropping scheme to achieve effective resource utilization, which can satisfy the application-layer delay for real-time video streaming in time division multiple access based 4G broadband wireless access networks. When a video frame is not likely to be reconstructed within the application-layer delay bound at a receiver for the minimum decoding requirement, the MAC-layer protocol data units of such video frame will be proactively dropped before the transmission. An analytical model is developed to evaluate how confident a video frame can be delivered within its application-layer delay bound by jointly considering the effects of time-varying wireless channel, minimum decoding requirement of each video frame, data retransmission, and playback buffer. Extensive simulations with video traces are conducted to prove the effectiveness of the proposed scheme. When compared to conventional cross-layer schemes using prioritized-transmission/retransmission, the proposed scheme is practically implementable for more effective resource utilization, avoiding delay propagation, and achieving better video qualities under certain conditions.

Vedic division methodology for high-speed very large scale integration applications

Directory of Open Access Journals (Sweden)

Prabir Saha

2014-02-01

Full Text Available Transistor level implementation of division methodology using ancient Vedic mathematics is reported in this Letter. The potentiality of the ‘Dhvajanka (on top of the flag’ formula was adopted from Vedic mathematics to implement such type of divider for practical very large scale integration applications. The division methodology was implemented through half of the divisor bit instead of the actual divisor, subtraction and little multiplication. Propagation delay and dynamic power consumption of divider circuitry were minimised significantly by stage reduction through Vedic division methodology. The functionality of the division algorithm was checked and performance parameters like propagation delay and dynamic power consumption were calculated through spice spectre with 90 nm complementary metal oxide semiconductor technology. The propagation delay of the resulted (32 ÷ 16 bit divider circuitry was only ∼300 ns and consumed ∼32.5 mW power for a layout area of 17.39 mm^2. Combination of Boolean arithmetic along with ancient Vedic mathematics, substantial amount of iterations were reduced resulted as ∼47, ∼38, 34% reduction in delay and ∼34, ∼21, ∼18% reduction in power were investigated compared with the mostly used (e.g. digit-recurrence, Newton–Raphson, Goldschmidt architectures.

The progression of the intra-erythrocytic cell cycle of Plasmodium falciparum and the role of the centriolar plaques in asynchronous mitotic division during schizogony

DEFF Research Database (Denmark)

Arnot, David E; Ronander, Elena; Bengtsson, Dominique C

2011-01-01

The cell division cycle and mitosis of intra-erythrocytic (IE) Plasmodium falciparum are poorly understood aspects of parasite development which affect malaria molecular pathogenesis. Specifically, the timing of the multiple gap (G), DNA synthesis (S) and chromosome separation (M) phases of paras......The cell division cycle and mitosis of intra-erythrocytic (IE) Plasmodium falciparum are poorly understood aspects of parasite development which affect malaria molecular pathogenesis. Specifically, the timing of the multiple gap (G), DNA synthesis (S) and chromosome separation (M) phases...... of parasite mitosis are not well defined, nor whether genome divisions are immediately followed by cleavage of the nuclear envelope. Curiously, daughter merozoite numbers do not follow the geometric expansion expected from equal numbers of binary divisions, an outcome difficult to explain using the standard...

Annual Report to Parliament Access to Information Act - 2016-2017

International Development Research Centre (IDRC) Digital Library (Canada)

Isabelle

... the economic and social advancement of those regions.” ... Technology Division staff to ensure that access to Centre information in all forms respects the ... one came from a business, one came from academia and six came from the public. 4 ...

Applications of Fast Truncated Multiplication in Cryptography

Directory of Open Access Journals (Sweden)

Laszlo Hars

2006-12-01

Full Text Available Truncated multiplications compute truncated products, contiguous subsequences of the digits of integer products. For an n-digit multiplication algorithm of time complexity O(nα, with 1<α≤2, there is a truncated multiplication algorithm, which is constant times faster when computing a short enough truncated product. Applying these fast truncated multiplications, several cryptographic long integer arithmetic algorithms are improved, including integer reciprocals, divisions, Barrett and Montgomery multiplications, 2n-digit modular multiplication on hardware for n-digit half products. For example, Montgomery multiplication is performed in 2.6 Karatsuba multiplication time.

Technical activities, 1990: Surface Science Division

International Nuclear Information System (INIS)

Powell, C.J.

1991-05-01

The report summarizes technical activities and accomplishments of the NIST Surface Science Division during Fiscal Year 1990. Overviews are presented of the Division and of its three constituent groups: Surface Dynamical Processes, Thin Films and Interfaces, and Surface Spectroscopies and Standards. These overviews are followed by reports of selected technical accomplishments during the year. A summary is given of Division outputs and interactions that includes lists of publications, talks, committee assignments, seminars (including both Division seminars and Interface Science seminars arranged through the Division), conferences organized, and a standard reference material certified. Finally, lists are given of Division staff and of guest scientists who have worked in the Division during the past year

78 FR 48640 - Special Access Proceeding; Comment Deadline Extension

Science.gov (United States)

2013-08-09

... CONTACT: William Layton, Pricing Policy Division, Wireline Competition Bureau, 202-418-0868 or William...-198. See 44 U.S.C. 3506(c)(4). For further information, please contact William Layton, Pricing Policy... its rules for granting pricing flexibility for the special access services provided by incumbent local...

Optimizing TCP Performance in Multi-AP Residential Broadband Connections via Minislot Access

Directory of Open Access Journals (Sweden)

Domenico Giustiniano

2013-01-01

Full Text Available The high bandwidth demand of Internet applications has recently driven the need of increasing the residential download speed. A practical solution to the problem is to aggregate the bandwidth of 802.11 access points (APs backhauls in range. Since 802.11 devices are usually single radio, the communication to APs on different radio channels requires a time-division multiple access (TDMA policy at the client station. With an in-depth experimental analysis and a customized 802.11 driver, in this paper, we show that the usage of multi-AP TDMA policy may cause degradation of the TCP throughput and an underutilization of the AP backhauls. We then introduce a simple analytical model that accurately predicts the TCP round-trip time (RTT with a multi-AP TDMA policy and propose a resource allocation algorithm to reduce the observed TCP RTT with a very low computational cost. Our proposed scheme runs locally at the client station and improves the aggregate throughput up to 1.5 times compared to state-of-the-art allocations. We finally show that the throughput achieved by our algorithm is very close to the theoretical upper bound in key simulation scenarios.

PRESSURE - WATER and Other Data from MULTIPLE SHIPS and Other Platforms From World-Wide Distribution from 19950101 to 19951231 (NODC Accession 9600078)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The accession contains Salinity Temperature and Depth (STD) data in the (TESAC) format. This contains one year data that was sent as radio messages from multiple...

WATER TEMPERATURE and Other Data from MULTIPLE SHIPS From NE Atlantic (limit-40 W) and Others from 19500831 to 19881231 (NODC Accession 9200060)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains contains chlorophyll data collected from 1958-1988 using multiple ships. Marine pigments, productivity, and associated chemistry data were...

Reducing LTE Uplink Transmission Energy by Allocating Resources

DEFF Research Database (Denmark)

Lauridsen, Mads; Jensen, Anders Riis; Mogensen, Preben

2011-01-01

The effect of physical resource block (PRB) allocation on an LTE modem's transmit power and total modem energy consumption is examined. In this paper the uplink resource blocks are scheduled in either a Frequency Division Multiple Access (FDMA) or Time Division Multiple Access (TDMA) manner......, to determine if low transmission power & long transmission time or high transmission power & short transmission time is most energy efficient. It is important to minimize the LTE modem's energy consumption caused by uplink transmission because it affects phone battery time, and because researchers rarely focus...

Performance evaluation of an IMDD optical OFDM-CDMA system.

Science.gov (United States)

Mhatli, Sofien; Mrabet, Hichem; Giacoumidis, Elias; Dayoub, Iyad

2018-03-01

In this paper, we propose a modulation technique for passive optical networks that harnesses two-dimensional prime hop system optical code division multiplexing access (OCDMA) and optical orthogonal frequency-division multiplexing (OFDM) for intensity modulation with direct-detection (IMDD) to enhance users' signal capacity in a cost-effective manner. The theoretical analysis is built from an analytical formula that takes into account both multiple-access interference and photodetector noise. Results show that OFDM-OCDMA with multiple users has similar performance to single-user conventional OOFDM for low transmitted powers.

Theoretical Investigation into Spectral Coexistence of CDMA and TDMA Systems

Directory of Open Access Journals (Sweden)

A.M. Abbosh

2008-12-01

Full Text Available The scarcity of available radio spectrum presently limits the extension of modern multimedia systems. This paper presents a theoretical investigation into the possibility of using a frequency overlay of a narrowband Code Division Multiple Access (CDMA System and a Time Division Multiple Access (TDMA System to provide a greater spectral efficiency. This paper shows that under certain conditions the two systems can operate in the same frequency band and in the same area with a considerable improvement in the overall capacity of the whole system.

Why is CDMA the solution for mobile satellite communication

Science.gov (United States)

Gilhousen, Klein S.; Jacobs, Irwin M.; Padovani, Roberto; Weaver, Lindsay A.

1989-01-01

It is demonstrated that spread spectrum Code Division Multiple Access (CDMA) systems provide an economically superior solution to satellite mobile communications by increasing the system maximum capacity with respect to single channel per carrier Frequency Division Multiple Access (FDMA) systems. Following the comparative analysis of CDMA and FDMA systems, the design of a model that was developed to test the feasibility of the approach and the performance of a spread spectrum system in a mobile environment. Results of extensive computer simulations as well as laboratory and field tests results are presented.

Performance comparison between S-ALOHA and R3T protocols for multirate OFFH-CDMA systems in optical packet networks

Science.gov (United States)

Inaty, Elie; Raad, Robert; Fortier, Paul; Shalaby, Hossam M.

2006-12-01

We discuss two newly proposed multiple-access control (MAC) protocols for multirate optical code-division multiple access (OCDMA) networks. The first protocol is slotted ALOHA/optical fast-frequency-hopping code-division multiple access (S-ALOHA/OFFH-CDMA), and the second is round-robin receiver-transmitter/optical fast-frequency-hopping code-division multiple access (R3/OFFH-CDMA). Our main subject is to exploit the potential of the optical fast-frequency-hopping CDMA using a fiber Bragg grating when jointly used with two different MAC protocols in a link layer as an effective way of integrating multirate traffic. The system throughput and the average packet delay are compared for both systems. It is shown that S-ALOHA is better than R3T when the user's activity and the offered load are high, whereas R3T is better for smaller values. Both protocols can be competitive in terms of the system throughput, with the advantage going to the R3T protocol at a moderate offered load. However, the R3T protocol suffers a higher delay mainly because of the presence of additional modes. Finally, the overlapped OCDMA system always outperforms the variable processing gain (VPG) OCDMA system regardless of the protocol used.

Analysis of Coded FHSS Systems with Multiple Access Interference over Generalized Fading Channels

Directory of Open Access Journals (Sweden)

Salam A. Zummo

2009-02-01

Full Text Available We study the effect of interference on the performance of coded FHSS systems. This is achieved by modeling the physical channel in these systems as a block fading channel. In the derivation of the bit error probability over Nakagami fading channels, we use the exact statistics of the multiple access interference (MAI in FHSS systems. Due to the mathematically intractable expression of the Rician distribution, we use the Gaussian approximation to derive the error probability of coded FHSS over Rician fading channel. The effect of pilot-aided channel estimation is studied for Rician fading channels using the Gaussian approximation. From this, the optimal hopping rate in coded FHSS is approximated. Results show that the performance loss due to interference increases as the hopping rate decreases.

E-Division activities report

International Nuclear Information System (INIS)

Barschall, H.H.

1984-07-01

E (Experimental Physics) Division carries out basic and applied research in atomic and nuclear physics, in materials science, and in other areas related to the missions of the Laboratory. Some of the activities are cooperative efforts with other divisions of the Laboratory, and, in a few cases, with other laboratories. Many of the experiments are directly applicable to problems in weapons and energy, some have only potential applied uses, and others are in pure physics. This report presents abstracts of papers published by E (Experimental Physics) Division staff members between July 1983 and June 1984. In addition, it lists the members of the scientific staff of the division, including visitors and students, and some of the assignments of staff members on scientific committees. A brief summary of the budget is included

Progress report of Applied Physics Division. 1 October 1980 - 30 June 1981. Acting Division Chief - Dr. J. Parry

International Nuclear Information System (INIS)

2004-01-01

In September 1980, the Commission approved a reorganization of Physics Division, Engineering Research Division and Instrumentation and Control Division to form two new research divisions to be known as Applied Physics Division and Nuclear Technology Division. The Applied Physics Division will be responsible for applied science programs, particularly those concerned with nuclear techniques. The Division is organized as four sections with the following responsibilities: (1) Nuclear Applications and Energy Studies Section. Program includes studies in nuclear physics, nuclear applications, ion implantation and neutron scattering. (2) Semiconductor and Radiation Physics Section. Studies in semiconductor radiation detectors, radiation standards and laser applications. (3) Electronic Systems Section. This includes systems analysis, digital systems, instrument design, project instrumentation and instrument maintenance. (4) Fusion Physics Section. This covers work carried out by staff currently attached to university groups (author)

Effects of Mathematics Computer Games on Special Education Students' Multiplicative Reasoning Ability

Science.gov (United States)

Bakker, Marjoke; van den Heuvel-Panhuizen, Marja; Robitzsch, Alexander

2016-01-01

This study examined the effects of a teacher-delivered intervention with online mathematics mini-games on special education students' multiplicative reasoning ability (multiplication and division). The games involved declarative, procedural, as well as conceptual knowledge of multiplicative relations, and were accompanied with teacher-led lessons…

Division Quilts: A Measurement Model

Science.gov (United States)

Pratt, Sarah S.; Lupton, Tina M.; Richardson, Kerri

2015-01-01

As teachers seek activities to assist students in understanding division as more than just the algorithm, they find many examples of division as fair sharing. However, teachers have few activities to engage students in a quotative (measurement) model of division. Efraim Fischbein and his colleagues (1985) defined two types of whole-number…

Bandwidth Allocation Method by Service for WDM EPON

Institute of Scientific and Technical Information of China (English)

Yongseok; Chang; Changgyu; Choi; Jonghoon; Eom; Sungho; Kim

2003-01-01

A WDM(Wavelength Division Multiplexing) EPON(Ethernet Passive Optical Network) is an economical and efficient access network that has attracted significant research attention in recent years. A MAC(Media Access Control) Protocol of PON is based on TDMA(Time Division Multiple Access) basically, we can classify this protocol into a fixed length slot assignment method suitable for leased line supporting Qos(Quality of Service) and a variable length slot assignment method suitable for LAN/MAN with the best ...

Parity-Check Network Coding for Multiple Access Relay Channel in Wireless Sensor Cooperative Communications

Directory of Open Access Journals (Sweden)

Du Bing

2010-01-01

Full Text Available A recently developed theory suggests that network coding is a generalization of source coding and channel coding and thus yields a significant performance improvement in terms of throughput and spatial diversity. This paper proposes a cooperative design of a parity-check network coding scheme in the context of a two-source multiple access relay channel (MARC model, a common compact model in hierarchical wireless sensor networks (WSNs. The scheme uses Low-Density Parity-Check (LDPC as the surrogate to build up a layered structure which encapsulates the multiple constituent LDPC codes in the source and relay nodes. Specifically, the relay node decodes the messages from two sources, which are used to generate extra parity-check bits by a random network coding procedure to fill up the rate gap between Source-Relay and Source-Destination transmissions. Then, we derived the key algebraic relationships among multidimensional LDPC constituent codes as one of the constraints for code profile optimization. These extra check bits are sent to the destination to realize a cooperative diversity as well as to approach MARC decode-and-forward (DF capacity.

Comparison of Concussion Rates Between NCAA Division I and Division III Men's and Women's Ice Hockey Players.

Science.gov (United States)

Rosene, John M; Raksnis, Bryan; Silva, Brie; Woefel, Tyler; Visich, Paul S; Dompier, Thomas P; Kerr, Zachary Y

2017-09-01

Examinations related to divisional differences in the incidence of sports-related concussions (SRC) in collegiate ice hockey are limited. To compare the epidemiologic patterns of concussion in National Collegiate Athletic Association (NCAA) ice hockey by sex and division. Descriptive epidemiology study. A convenience sample of men's and women's ice hockey teams in Divisions I and III provided SRC data via the NCAA Injury Surveillance Program during the 2009-2010 to 2014-2015 academic years. Concussion counts, rates, and distributions were examined by factors including injury activity and position. Injury rate ratios (IRRs) and injury proportion ratios (IPRs) with 95% confidence intervals (CIs) were used to compare concussion rates and distributions, respectively. Overall, 415 concussions were reported for men's and women's ice hockey combined. The highest concussion rate was found in Division I men (0.83 per 1000 athlete-exposures [AEs]), followed by Division III women (0.78/1000 AEs), Division I women (0.65/1000 AEs), and Division III men (0.64/1000 AEs). However, the only significant IRR was that the concussion rate was higher in Division I men than Division III men (IRR = 1.29; 95% CI, 1.02-1.65). The proportion of concussions from checking was higher in men than women (28.5% vs 9.4%; IPR = 3.02; 95% CI, 1.63-5.59); however, this proportion was higher in Division I women than Division III women (18.4% vs 1.8%; IPR = 10.47; 95% CI, 1.37-79.75). The proportion of concussions sustained by goalkeepers was higher in women than men (14.2% vs 2.9%; IPR = 4.86; 95% CI, 2.19-10.77), with findings consistent within each division. Concussion rates did not vary by sex but differed by division among men. Checking-related concussions were less common in women than men overall but more common in Division I women than Division III women. Findings highlight the need to better understand the reasons underlying divisional differences within men's and women's ice hockey and the

Experimental demonstration of multiple-inputs multiple-outputs OFDM/OQAM visible light communications

Science.gov (United States)

Lin, Bangjiang; Tang, Xuan; Ghassemlooy, Zabih; Lin, Chun; Zhang, Min

2017-10-01

We experimentally demonstrate a 2×2 optical multiple-inputs multiple-outputs (MIMO) visible light communications system based on the modified orthogonal frequency-division multiplexing/offset quadrature amplitude modulation scheme. The adjacent subcarrier frequency-domain averaging (ASFA) with the full-loaded (FL) and half-loaded (HL) preamble structures is proposed for demultiplexing and mitigating the intrinsic imaginary interference (IMI) effect. Compared with the conventional channel estimation (CE) method, ASFA offers improved transmission performance. With the FL method, we obtain more accurate MIMO CE to mitigate the IMI effect and the optical noise compared to the HL method.

The promise of downlink MU-MIMO for high-capacity next generation mobile broadband networks based on IEEE 802.16 m

OpenAIRE

Papathanassiou Apostolos; Davydov Alexei

2011-01-01

Abstract The dramatic increase of the demand for mobile broadband services poses stringent requirements on the performance evolution of currently deployed mobile broadband networks, such as Mobile WiMAX Release 1 and 3GPP LTE Release 8. Although the combination of single-user multiple-input multiple-output (SU-MIMO) and orthogonal frequency division multiple access (OFDMA) provide the appropriate technologies for improving the downlink performance of third generation (3G) code division multip...

Physics division annual report - October 2000.

Energy Technology Data Exchange (ETDEWEB)

Thayer, K. [ed.

2000-10-16

This report summarizes the research performed in the past year in the Argonne Physics Division. The Division's programs include operation of ATLAS as a national heavy-ion user facility, nuclear structure and reaction research with beams of heavy ions, accelerator research and development especially in superconducting radio frequency technology, nuclear theory and medium energy nuclear physics. The Division took significant strides forward in its science and its initiatives for the future in the past year. Major progress was made in developing the concept and the technology for the future advanced facility of beams of short-lived nuclei, the Rare Isotope Accelerator. The scientific program capitalized on important instrumentation initiatives with key advances in nuclear science. In 1999, the nuclear science community adopted the Argonne concept for a multi-beam superconducting linear accelerator driver as the design of choice for the next major facility in the field a Rare Isotope Accelerator (RIA) as recommended by the Nuclear Science Advisory Committee's 1996 Long Range Plan. Argonne has made significant R&D progress on almost all aspects of the design concept including the fast gas catcher (to allow fast fragmentation beams to be stopped and reaccelerated) that in large part, defined the RIA concept the superconducting rf technology for the driver accelerator, the multiple-charge-state concept (to permit the facility to meet the design intensity goals with existing ion-source technology), and designs and tests of high-power target concepts to effectively deal with the full beam power of the driver linac. An NSAC subcommittee recommended the Argonne concept and set as tie design goal Uranium beams of 100-kwatt power at 400 MeV/u. Argonne demonstrated that this goal can be met with an innovative, but technically in-hand, design.

Dynamic Cognitive Self-Organized TDMA for Medium Access Control in Real-Time Vehicle to Vehicle Communications

Directory of Open Access Journals (Sweden)

Mario Manzano

2013-01-01

Full Text Available The emergence of intelligent transport systems has brought out a new set of requirements on wireless communication. To cope with these requirements, several proposals are currently under discussion. In this highly mobile environment, the design of a prompt, efficient, flexible, and reliable medium access control, able to cover the specific constraints of the named real-time communications applications, is still unsolved. This paper presents the original proposal integrating Non-Cooperative Cognitive Time Division Multiple Access (NCC-TDMA based on Cognitive Radio (CR techniques to obtain a mechanism which complies with the requirements of real-time communications. Though the proposed MAC uses a slotted channel, it can be adapted to operate on the physical layer of different standards. The authors’ analysis considers the IEEE WAVE and 802.11p as the standards of reference. The mechanism also offers other advantages, such as avoiding signalling and the adaptation capacity to channel conditions and interferences. The solution is applied to the problem of units merging a convoy. Comparison results between NCC-TDMA and Slotted-Aloha are included.

Multiuser chirp modulation for underwater acoustic channel based on VTRM

Directory of Open Access Journals (Sweden)

Fei Yuan

2017-05-01

Full Text Available In this paper, an ascheme is proposed for multiuser underwater acoustic communication by using the multi-chirp rate signals. It differs from the well known TDMA (Time Division Multiple Access, FDMA (Frequency Division Multiple Access or CDMA (Code Division Multiple Access, by assigning each users with different chirp-rate carriers instead of the time, frequency or PN code. Multi-chirp rate signals can be separated from each other by FrFT (Fractional Fourier Transform, which can be regarded as the chirp-based decomposing, and superior to the match filter in the underwater acoustic channel. VTRM (Virtual Time Reverse Mirror is applied into the system to alleviate the ISI caused by the multipatch and make the equalization more simple. Results of computer simulations and pool experiments prove that the proposed multiuser underwater acoustic communication based on the multi-chirp rate exhibit well performance. Outfield experments carrie out in Xiamen Port show that using about 10 kHz bandwidth, four users could communicate at the same time with 425 bps with low BER and can match the UAC application.

Teaching Individuals with Profound Multiple Disabilities to Access Preferred Stimuli with Multiple Microswitches

Science.gov (United States)

Tam, Gee May; Phillips, Katrina J.; Mudford, Oliver C.

2011-01-01

We replicated and extended previous research on microswitch facilitated choice making by individuals with profound multiple disabilities. Following an assessment of stimulus preferences, we taught 6 adults with profound multiple disabilities to emit 2 different responses to activate highly preferred stimuli. All participants learnt to activate…

Recent activities of the Seismology Division Early Career Representative(s)

Science.gov (United States)

Agius, Matthew; Van Noten, Koen; Ermert, Laura; Mai, P. Martin; Krawczyk, CharLotte

2016-04-01

The European Geosciences Union is a bottom-up-organisation, in which its members are represented by their respective scientific divisions, committees and council. In recent years, EGU has embarked on a mission to reach out for its numerous 'younger' members by giving awards to outstanding young scientists and the setting up of Early Career Scientists (ECS) representatives. The division representative's role is to engage in discussions that concern students and early career scientists. Several meetings between all the division representatives are held throughout the year to discuss ideas and Union-wide issues. One important impact ECS representatives have had on EGU is the increased number of short courses and workshops run by ECS during the annual General Assembly. Another important contribution of ECS representatives was redefining 'Young Scientist' to 'Early Career Scientist', which avoids discrimination due to age. Since 2014, the Seismology Division has its own ECS representative. In an effort to more effectively reach out for young seismologists, a blog and a social media page dedicated to seismology have been set up online. With this dedicated blog, we'd like to give more depth to the average browsing experience by enabling young researchers to explore various seismology topics in one place while making the field more exciting and accessible to the broader community. These pages are used to promote the latest research especially of young seismologists and to share interesting seismo-news. Over the months the pages proved to be popular, with hundreds of views every week and an increased number of followers. An online survey was conducted to learn more about the activities and needs of early career seismologists. We present the results from this survey, and the work that has been carried out over the last two years, including detail of what has been achieved so far, and what we would like the ECS representation for Seismology to achieve. Young seismologists are

ICTs and development: assessing internet and mobile phone use among the urban poor in Kawempe division, Kampala district

OpenAIRE

Namatovu, Esther

2012-01-01

Master thesis in development management- University of Agder, 2012 This study set out to understand and assess internet and mobile phone uses among the urban poor in Kawempe division in Kampala district, Uganda. As the internet and mobile phones are rapidly diffusing through communities with more people having access to them, it is important to understand what people are actually doing with their access. There has been so much optimism and scepticism among scholars around the potential of ...

Reconfigurable Radio Access Unit for DWDM to W-Band Wireless Conversion

DEFF Research Database (Denmark)

Chorchos, Łukasz; Rommel, Simon; Turkiewicz, Jarosław P.

2017-01-01

In this letter a reconfigurable Remote Access Unit (RAU) is proposed and demonstrated, interfacing dense wavelength division multiplexed (DWDM) optical and W-band wireless links. The RAU is composed of a tunable local oscillator, a narrow optical filter and a control unit, making it reconfigurable...

77 FR 40586 - Coastal Programs Division

Science.gov (United States)

2012-07-10

... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration Coastal Programs Division AGENCY: Coastal Programs Division, Office of Ocean and Coastal Resource Management, National Ocean.... FOR FURTHER INFORMATION CONTACT: Kerry Kehoe, Coastal Programs Division (NORM/3), Office of Ocean and...

Divisions of general practice in Australia: how do they measure up in the international context?

Science.gov (United States)

Smith, Judith; Sibthorpe, Beverly

2007-07-13

Since the late 1980s, there has been evidence of an international trend towards more organised primary care. This has taken a number of forms including the emergence of primary care organisations. Underpinning such developments is an inherent belief in evidence that suggests that well-developed primary care is associated with improved health outcomes and greater cost-effectiveness within health systems. In Australia, primary care organisations have emerged as divisions of general practice. These are professionally-led, regionally-based, and largely government-funded voluntary associations of general practitioners that seek to co-ordinate local primary care services, and improve the quality of care and health outcomes for local communities. In this paper, we examine and debate the development of divisions in the international context, using six roles of primary care organisations outlined in published research. The six roles that are used as the basis for the critique are the ability of primary care organisations to: improve health outcomes; manage demand and control costs; engage primary care physicians; enable greater integration of health services; develop more accessible services in community and primary care settings; and enable greater scrutiny and assurance of quality of primary care services. We conclude that there has been an evolutionary approach to divisions' development and they now appear embedded as geographically-based planning and development organisations within the Australian primary health care system. The Australian Government has to date been cautious in its approach to intervention in divisions' direction and performance. However, options for the next phase include: making greater use of contracts between government and divisions; introducing and extending proposed national quality targets for divisions, linked with financial or other incentives for performance; government sub-contracting with state-based organisations to act as purchasers of

Theoretical Division progress report

International Nuclear Information System (INIS)

Cooper, N.G.

1979-04-01

This report presents highlights of activities in the Theoretical (T) Division from October 1976-January 1979. The report is divided into three parts. Part I presents an overview of the Division: its unique function at the Los Alamos Scientific Laboratory (LASL) and within the scientific community as a whole; the organization of personnel; the main areas of research; and a survey of recent T-Division initiatives. This overview is followed by a survey of the 13 groups within the Division, their main responsibilities, interests, and expertise, consulting activities, and recent scientific accomplisments. The remainder of the report, Parts II and III, is devoted to articles on selected research activities. Recent efforts on topics of immediate interest to energy and weapons programs at LASL and elsewhere are described in Part II, Major National Programs. Separate articles present T-Divison contributions to weapons research, reactor safety and reactor physics research, fusion research, laser isotope separation, and other energy research. Each article is a compilation of independent projects within T Division, all related to but addressing different aspects of the major program. Part III is organized by subject discipline, and describes recent scientific advances of fundamental interest. An introduction, defining the scope and general nature of T-Division efforts within a given discipline, is followed by articles on the research topics selected. The reporting is done by the scientists involved in the research, and an attempt is made to communicate to a general audience. Some data are given incidentally; more technical presentations of the research accomplished may be found among the 47 pages of references. 110 figures, 5 tables

Mobile and Accessible Learning for MOOCs

Science.gov (United States)

Sharples, Mike; Kloos, Carlos Delgado; Dimitriadis, Yannis; Garlatti, Serge; Specht, Marcus

2015-01-01

Many modern web-based systems provide a "responsive" design that allows material and services to be accessed on mobile and desktop devices, with the aim of providing "ubiquitous access." Besides offering access to learning materials such as podcasts and videos across multiple locations, mobile, wearable and ubiquitous…

Prokaryotic cell division: flexible and diverse

NARCIS (Netherlands)

den Blaauwen, T.

2013-01-01

Gram-negative rod-shaped bacteria have different approaches to position the cell division initiating Z-ring at the correct moment in their cell division cycle. The subsequent maturation into a functional division machine occurs in vastly different species in two steps with appreciable time in

Flexible Access Control for Dynamic Collaborative Environments

NARCIS (Netherlands)

Dekker, M.A.C.

2009-01-01

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

Fusion energy division computer systems network

International Nuclear Information System (INIS)

Hammons, C.E.

1980-12-01

The Fusion Energy Division of the Oak Ridge National Laboratory (ORNL) operated by Union Carbide Corporation Nuclear Division (UCC-ND) is primarily involved in the investigation of problems related to the use of controlled thermonuclear fusion as an energy source. The Fusion Energy Division supports investigations of experimental fusion devices and related fusion theory. This memo provides a brief overview of the computing environment in the Fusion Energy Division and the computing support provided to the experimental effort and theory research

Department of Energy Mathematical, Information, and Computational Sciences Division: High Performance Computing and Communications Program

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-11-01

This document is intended to serve two purposes. Its first purpose is that of a program status report of the considerable progress that the Department of Energy (DOE) has made since 1993, the time of the last such report (DOE/ER-0536, The DOE Program in HPCC), toward achieving the goals of the High Performance Computing and Communications (HPCC) Program. The second purpose is that of a summary report of the many research programs administered by the Mathematical, Information, and Computational Sciences (MICS) Division of the Office of Energy Research under the auspices of the HPCC Program and to provide, wherever relevant, easy access to pertinent information about MICS-Division activities via universal resource locators (URLs) on the World Wide Web (WWW).

ParA and ParB coordinate chromosome segregation with cell elongation and division during Streptomyces sporulation

Science.gov (United States)

Donczew, Magdalena; Mackiewicz, Paweł; Wróbel, Agnieszka; Flärdh, Klas; Zakrzewska-Czerwińska, Jolanta

2016-01-01

In unicellular bacteria, the ParA and ParB proteins segregate chromosomes and coordinate this process with cell division and chromosome replication. During sporulation of mycelial Streptomyces, ParA and ParB uniformly distribute multiple chromosomes along the filamentous sporogenic hyphal compartment, which then differentiates into a chain of unigenomic spores. However, chromosome segregation must be coordinated with cell elongation and multiple divisions. Here, we addressed the question of whether ParA and ParB are involved in the synchronization of cell-cycle processes during sporulation in Streptomyces. To answer this question, we used time-lapse microscopy, which allows the monitoring of growth and division of single sporogenic hyphae. We showed that sporogenic hyphae stop extending at the time of ParA accumulation and Z-ring formation. We demonstrated that both ParA and ParB affect the rate of hyphal extension. Additionally, we showed that ParA promotes the formation of massive nucleoprotein complexes by ParB. We also showed that FtsZ ring assembly is affected by the ParB protein and/or unsegregated DNA. Our results indicate the existence of a checkpoint between the extension and septation of sporogenic hyphae that involves the ParA and ParB proteins. PMID:27248800

CAS (CHEMICAL ABSTRACTS SOCIETY) PARAMETER CODES and Other Data from MULTIPLE SHIPS From Caribbean Sea and Others from 19790205 to 19890503 (NCEI Accession 9100017)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The accession contains Chemical Abstracts Society (CAS) parameter codes and Other Data from MULTIPLE SHIPS From Caribbean Sea and Gulf of Mexico from February 5,...

Characterization and Optimization of LDPC Codes for the 2-User Gaussian Multiple Access Channel

Directory of Open Access Journals (Sweden)

Declercq David

2007-01-01

Full Text Available We address the problem of designing good LDPC codes for the Gaussian multiple access channel (MAC. The framework we choose is to design multiuser LDPC codes with joint belief propagation decoding on the joint graph of the 2-user case. Our main result compared to existing work is to express analytically EXIT functions of the multiuser decoder with two different approximations of the density evolution. This allows us to propose a very simple linear programming optimization for the complicated problem of LDPC code design with joint multiuser decoding. The stability condition for our case is derived and used in the optimization constraints. The codes that we obtain for the 2-user case are quite good for various rates, especially if we consider the very simple optimization procedure.

Coherence-Multiplexed Optical RF Feeder Networks

NARCIS (Netherlands)

Meijerink, Arjan; Taniman, R.O.; van Etten, Wim

2007-01-01

An optical RF feeding system for wireless access is proposed, in which the radio access points are distinguished by means of coherence multiplexing (CM). CM is a rather unknown and potentially inexpensive optical code division multiple access technique, which is particularly suitable for relatively

Potential of OFDM for next generation optical access

Science.gov (United States)

Fritzsche, Daniel; Weis, Erik; Breuer, Dirk

2011-01-01

This paper shows the requirements for next generation optical access (NGOA) networks and analyzes the potential of OFDM (orthogonal frequency division multiplexing) for the use in such network scenarios. First, we show the motivation for NGOA systems based on the future requirements on FTTH access systems and list the advantages of OFDM in such scenarios. In the next part, the basics of OFDM and different methods to generate and detect optical OFDM signals are explained and analyzed. At the transmitter side the options include intensity modulation and the more advanced field modulation of the optical OFDM signal. At the receiver there is the choice between direct detection and coherent detection. As the result of this discussion we show our vision of the future use of OFDM in optical access networks.

Space-division-multiplexed transmission of 3x3 multiple-input multiple-output wireless signals over conventional graded-index multimode fiber.

Science.gov (United States)

Lei, Yi; Li, Jianqiang; Fan, Yuting; Yu, Dawei; Fu, Songnian; Yin, Feifei; Dai, Yitang; Xu, Kun

2016-12-12

In this paper, we experimentally demonstrate space-division-multiplexed (SDM) transmission of IEEE 802.11ac-compliant 3-spatial-stream WLAN signals over 3 spatial modes of conventional 50um graded-index (GI) multimode fiber (MMF) employing non-mode-selective 3D-waveguide photonic lantern. Two kinds of scenarios, including fiber-only transmission and fiber-wireless hybrid transmission, were investigated by measuring error vector magnitude (EVM) performance for each stream and condition number (CN) of the channel matrix. The experimental results show that, SDM-based MMF link could offer a CNwireless MIMO signals over existing in-building commercially-available MMFs with enormous cost-saving.

49 CFR 1242.03 - Made by accounting divisions.

Science.gov (United States)

2010-10-01

... 49 Transportation 9 2010-10-01 2010-10-01 false Made by accounting divisions. 1242.03 Section 1242... accounting divisions. The separation shall be made by accounting divisions, where such divisions are maintained, and the aggregate of the accounting divisions reported for the quarter and for the year. ...

Uncorrelated multiple conductive filament nucleation and rupture in ultra-thin high-κ dielectric based resistive random access memory

KAUST Repository

Wu, Xing

2011-08-29

Resistive switching in transition metal oxides could form the basis for next-generation non-volatile memory (NVM). It has been reported that the current in the high-conductivity state of several technologically relevant oxide materials flows through localized filaments, but these filaments have been characterized only individually, limiting our understanding of the possibility of multiple conductive filaments nucleation and rupture and the correlation kinetics of their evolution. In this study, direct visualization of uncorrelated multiple conductive filaments in ultra-thin HfO2-based high-κ dielectricresistive random access memory (RRAM) device has been achieved by high-resolution transmission electron microscopy (HRTEM), along with electron energy loss spectroscopy(EELS), for nanoscale chemical analysis. The locations of these multiple filaments are found to be spatially uncorrelated. The evolution of these microstructural changes and chemical properties of these filaments will provide a fundamental understanding of the switching mechanism for RRAM in thin oxide films and pave way for the investigation into improving the stability and scalability of switching memory devices.

Analysis of Student Errors on Division of Fractions

Science.gov (United States)

Maelasari, E.; Jupri, A.

2017-02-01

This study aims to describe the type of student errors that typically occurs at the completion of the division arithmetic operations on fractions, and to describe the causes of students’ mistakes. This research used a descriptive qualitative method, and involved 22 fifth grade students at one particular elementary school in Kuningan, Indonesia. The results of this study showed that students’ error answers caused by students changing their way of thinking to solve multiplication and division operations on the same procedures, the changing of mix fractions to common fraction have made students confused, and students are careless in doing calculation. From student written work, in solving the fraction problems, we found that there is influence between the uses of learning methods and student response, and some of student responses beyond researchers’ prediction. We conclude that the teaching method is not only the important thing that must be prepared, but the teacher should also prepare about predictions of students’ answers to the problems that will be given in the learning process. This could be a reflection for teachers to be better and to achieve the expected learning goals.

2017 T Division Lightning Talks

Energy Technology Data Exchange (ETDEWEB)

Ramsey, Marilyn Leann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Abeywardhana, Jayalath AMM [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Adams, Colin Mackenzie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Adams, Luke Clyde [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carter, Austin Lewis [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ducru, Pablo Philippe [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Duignan, Thomas John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gifford, Brendan Joel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hills, Benjamin Hale [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hoffman, Kentaro Jack [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Khair, Adnan Ibne [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kochanski, Kelly Anne Pribble [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ledwith, Patrick John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Leveillee, Joshua Anthony [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lewis, Sina Genevieve [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ma, Xiaoyu [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Merians, Hugh Drake [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Moore, Bryan Alexander [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nijjar, Parmeet Kaur [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Oles, Vladyslav [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Olszewski, Maciej W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Philipbar, Brad Montgomery [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reisner, Andrew Ray [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Roberts, David Benjamin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rufa, Dominic Antonio [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sifain, Andrew E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Smith, Justin Steven [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Smith, Lauren Taylor Wisbey [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Svolos, Lampros [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Thibault, Joshua Ryan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ushijima-Mwesigwa, Hayato Montezuma [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Weaver, Claire Marie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Witzen, Wyatt Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Zentgraf, Sabine Silvia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Alred, John Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-10-06

All members of the T Division Community, students, staff members, group leaders, division management, and other interested individuals are invited to come and support the following student(s) as they present their Lightning Talks.

Division: The Sleeping Dragon

Science.gov (United States)

Watson, Anne

2012-01-01

Of the four mathematical operators, division seems to not sit easily for many learners. Division is often described as "the odd one out". Pupils develop coping strategies that enable them to "get away with it". So, problems, misunderstandings, and misconceptions go unresolved perhaps for a lifetime. Why is this? Is it a case of "out of sight out…

E-Division activities report

International Nuclear Information System (INIS)

Barschall, H.H.

1979-07-01

This report describes some of the activities in E (Experimental Physics) Division during the past year. E-Division carries out research and development in areas related to the missions of the Laboratory. Many of the activities are in pure and applied atomic and nuclear physics. In addition, this report describes work on accelerators, radiation damage, microwaves, and plasma diagnostics

Novel Coiled-Coil Cell Division Factor ZapB Stimulates Z Ring Assembly and Cell Division

DEFF Research Database (Denmark)

Ebersbach, Gitte; Galli, Elizabeth; Møller-Jensen, Jakob

2008-01-01

Formation of the Z ring is the first known event in bacterial cell division. However, it is not yet known how the assembly and contraction of the Z ring is regulated. Here, we identify a novel cell division factor ZapB in Escherichia coli that simultaneously stimulates Z ring assembly and cell...... division. Deletion of zapB resulted in delayed cell division and the formation of ectopic Z rings and spirals whereas overexpression of ZapB resulted in nucleoid condensation and aberrant cell divisions. Localization of ZapB to the divisome depended on FtsZ but not FtsA, ZipA or FtsI and ZapB interacted...... with FtsZ in a bacterial two-hybrid analysis. The simultaneous inactivation of FtsA and ZipA prevented Z ring assembly and ZapB localization. Time lapse microscopy showed that ZapB-GFP is present at mid-cell in a pattern very similar to that of FtsZ. Cells carrying a zapB deletion and the ftsZ84ts allele...

Implementasi dan Evaluasi Kinerja Multi Input SingleOutput Orthogonal Frequency Division Multiplexing (MISO OFDM Menggunakan Wireless Open Access Research Platform (WARP

Directory of Open Access Journals (Sweden)

Galih Permana Putra

2017-01-01

Full Text Available Teknologi komunikasi nirkabel terus berkembang untuk memenuhi kebutuhan manusia akan koneksi informasi yang cepat, pengiriman data yang berkapasitas besar dan dapat diandalkan. Di dalam proses tersebut banyak sekali gangguan yang dapat mempengaruhi penurunan kinerja komunikasi diantaranya adalah multipath fading [1]. Multi Input Single Output (MISO merupakan salah satu teknik space diversity yang menggunakan banyak antena dengan tujuan untuk mengatasi multipath fading. Adapun pada proses transmisi digunakan teknik Orthogonal Frequency-Division Multiplexing (OFDM yang bertujuan memberikan keuntungan dalam hal efisiensi pada saat transmisi data dan mampu menghindari Inter Simbol Interference (ISI. Pada penelitian ini akan dibandingkan kinerja sistem MISO OFDM dan SISO OFDM yang akan disimulasikan dan di implementasikan pada modul Wireless Open Access Penelitian Platform (WARP untuk mengevaluasi kinerja BER sebagai fungsi dari daya pancar dan jarak variasi. Parameter yang digunakan di dalam pengukuran berdasarkan IEEE 802.11 a/g karena menggunakan frekuensi 2,4 Ghz. Terdapat dua skema pengukuran yaitu SISO OFDM dan MISO OFDM dengan variasi jarak 4,6 dan 8 meter dengan variasi daya pancar -35 s/d -4 dBm dengan peningkatan gain 5 kali secara berkala. Dari dua skema yang dilaksanakan dapat disimpulkan bahwa semakin jauh jarak antara pemancar dan penerima maka dibutuhkan penambahan gain untuk menjaga kualitas data yang dikirimkan. Disamping itu, terdapat perbedaan nilai gain untuk mencapai nilai BER = dibutuhkan penambahan gain = - 33 sedangkan pada SISO OFM dibutuhkan penambahan gain = -18.

Ethnicity and the policing of nightclub accessibility in the Danish night-time economy

DEFF Research Database (Denmark)

Søgaard, Thomas Friis

2017-01-01

accessibility contributes to the (re)production of ethnic divisions and inequalities in nocturnal consumer spaces. Based on ethnographic research in Denmark, the article explores the key governmental rationalities informing bouncers’ exclusion of visible ethnic minority men. The article argues that bouncers...

A novel model of magnetorheological damper with hysteresis division

Science.gov (United States)

Yu, Jianqiang; Dong, Xiaomin; Zhang, Zonglun

2017-10-01

Due to the complex nonlinearity of magnetorheological (MR) behavior, the modeling of MR dampers is a challenge. A simple and effective model of MR damper remains a work in progress. A novel model of MR damper is proposed with force-velocity hysteresis division method in this study. A typical hysteresis loop of MR damper can be simply divided into two novel curves with the division idea. One is the backbone curve and the other is the branch curve. The exponential-family functions which capturing the characteristics of the two curves can simplify the model and improve the identification efficiency. To illustrate and validate the novel phenomenological model with hysteresis division idea, a dual-end MR damper is designed and tested. Based on the experimental data, the characteristics of the novel curves are investigated. To simplify the parameters identification and obtain the reversibility, the maximum force part, the non-dimensional backbone part and the non-dimensional branch part are derived from the two curves. The maximum force part and the non-dimensional part are in multiplication type add-rule. The maximum force part is dependent on the current and maximum velocity. The non-dominated sorting genetic algorithm II (NSGA II) based on the design of experiments (DOE) is employed to identify the parameters of the normalized shape functions. Comparative analysis is conducted based on the identification results. The analysis shows that the novel model with few identification parameters has higher accuracy and better predictive ability.

Object based data access at the D0 experiment

International Nuclear Information System (INIS)

Fuess, S.

1995-11-01

The D OE Experiment at Fermilab is currently participating in the FNAL Computing Division's ''Computing for Analysis Project'' (CAP) to investigate object based data storage and access. Following a short description of the CAP system architecture, the D OE data model is explored. A brief discussion of the method of operation of the CAP system leads into a concluding section

Podcast: The Electronic Crimes Division

Science.gov (United States)

Sept 26, 2016. Chris Lukas, the Special Agent in Charge of the Electronic Crimes Division within the OIG's Office of Investigations talks about computer forensics, cybercrime in the EPA and his division's role in criminal investigations.

NESDIS OSPO Data Access Policy and CRM

Science.gov (United States)

Seybold, M. G.; Donoho, N. A.; McNamara, D.; Paquette, J.; Renkevens, T.

2012-12-01

The Office of Satellite and Product Operations (OSPO) is the NESDIS office responsible for satellite operations, product generation, and product distribution. Access to and distribution of OSPO data was formally established in a Data Access Policy dated February, 2011. An extension of the data access policy is the OSPO Customer Relationship Management (CRM) Database, which has been in development since 2008 and is reaching a critical level of maturity. This presentation will provide a summary of the data access policy and standard operating procedure (SOP) for handling data access requests. The tangential CRM database will be highlighted including the incident tracking system, reporting and notification capabilities, and the first comprehensive portfolio of NESDIS satellites, instruments, servers, applications, products, user organizations, and user contacts. Select examples of CRM data exploitation will show how OSPO is utilizing the CRM database to more closely satisfy the user community's satellite data needs with new product promotions, as well as new data and imagery distribution methods in OSPO's Environmental Satellite Processing Center (ESPC). In addition, user services and outreach initiatives from the Satellite Products and Services Division will be highlighted.

Division of Integrity and Materials

International Nuclear Information System (INIS)

Zdarek, J.

1995-01-01

The organization structure is described of the Division of Integrity and Materials, Institute of Nuclear Research plc, Rez, and the main fields of their activities given. Listed are the major research projects of the Division in 1994. (Z.S.)

2016 T Division Lightning Talks

Energy Technology Data Exchange (ETDEWEB)

Ramsey, Marilyn Leann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Adams, Luke Clyde [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Ferre, Gregoire Robing [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Grantcharov, Vesselin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Iaroshenko, Oleksandr [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Krishnapriyan, Aditi [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Kurtakoti, Prajvala Kishore [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Le Thien, Minh Quan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Lim, Jonathan Ng [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Low, Thaddeus Song En [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Lystrom, Levi Aaron [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Ma, Xiaoyu [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Nguyen, Hong T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Pogue, Sabine Silvia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Orandle, Zoe Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Reisner, Andrew Ray [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Revard, Benjamin Charles [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Roy, Julien [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Sandor, Csanad [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Slavkova, Kalina Polet [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Weichman, Kathleen Joy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Wu, Fei [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Yang, Yang [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division

2016-11-29

These are the slides for all of the 2016 T Division lightning talks. There are 350 pages worth of slides from different presentations, all of which cover different topics within the theoretical division at Los Alamos National Laboratory (LANL).

Data access performance through parallelization and vectored access. Some results

International Nuclear Information System (INIS)

Furano, F; Hanushevsky, A

2008-01-01

High Energy Physics data processing and analysis applications typically deal with the problem of accessing and processing data at high speed. Recent studies, development and test work have shown that the latencies due to data access can often be hidden by parallelizing them with the data processing, thus giving the ability to have applications which process remote data with a high level of efficiency. Techniques and algorithms able to reach this result have been implemented in the client side of the Scalla/xrootd system, and in this contribution we describe the results of some tests done in order to compare their performance and characteristics. These techniques, if used together with multiple streams data access, can also be effective in allowing to efficiently and transparently deal with data repositories accessible via a Wide Area Network

Analytical Chemistry Division's sample transaction system

International Nuclear Information System (INIS)

Stanton, J.S.; Tilson, P.A.

1980-10-01

The Analytical Chemistry Division uses the DECsystem-10 computer for a wide range of tasks: sample management, timekeeping, quality assurance, and data calculation. This document describes the features and operating characteristics of many of the computer programs used by the Division. The descriptions are divided into chapters which cover all of the information about one aspect of the Analytical Chemistry Division's computer processing

Cognitive-behavioral therapy for obsessive–compulsive disorder: access to treatment, prediction of long-term outcome with neuroimaging

Directory of Open Access Journals (Sweden)

O’Neill J

2015-07-01

Full Text Available Joseph O'Neill,1 Jamie D Feusner,2 1Division of Child Psychiatry, 2Division of Adult Psychiatry, UCLA Semel Institute for Neuroscience and Human Behavior, Los Angeles, CA, USA Abstract: This article reviews issues related to a major challenge to the field for obsessive–compulsive disorder (OCD: improving access to cognitive-behavioral therapy (CBT. Patient-related barriers to access include the stigma of OCD and reluctance to take on the demands of CBT. Patient-external factors include the shortage of trained CBT therapists and the high costs of CBT. The second half of the review focuses on one partial, yet plausible aid to improve access – prediction of long-term response to CBT, particularly using neuroimaging methods. Recent pilot data are presented revealing a potential for pretreatment resting-state functional magnetic resonance imaging and magnetic resonance spectroscopy of the brain to forecast OCD symptom severity up to 1 year after completing CBT. Keywords: follow-up, access to treatment, relapse, resting-state fMRI, magnetic resonance spectroscopy

Data Access, Interoperability and Sustainability: Key Challenges for the Evolution of Science Capabilities

Science.gov (United States)

Walton, A. L.

2015-12-01

In 2016, the National Science Foundation (NSF) will support a portfolio of activities and investments focused upon challenges in data access, interoperability, and sustainability. These topics are fundamental to science questions of increasing complexity that require multidisciplinary approaches and expertise. Progress has become tractable because of (and sometimes complicated by) unprecedented growth in data (both simulations and observations) and rapid advances in technology (such as instrumentation in all aspects of the discovery process, together with ubiquitous cyberinfrastructure to connect, compute, visualize, store, and discover). The goal is an evolution of capabilities for the research community based on these investments, scientific priorities, technology advances, and policies. Examples from multiple NSF directorates, including investments by the Advanced Cyberinfrastructure Division, are aimed at these challenges and can provide the geosciences research community with models and opportunities for participation. Implications for the future are highlighted, along with the importance of continued community engagement on key issues.

Coherence Multiplex System Topologies

NARCIS (Netherlands)

Meijerink, Arjan; Taniman, R.O.; Heideman, G.H.L.M.; van Etten, Wim

2007-01-01

Coherence multiplexing is a potentially inexpensive form of optical code-division multiple access, which is particularly suitable for short-range applications with moderate bandwidth requirements, such as access networks, LANs, or interconnects. Various topologies are known for constructing an

Accessing Wind Tunnels From NASA's Information Power Grid

Science.gov (United States)

Becker, Jeff; Biegel, Bryan (Technical Monitor)

2002-01-01

The NASA Ames wind tunnel customers are one of the first users of the Information Power Grid (IPG) storage system at the NASA Advanced Supercomputing Division. We wanted to be able to store their data on the IPG so that it could be accessed remotely in a secure but timely fashion. In addition, incorporation into the IPG allows future use of grid computational resources, e.g., for post-processing of data, or to do side-by-side CFD validation. In this paper, we describe the integration of grid data access mechanisms with the existing DARWIN web-based system that is used to access wind tunnel test data. We also show that the combined system has reasonable performance: wind tunnel data may be retrieved at 50Mbits/s over a 100 base T network connected to the IPG storage server.

Distributed MIMO chaotic radar based on wavelength-division multiplexing technology.

Science.gov (United States)

Yao, Tingfeng; Zhu, Dan; Ben, De; Pan, Shilong

2015-04-15

A distributed multiple-input multiple-output chaotic radar based on wavelength-division multiplexing technology (WDM) is proposed and demonstrated. The wideband quasi-orthogonal chaotic signals generated by different optoelectronic oscillators (OEOs) are emitted by separated antennas to gain spatial diversity against the fluctuation of a target's radar cross section and enhance the detection capability. The received signals collected by the receive antennas and the reference signals from the OEOs are delivered to the central station for joint processing by exploiting WDM technology. The centralized signal processing avoids precise time synchronization of the distributed system and greatly simplifies the remote units, which improves the localization accuracy of the entire system. A proof-of-concept experiment for two-dimensional localization of a metal target is demonstrated. The maximum position error is less than 6.5 cm.

A hybrid MAC protocol design for energy-efficient very-high-throughput millimeter wave, wireless sensor communication networks

Science.gov (United States)

Jian, Wei; Estevez, Claudio; Chowdhury, Arshad; Jia, Zhensheng; Wang, Jianxin; Yu, Jianguo; Chang, Gee-Kung

2010-12-01

This paper presents an energy-efficient Medium Access Control (MAC) protocol for very-high-throughput millimeter-wave (mm-wave) wireless sensor communication networks (VHT-MSCNs) based on hybrid multiple access techniques of frequency division multiplexing access (FDMA) and time division multiplexing access (TDMA). An energy-efficient Superframe for wireless sensor communication network employing directional mm-wave wireless access technologies is proposed for systems that require very high throughput, such as high definition video signals, for sensing, processing, transmitting, and actuating functions. Energy consumption modeling for each network element and comparisons among various multi-access technologies in term of power and MAC layer operations are investigated for evaluating the energy-efficient improvement of proposed MAC protocol.

Chemical Technology Division annual technical report 1997

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-06-01

The Chemical Technology (CMT) Division is a diverse technical organization with principal emphases in environmental management and development of advanced energy sources. The Division conducts research and development in three general areas: (1) development of advanced power sources for stationary and transportation applications and for consumer electronics, (2) management of high-level and low-level nuclear wastes and hazardous wastes, and (3) electrometallurgical treatment of spent nuclear fuel. The Division also performs basic research in catalytic chemistry involving molecular energy resources, mechanisms of ion transport in lithium battery electrolytes, and the chemistry of technology-relevant materials and electrified interfaces. In addition, the Division operates the Analytical Chemistry Laboratory, which conducts research in analytical chemistry and provides analytical services for programs at Argonne National Laboratory (ANL) and other organizations. Technical highlights of the Division`s activities during 1997 are presented.

Remote access to mathematical software

International Nuclear Information System (INIS)

Dolan, E.; Hovland, P.; More, J.; Norris, B.; Smith, B.

2001-01-01

The network-oriented application services paradigm is becoming increasingly common for scientific computing. The popularity of this approach can be attributed to the numerous advantages to both user and developer provided by network-enabled mathematical software. The burden of installing and maintaining complex systems is lifted from the user, while enabling developers to provide frequent updates without disrupting service. Access to software with similar functionality can be unified under the same interface. Remote servers can utilize potentially more powerful computing resources than may be available locally. We discuss some of the application services developed by the Mathematics and Computer Science Division at Argonne National Laboratory, including the Network Enabled Optimization System (NEOS) Server and the Automatic Differentiation of C (ADIC) Server, as well as preliminary work on Web access to the Portable Extensible Toolkit for Scientific Computing (PETSc). We also provide a brief survey of related work

Lightning Talks 2015: Theoretical Division

Energy Technology Data Exchange (ETDEWEB)

Shlachter, Jack S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-11-25

This document is a compilation of slides from a number of student presentations given to LANL Theoretical Division members. The subjects cover the range of activities of the Division, including plasma physics, environmental issues, materials research, bacterial resistance to antibiotics, and computational methods.

Developmental control of cell division

NARCIS (Netherlands)

Boxem, M. (Mike)

2002-01-01

During development of multicellular organisms, cell divisions need to be coordinated with the developmental program of the entire organism. Although the mechanisms that drive cells through the division cycle are well understood, very little is known about the pathways that link extracellular signals

MPTCP Tunnel: An Architecture for Aggregating Bandwidth of Heterogeneous Access Networks

Directory of Open Access Journals (Sweden)

Xiaolan Liu

2018-01-01

Full Text Available Fixed and cellular networks are two typical access networks provided by operators. Fixed access network is widely employed; nevertheless, its bandwidth is sometimes not sufficient enough to meet user bandwidth requirements. Meanwhile, cellular access network owns unique advantages of wider coverage, faster increasing link speed, more flexible deployment, and so forth. Therefore, it is attractive for operators to mitigate the bandwidth shortage by bundling these two. Actually, there have been existing schemes proposed to aggregate the bandwidth of two access networks, whereas they all have their own problems, like packet reordering or extra latency overhead. To address this problem, we design new architecture, MPTCP Tunnel, to aggregate the bandwidth of multiple heterogeneous access networks from the perspective of operators. MPTCP Tunnel uses MPTCP, which solves the reordering problem essentially, to bundle multiple access networks. Besides, MPTCP Tunnel sets up only one MPTCP connection at play which adapts itself to multiple traffic types and TCP flows. Furthermore, MPTCP Tunnel forwards intact IP packets through access networks, maintaining the end-to-end TCP semantics. Experimental results manifest that MPTCP Tunnel can efficiently aggregate the bandwidth of multiple access networks and is more adaptable to the increasing heterogeneity of access networks than existing mechanisms.

The spatial division of talent in city regions 

DEFF Research Database (Denmark)

Kalsø Hansen, Høgni; Winther, Lars

2010-01-01

The paper focuses on the location dynamics and spatial distribution of talent by workplace to provide evidence of the multiplicity of economic geographies of city regions. City regions are not just homogenous growth machines but complex urban landscapes. The economic growth and revitalisation...... as an important location factor, including the recent focus on the creative class and human capital. Based on an analysis of Copenhagen, we examine the spatial division of talent within industries to provide evidence that new uneven economic geographies of city regions are currently being produced as a result...... of the new location dynamics of the knowledge economy. Further, it is argued that the intraregional division of talent differs considerably even within knowledge intensive industries....

Division of household tasks and financial management

NARCIS (Netherlands)

Antonides, G.

2011-01-01

Both the standard economic model and bargaining theory make predictions about financial management and the division of household labor between household partners. Using a large Internet survey, we have tested several predictions about task divisions reported by Dutch household partners. The division

Development of authentication code for multi-access optical code division multiplexing based quantum key distribution

Science.gov (United States)

Taiwo, Ambali; Alnassar, Ghusoon; Bakar, M. H. Abu; Khir, M. F. Abdul; Mahdi, Mohd Adzir; Mokhtar, M.

2018-05-01

One-weight authentication code for multi-user quantum key distribution (QKD) is proposed. The code is developed for Optical Code Division Multiplexing (OCDMA) based QKD network. A unique address assigned to individual user, coupled with degrading probability of predicting the source of the qubit transmitted in the channel offer excellent secure mechanism against any form of channel attack on OCDMA based QKD network. Flexibility in design as well as ease of modifying the number of users are equally exceptional quality presented by the code in contrast to Optical Orthogonal Code (OOC) earlier implemented for the same purpose. The code was successfully applied to eight simultaneous users at effective key rate of 32 bps over 27 km transmission distance.

E-Division activities report

International Nuclear Information System (INIS)

Barschall, H.H.

1981-07-01

This report describes some of the activities in E (Experimental Physics) Division during the past year. E-Division carries out research and development in areas related to the missions of the Laboratory. Many of the activities are in pure and applied atomic and nuclear physics and in material science. In addition this report describes work on accelerators, microwaves, plasma diagnostics, determination of atmospheric oxygen and of nitrogen in tissue

Chemical Sciences Division: Annual report 1992

International Nuclear Information System (INIS)

1993-10-01

The Chemical Sciences Division (CSD) is one of twelve research Divisions of the Lawrence Berkeley Laboratory, a Department of Energy National Laboratory. The CSD is composed of individual groups and research programs that are organized into five scientific areas: Chemical Physics, Inorganic/Organometallic Chemistry, Actinide Chemistry, Atomic Physics, and Physical Chemistry. This report describes progress by the CSD for 1992. Also included are remarks by the Division Director, a description of work for others (United States Office of Naval Research), and appendices of the Division personnel and an index of investigators. Research reports are grouped as Fundamental Interactions (Photochemical and Radiation Sciences, Chemical Physics, Atomic Physics) or Processes and Techniques (Chemical Energy, Heavy-Element Chemistry, and Chemical Engineering Sciences)

S-band multiple-access interference study for advanced tracking and data relay satellite systems

Science.gov (United States)

Peng, Wei-Chung; Yang, Chau-Chin

1990-01-01

The results of a study on the effect of mutual interference among S-band multiple access (SMA) system users of advanced tracking and data relay satellite system (ATDRSS) are presented. In the ATDRSS era, the SMA system is required to support data rates ranging from 10 kb/s to 3 Mb/s. The system will consist of four advanced tracking and data relay satellites (ATDRS) each supporting up to five telemetry links. All users have 10 MHz bandwidth with their carrier frequency equal to 2.2875 GHz. A hybrid SDMA/CDMA scheme is used to mitigate the effect of the interference among system users. SMA system interference probability is evaluated with CLASS software. User link margin degradation due to mutual interference between two users is evaluated. System interference probability is evaluated for the projected 1996 mission model, a reference mission model, and a modified reference mission model.

Improving Access to European E-theses: the DART-Europe Programme

Directory of Open Access Journals (Sweden)

Martin Moyle

2008-11-01

Full Text Available DART-Europe (Digital Access to Research Theses - Europe is a partnership of research libraries and library consortia who are working together to improve global access to European research theses. The Programme is endorsed by LIBER (Ligue des Bibliothèques Européennes de Recherche as part of the work of the LIBER Access Division, and it is the European Working Group of the NDLTD (Networked Digital Library of Theses and Dissertations. DART-Europe serves as a European networking forum on issues relating to electronic theses. The DART-Europe partners share an enthusiasm for open access to research theses, and they have helped to provide researchers with the DART-Europe E-theses Portal, a service which enables the discovery of the open access research-level e-theses offered by institutions and consortia from a growing number of European countries. This article gives an overview of DART-Europe, its progress and its future plans, with particular reference to the DART-Europe E-theses Portal.

Insights into the Mechanisms of Chloroplast Division

Directory of Open Access Journals (Sweden)

Yamato Yoshida

2018-03-01

Full Text Available The endosymbiosis of a free-living cyanobacterium into an ancestral eukaryote led to the evolution of the chloroplast (plastid more than one billion years ago. Given their independent origins, plastid proliferation is restricted to the binary fission of pre-existing plastids within a cell. In the last 25 years, the structure of the supramolecular machinery regulating plastid division has been discovered, and some of its component proteins identified. More recently, isolated plastid-division machineries have been examined to elucidate their structural and mechanistic details. Furthermore, complex studies have revealed how the plastid-division machinery morphologically transforms during plastid division, and which of its component proteins play a critical role in generating the contractile force. Identifying the three-dimensional structures and putative functional domains of the component proteins has given us hints about the mechanisms driving the machinery. Surprisingly, the mechanisms driving plastid division resemble those of mitochondrial division, indicating that these division machineries likely developed from the same evolutionary origin, providing a key insight into how endosymbiotic organelles were established. These findings have opened new avenues of research into organelle proliferation mechanisms and the evolution of organelles.

Energy Technology Division research summary 2001

International Nuclear Information System (INIS)

2001-01-01

The Energy Technology Division provides materials and engineering technology support to a wide range of programs important to the U.S. Department of Energy. As shown on the preceding page, the Division is organized into eight sections, four with concentrations in the materials area and four in engineering technology. Materials expertise includes fabrication, mechanical properties, corrosion, friction and lubrication, and irradiation effects. Our major engineering strengths are in heat and mass flow, sensors and instrumentation, nondestructive testing, transportation, and electromechanics and superconductivity applications. The Division Safety Coordinator, Environmental Compliance Officer, Quality Assurance Representative, Financial Administrator, and Communication Coordinator report directly to the Division Director. The Division Director is personally responsible for cultural diversity and is a member of the Laboratory-wide Cultural Diversity Advisory Committee. This Overview highlights some major ET research areas. Research related to the operational safety of commercial light water nuclear reactors (LWRs) for the U.S. Nuclear Regulatory Commission (NRC) remains a significant area of interest for the Division. We currently have programs on environmentally assisted cracking, steam generator integrity, and the integrity of high-burnup fuel during loss-of-coolant accidents. The bulk of the NRC research work is carried out by three ET sections: Corrosion and Mechanics of Materials; Irradiation Performance; and Sensors, Instrumentation, and Nondestructive Evaluation

Distributed Access View Integrated Database (DAVID) system

Science.gov (United States)

Jacobs, Barry E.

1991-01-01

The Distributed Access View Integrated Database (DAVID) System, which was adopted by the Astrophysics Division for their Astrophysics Data System, is a solution to the system heterogeneity problem. The heterogeneous components of the Astrophysics problem is outlined. The Library and Library Consortium levels of the DAVID approach are described. The 'books' and 'kits' level is discussed. The Universal Object Typer Management System level is described. The relation of the DAVID project with the Small Business Innovative Research (SBIR) program is explained.

The 1988 Leti Division progress report

International Nuclear Information System (INIS)

Anon.

1988-01-01

The 1988 progress report of the CEA's LETI Division (Division of Electronics, Technology and Instrumentation, France) is presented. The missions of LETI Division involve military and nuclear applications of electronics and fundamental research. The research programs developed in 1988 are the following: materials and components, non-volatile silicon memories, silicon-over-insulator, integrated circuits technologies, common experimental laboratory (opened to the European community), mass memories, photodetectors, micron sensors and flat screens [fr

Energy Technology Division research summary - 1999.

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-03-31

The Energy Technology Division provides materials and engineering technology support to a wide range of programs important to the US Department of Energy. As shown on the preceding page, the Division is organized into ten sections, five with concentrations in the materials area and five in engineering technology. Materials expertise includes fabrication, mechanical properties, corrosion, friction and lubrication, and irradiation effects. Our major engineering strengths are in heat and mass flow, sensors and instrumentation, nondestructive testing, transportation, and electromechanics and superconductivity applications. The Division Safety Coordinator, Environmental Compliance Officers, Quality Assurance Representative, Financial Administrator, and Communication Coordinator report directly to the Division Director. The Division Director is personally responsible for cultural diversity and is a member of the Laboratory-wide Cultural Diversity Advisory Committee. The Division's capabilities are generally applied to issues associated with energy production, transportation, utilization, or conservation, or with environmental issues linked to energy. As shown in the organization chart on the next page, the Division reports administratively to the Associate Laboratory Director (ALD) for Energy and Environmental Science and Technology (EEST) through the General Manager for Environmental and Industrial Technologies. While most of our programs are under the purview of the EEST ALD, we also have had programs funded under every one of the ALDs. Some of our research in superconductivity is funded through the Physical Research Program ALD. We also continue to work on a number of nuclear-energy-related programs under the ALD for Engineering Research. Detailed descriptions of our programs on a section-by-section basis are provided in the remainder of this book.

On Secure Two-Party Integer Division

DEFF Research Database (Denmark)

Dahl, Morten; Ning, Chao; Toft, Tomas

2012-01-01

{\\mathcal{O}}(\\ell)$ arithmetic operations on encrypted values (secure addition and multiplication) in $\\ensuremath{\\mathcal{O}}(1)$ rounds. This is the most efficient constant-rounds solution to date. The second protocol requires only $\\ensuremath{\\mathcal{O}} \\left( (\\log^2 \\ell)(\\kappa + \\operatorname{loglog} \\ell) \\right......We consider the problem of secure integer division: given two Paillier encryptions of ℓ-bit values n and d, determine an encryption of $\\lfloor \\frac{n}{d}\\rfloor$ without leaking any information about n or d. We propose two new protocols solving this problem. The first requires $\\ensuremath......)$ arithmetic operations in $\\ensuremath{\\mathcal{O}}(\\log^2 \\ell)$ rounds, where κ is a correctness parameter. Theoretically, this is the most efficient solution to date as all previous solutions have required Ω(ℓ) operations. Indeed, the fact that an o(ℓ) solution is possible at all is highly surprising....

Centralized optical-frequency-comb-based RF carrier generator for DWDM fiber-wireless access systems

DEFF Research Database (Denmark)

Pang, Xiaodan; Beltran, Marta; Sanchez, Jose

2014-01-01

In this paper, we report on a gigabit capacity fiber-wireless system that enables smooth integration between high-speed wireless networks and dense wavelength-division-multiplexing (DWDM) access networks. By employing a centralized optical frequency comb, both the wireline and the wireless services...

Multiple Off-Ice Performance Variables Predict On-Ice Skating Performance in Male and Female Division III Ice Hockey Players.

Science.gov (United States)

Janot, Jeffrey M; Beltz, Nicholas M; Dalleck, Lance D

2015-09-01

The purpose of this study was to determine if off-ice performance variables could predict on-ice skating performance in Division III collegiate hockey players. Both men (n = 15) and women (n = 11) hockey players (age = 20.5 ± 1.4 years) participated in the study. The skating tests were agility cornering S-turn, 6.10 m acceleration, 44.80 m speed, modified repeat skate, and 15.20 m full speed. Off-ice variables assessed were years of playing experience, height, weight and percent body fat and off-ice performance variables included vertical jump (VJ), 40-yd dash (36.58m), 1-RM squat, pro-agility, Wingate peak power and peak power percentage drop (% drop), and 1.5 mile (2.4km) run. Results indicated that 40-yd dash (36.58m), VJ, 1.5 mile (2.4km) run, and % drop were significant predictors of skating performance for repeat skate (slowest, fastest, and average time) and 44.80 m speed time, respectively. Four predictive equations were derived from multiple regression analyses: 1) slowest repeat skate time = 2.362 + (1.68 x 40-yd dash time) + (0.005 x 1.5 mile run), 2) fastest repeat skate time = 9.762 - (0.089 x VJ) - (0.998 x 40-yd dash time), 3) average repeat skate time = 7.770 + (1.041 x 40-yd dash time) - (0.63 x VJ) + (0.003 x 1.5 mile time), and 4) 47.85 m speed test = 7.707 - (0.050 x VJ) - (0.01 x % drop). It was concluded that selected off-ice tests could be used to predict on-ice performance regarding speed and recovery ability in Division III male and female hockey players. Key pointsThe 40-yd dash (36.58m) and vertical jump tests are significant predictors of on-ice skating performance specific to speed.In addition to 40-yd dash and vertical jump, the 1.5 mile (2.4km) run for time and percent power drop from the Wingate anaerobic power test were also significant predictors of skating performance that incorporates the aspect of recovery from skating activity.Due to the specificity of selected off-ice variables as predictors of on-ice performance, coaches can

Physics division annual report 2006.

Energy Technology Data Exchange (ETDEWEB)

Glover, J.; Physics

2008-02-28

This report highlights the activities of the Physics Division of Argonne National Laboratory in 2006. The Division's programs include the operation as a national user facility of ATLAS, the Argonne Tandem Linear Accelerator System, research in nuclear structure and reactions, nuclear astrophysics, nuclear theory, investigations in medium-energy nuclear physics as well as research and development in accelerator technology. The mission of nuclear physics is to understand the origin, evolution and structure of baryonic matter in the universe--the core of matter, the fuel of stars, and the basic constituent of life itself. The Division's research focuses on innovative new ways to address this mission.

Random transmission scheme approach for a FMCW TDMA coherent MIMO radar

NARCIS (Netherlands)

Belfiori, F.; Rossum, W.L. van; Hoogeboom, P.

2012-01-01

In this paper the authors analyze the use of Time Division Multiple Access (TDMA) applied to coherent Multiple-Input Multiple-Output (MIMO) radar systems. One of the main limitations in exploiting the orthogonal condition in the time domain for MIMO radars is the reduction of the unambiguous Doppler

Division of Analytical Chemistry, 1998

DEFF Research Database (Denmark)

Hansen, Elo Harald

1999-01-01

The article recounts the 1998 activities of the Division of Analytical Chemistry (DAC- formerly the Working Party on Analytical Chemistry, WPAC), which body is a division of the Federation of European Chemical Societies (FECS). Elo Harald Hansen is the Danish delegate, representing The Danish...... Chemical Society/The Society for Analytical Chemistry....

Current programmes of Metallurgy Division (1991)

International Nuclear Information System (INIS)

1991-01-01

Current research and development programmes of the Metallurgy Division are listed under the headings: 1)Thrust Areas, 2)High Temperature Materials Section, 3)Chemical Metallurgy Section, 4)Metallurgical Thermochemistry Section, 5)Physical Metallurgy Section, 6)Mechanical Metallurgy Section, 7)Corrosion Metallurgy Section, 8)Electrochemical Science and Technology Section, 9)Ceramics Section, and 10)Fabrication and Maintenance Group. A list of equipment in the Division and a list of sciientific personnel of the Division are also given. (M.G.B.)

Interferometric characterization of few-mode fibers (FMF) for mode-division multiplexing (MDM)

OpenAIRE

Muliar, Olena; Usuga Castaneda, Mario A.; Rottwitt, Karsten; Lægsgaard, Jesper

2015-01-01

The rapid growth of global data traffic demands the continuous search for new technologies and systems that could increase transmission capacity in optical links and recent experiments show that to do so, it is advantageous to explore new degrees of freedom such as polarization, wavelength or optical modes. Mode division multiplexing (MDM) appears in this context as a promising and viable solution for such capacity increase, since it utilizes multiple spatial modes of an optical fiber as indi...

STAR-TYPE LOCAL AREA NETWORK ACCESS CONTROL

Institute of Scientific and Technical Information of China (English)

逯昭义; 齐藤忠夫

1990-01-01

The multiple access fashion is a new resolution for the star-type local area network (LAN) access control and star-type optical fibre LAN. Arguments about this network are discussed, and the results are introduced.

An Alternative Route to Teaching Fraction Division: Abstraction of Common Denominator Algorithm

Directory of Open Access Journals (Sweden)

İsmail Özgür ZEMBAT

2015-06-01

Full Text Available From a curricular stand point, the traditional invert and multiply algorithm for division of fractions provides few affordances for linking to a rich understanding of fractions. On the other hand, an alternative algorithm, called common denominator algorithm, has many such affordances. The current study serves as an argument for shifting curriculum for fraction division from use of invert and multiply algorithm as a basis to the use of common denominator algorithm as a basis. This was accomplished with the analysis of learning of two prospective elementary teachers being an illustration of how to realize those conceptual affordances. In doing so, the article proposes an instructional sequence and details it by referring to both the (mathematical and pedagogical advantages and the disadvantages. As a result, this algorithm has a conceptual basis depending on basic operations of partitioning, unitizing, and counting, which make it accessible to learners. Also, when participants are encouraged to construct this algorithm based on their work with diagrams, common denominator algorithm formalizes the work that they do with diagrams.

An alternative route to teaching fraction division: Abstraction of common denominator algorithm

Directory of Open Access Journals (Sweden)

İsmail Özgür Zembat

2015-07-01

Full Text Available From a curricular stand point, the traditional invert and multiply algorithm for division of fractions provides few affordances for linking to a rich understanding of fractions. On the other hand, an alternative algorithm, called common denominator algorithm, has many such affordances. The current study serves as an argument for shifting curriculum for fraction division from use of invert and multiply algorithm as a basis to the use of common denominator algorithm as a basis. This was accomplished with the analysis of learning of two prospective elementary teachers being an illustration of how to realize those conceptual affordances. In doing so, the article proposes an instructional sequence and details it by referring to both the (mathematical and pedagogical advantages and the disadvantages. As a result, this algorithm has a conceptual basis depending on basic operations of partitioning, unitizing, and counting, which make it accessible to learners. Also, when participants are encouraged to construct this algorithm based on their work with diagrams, common denominator algorithm formalizes the work that they do with diagrams.

Chemical and Laser Sciences Division annual report 1989

International Nuclear Information System (INIS)

Haines, N.

1990-06-01

The Chemical and Laser Sciences Division Annual Report includes articles describing representative research and development activities within the Division, as well as major programs to which the Division makes significant contributions

Correlator receiver architecture with PnpN optical thyristor operating as optical hard-limiter

Science.gov (United States)

Kang, Tae-Gu; Ho Lee, Su; Park, Soonchul

2011-07-01

We propose novel correlator receiver architecture with a PnpN optical thyristor operating as optical hard-limiter, and demonstrate a multiple-access interference rejection of the proposed correlator receiver. The proposed correlator receiver is composed of the 1×2 splitter, optical delay line, 2×1 combiner, and fabricated PnpN optical thyristor. The proposed correlator receiver enhances the system performance because it excludes some combinations of multiple-access interference patterns from causing errors as in optical code-division multiple access systems with conventional optical receiver shown in all previous works. It is found that the proposed correlator receiver can fully reject the interference signals generated by decoding processing and multiple access for two simultaneous users.

Six to Ten Digits Multiplication Fun Learning Using Puppet Prototype

Science.gov (United States)

Islamiah Rosli, D.'oria; Ali, Azita; Peng, Lim Soo; Sujardi, Imam; Usodo, Budi; Adie Perdana, Fengky

2017-01-01

Logic and technical subjects require students to understand basic knowledge in mathematic. For instance, addition, minus, division and multiplication operations need to be mastered by students due to mathematic complexity as the learning mathematic grows higher. Weak foundation in mathematic also contribute to high failure rate in mathematic subjects in schools. In fact, students in primary schools are struggling to learn mathematic because they need to memorize formulas, multiplication or division operations. To date, this study will develop a puppet prototyping for learning mathematic for six to ten digits multiplication. Ten participants involved in the process of developing the prototype in this study. Students involved in the study were those from the intermediate class students whilst teachers were selected based on their vast knowledge and experiences and have more than five years of experience in teaching mathematic. Close participatory analysis will be used in the prototyping process as to fulfil the requirements of the students and teachers whom will use the puppet in learning six to ten digit multiplication in mathematic. Findings showed that, the students had a great time and fun learning experience in learning multiplication and they able to understand the concept of multiplication using puppet. Colour and materials of the puppet also help to attract student attention during learning. Additionally, students able to visualized and able to calculate accurate multiplication value and the puppet help them to recall in multiplying and adding the digits accordingly.

Division of Information Technology - Overview

International Nuclear Information System (INIS)

Szlachciak, J.

2007-01-01

I have a great pleasure to introduce the youngest division in our Institute, namely the Division of Information Technology. The division was created in 2005, but this is the first time when it reports its activities. The main purpose of creation was a better management of al IT activities in different departments, lowering IT costs and increase security over all computer systems used be the Institute. Although we have started with small human resources, we have received a big support from other departments. Special thanks go to the Department of Detectors and Nuclear Electronics. Our division handles many service-oriented activities. In daily work we answer many IT-related questions and deliver our help in order to solve hardware and software problems. The style of our work can be described as a result-oriented one. Here is the list of our biggest achievements: · construction of the server room; · implementation of two electronic bank systems; · development of the dynamic hardware and software inventory system; · development of the Scientific Activity Database. (author)

The Border Multiple

DEFF Research Database (Denmark)

Addressing and conceptualizing the changing character of borders in contemporary Europe, this book examines developments occurring in the light of European integration processes and an on-going tightening of Europe's external borders. Moreover, the book suggests new ways of investigating the nature...... of European borders by looking at border practices in the light of the mobility turn, and thus as dynamic, multiple, diverse and best expressed in everyday experiences of people living at and with borders, rather than focusing on static territorial divisions between states and regions at geopolitical level...

An examination of the stretching practices of Division I and Division III college football programs in the midwestern United States.

Science.gov (United States)

Judge, Lawrence W; Craig, Bruce; Baudendistal, Steve; Bodey, Kimberly J

2009-07-01

Research supports the use of preactivity warm-up and stretching, and the purpose of this study was to determine whether college football programs follow these guidelines. Questionnaires designed to gather demographic, professional, and educational information, as well as specific pre- and postactivity practices, were distributed via e-mail to midwestern collegiate programs from NCAA Division I and III conferences. Twenty-three male coaches (12 from Division IA schools and 11 from Division III schools) participated in the study. Division I schools employed certified strength coaches (CSCS; 100%), whereas Division III schools used mainly strength coordinators (73%), with only 25% CSCS. All programs used preactivity warm-up, with the majority employing 2-5 minutes of sport-specific jogging/running drills. Pre stretching (5-10 minutes) was performed in 19 programs (91%), with 2 (9%) performing no pre stretching. Thirteen respondents used a combination of static/proprioceptive neuromuscular facilitation/ballistic and dynamic flexibility, 5 used only dynamic flexibility, and 1 used only static stretching. All 12 Division I coaches used stretching, whereas only 9 of the 11 Division III coaches did (p = 0.22). The results indicate that younger coaches did not use pre stretching (p = 0.30). The majority of the coaches indicated that they did use post stretching, with 11 of the 12 Division I coaches using stretching, whereas only 5 of the 11 Division III coaches used stretching postactivity (p = 0.027). Divisional results show that the majority of Division I coaches use static-style stretching (p = 0.049). The results of this study indicate that divisional status, age, and certification may influence how well research guidelines are followed. Further research is needed to delineate how these factors affect coaching decisions.

Mining Social Tagging Data for Enhanced Subject Access for Readers and Researchers

Science.gov (United States)

Lawson, Karen G.

2009-01-01

Social tagging enables librarians to partner with users to provide enhanced subject access. This paper quantifies and compares LC subject headings from each of 31 different subject divisions with user tags from Amazon.com and LibraryThing assigned to the same titles. The intersection and integration of these schemas is described and evaluated.…

Energy Technology Division research summary 2004

International Nuclear Information System (INIS)

Poeppel, R. B.; Shack, W. J.

2004-01-01

The Energy Technology (ET) Division provides materials and engineering technology support to a wide range of programs important to the US Department of Energy (DOE). The Division's capabilities are generally applied to technical issues associated with energy systems, biomedical engineering, transportation, and homeland security. Research related to the operational safety of commercial light water nuclear reactors (LWRs) for the US Nuclear Regulatory Commission (NRC) remains another significant area of interest for the Division. The pie chart below summarizes the ET sources of funding for FY 2004

1998 Chemical Technology Division Annual Technical Report.

Energy Technology Data Exchange (ETDEWEB)

Ackerman, J.P.; Einziger, R.E.; Gay, E.C.; Green, D.W.; Miller, J.F.

1999-08-06

The Chemical Technology (CMT) Division is a diverse technical organization with principal emphases in environmental management and development of advanced energy sources. The Division conducts research and development in three general areas: (1) development of advanced power sources for stationary and transportation applications and for consumer electronics, (2) management of high-level and low-level nuclear wastes and hazardous wastes, and (3) electrometallurgical treatment of spent nuclear fuel. The Division also performs basic research in catalytic chemistry involving molecular energy resources, mechanisms of ion transport in lithium battery electrolytes, and the chemistry of technology-relevant materials. In addition, the Division operates the Analytical Chemistry Laboratory, which conducts research in analytical chemistry and provides analytical services for programs at Argonne National Laboratory (ANL) and other organizations. Technical highlights of the Division's activities during 1998 are presented.

Chemical Technology Division annual technical report 1997

International Nuclear Information System (INIS)

1998-06-01

The Chemical Technology (CMT) Division is a diverse technical organization with principal emphases in environmental management and development of advanced energy sources. The Division conducts research and development in three general areas: (1) development of advanced power sources for stationary and transportation applications and for consumer electronics, (2) management of high-level and low-level nuclear wastes and hazardous wastes, and (3) electrometallurgical treatment of spent nuclear fuel. The Division also performs basic research in catalytic chemistry involving molecular energy resources, mechanisms of ion transport in lithium battery electrolytes, and the chemistry of technology-relevant materials and electrified interfaces. In addition, the Division operates the Analytical Chemistry Laboratory, which conducts research in analytical chemistry and provides analytical services for programs at Argonne National Laboratory (ANL) and other organizations. Technical highlights of the Division's activities during 1997 are presented

2002 Chemical Engineering Division annual report

International Nuclear Information System (INIS)

Lewis, D.; Graziano, D.; Miller, J. F.

2003-01-01

The Chemical Engineering Division is one of eight engineering research divisions within Argonne National Laboratory, one of the U.S. government's oldest and largest research laboratories. The University of Chicago oversees the laboratory on behalf of the U.S. Department of Energy (DOE). Argonne's mission is to conduct basic scientific research, to operate national scientific facilities, to enhance the nation's energy resources, and to develop better ways to manage environmental problems. Argonne has the further responsibility of strengthening the nation's technology base by developing innovative technology and transferring it to industry. The Division is a diverse early-stage engineering organization, specializing in the treatment of spent nuclear fuel, development of advanced electrochemical power sources, and management of both high- and low-level nuclear wastes. Although this work is often indistinguishable from basic research, our efforts are directed toward the practical devices and processes that are covered by Argonne's mission. Additionally, the Division operates the Analytical Chemistry Laboratory; Environment, Safety, and Health Analytical Chemistry services; and Dosimetry and Radioprotection services, which provide a broad range of analytical services to Argonne and other organizations. The Division is multidisciplinary. Its people have formal training as ceramists; physicists; material scientists; electrical, mechanical, chemical, and nuclear engineers; and chemists. They have experience working in academia; urban planning; and the petroleum, aluminum, and automotive industries. Their skills include catalysis, ceramics, electrochemistry, metallurgy, nuclear magnetic resonance spectroscopy, and petroleum refining, as well as the development of nuclear waste forms, batteries, and high-temperature superconductors. Our wide-ranging expertise finds ready application in solving energy and environmental problems. Division personnel are frequently called on by

Energy Division progress report, fiscal years 1994--1995

Energy Technology Data Exchange (ETDEWEB)

Moser, C.I. [ed.

1996-06-01

At ORNL, the Energy Division`s mission is to provide innovative solutions to energy and related issues of national and global importance through interdisciplinary research and development. Its goals and accomplishments are described in this progress report for FY 1994 and FY 1995. The Division`s expenditures in FY 1995 totaled 44.9 million. Sixty percent of the divisions work was supported by the US DOE. Other significant sponsors include the US DOT, the US DOD, other federal agencies, and some private organizations. The Division`s programmatic activities cover three main areas: (1) analysis and assessment, (2) transportation systems, and (3) energy use and delivery technologies. Analysis and assessment activities involve energy and resource analysis, preparation of environmental assessments and impact statements, and impact statements, research on emergency preparedness, analysis of energy and environmental needs in developing countries, and transportation analysis. Transportation systems research seeks to improve the quality of both civilian and military transportation efforts. Energy use and delivery technologies focus on building equipment, building envelopes, (walls, roofs, attics, and materials), improvement of energy efficiency in buildings, and electric power systems.

Power Dissipation in Division

DEFF Research Database (Denmark)

Liu, Wei; Nannarelli, Alberto

2008-01-01

A few classes of algorithms to implement division in hardware have been used over the years: division by digit-recurrence, by reciprocal approximation by iterative methods and by polynomial approximation. Due to the differences in the algorithms, a comparison among their implementation in terms o...... of performance and precision is sometimes hard to make. In this work, we use power dissipation and energy consumption as metrics to compare among those different classes of algorithms. There are no previous works in the literature presenting such a comparison....

Important projects of the Division

International Nuclear Information System (INIS)

2008-01-01

In this chapter important projects of the Division for Radiation Safety, NPP Decommissioning and Radwaste Management of the VUJE, a. s. are presented. Division for Radiation Safety, NPP Decommissioning and Radwaste Management has successfully carried out variety of significant projects. The most significant projects that were realised, are implemented and possible future projects are introduced in the following part of presentation.

A Novel Power-Saving Transmission Scheme for Multiple-Component-Carrier Cellular Systems

Directory of Open Access Journals (Sweden)

Yao-Liang Chung

2016-04-01

Full Text Available As mobile data traffic levels have increased exponentially, resulting in rising energy costs in recent years, the demand for and development of green communication technologies has resulted in various energy-saving designs for cellular systems. At the same time, recent technological advances have allowed multiple component carriers (CCs to be simultaneously utilized in a base station (BS, a development that has made the energy consumption of BSs a matter of increasing concern. To help address this concern, herein we propose a novel scheme aimed at efficiently minimizing the power consumption of BS transceivers during transmission, while still ensuring good service quality and fairness for users. Specifically, the scheme utilizes the dynamic activation/deactivation of CCs during data transmission to increase power usage efficiency. To test its effectiveness, the proposed scheme was applied to a model consisting of a BS with orthogonal frequency division multiple access-based CCs in a downlink transmission environment. The results indicated that, given periods of relatively light traffic loads, the total power consumption of the proposed scheme is significantly lower than that of schemes in which all the CCs of a BS are constantly activated, suggesting the scheme’s potential for reducing both energy costs and carbon dioxide emissions.

Improved Encrypted-Signals-Based Reversible Data Hiding Using Code Division Multiplexing and Value Expansion

Directory of Open Access Journals (Sweden)

Xianyi Chen

2018-01-01

Full Text Available Compared to the encrypted-image-based reversible data hiding (EIRDH method, the encrypted-signals-based reversible data hiding (ESRDH technique is a novel way to achieve a greater embedding rate and better quality of the decrypted signals. Motivated by ESRDH using signal energy transfer, we propose an improved ESRDH method using code division multiplexing and value expansion. At the beginning, each pixel of the original image is divided into several parts containing a little signal and multiple equal signals. Next, all signals are encrypted by Paillier encryption. And then a large number of secret bits are embedded into the encrypted signals using code division multiplexing and value expansion. Since the sum of elements in any spreading sequence is equal to 0, lossless quality of directly decrypted signals can be achieved using code division multiplexing on the encrypted equal signals. Although the visual quality is reduced, high-capacity data hiding can be accomplished by conducting value expansion on the encrypted little signal. The experimental results show that our method is better than other methods in terms of the embedding rate and average PSNR.

Experimental demonstration of SCMA-OFDM for passive optical network

Science.gov (United States)

Lin, Bangjiang; Tang, Xuan; Shen, Xiaohuan; Zhang, Min; Lin, Chun; Ghassemlooy, Zabih

2017-12-01

We introduces a novel architecture for next generation passive optical network (PON) based on the employment of sparse code multiple access (SCMA) combined with orthogonal frequency division multiplexing (OFDM) modulation, in which the binary data is directly encoded to multi-dimensional codewords and then spread over OFDM subcarriers. The feasibility of SCMA-OFDM-PON is verified with experimental demonstration. We show that the SCMA-OFDM offers 150% overloading gain in the number of optical network units compared with the orthogonal frequency division multiplexing access.

Stationary infinitely divisible processes

DEFF Research Database (Denmark)

Barndorff-Nielsen, Ole E.

Several recent strands of work has led to the consideration of various types of continuous time stationary and infinitely divisible processes. A review of these types, with some new results, is presented.......Several recent strands of work has led to the consideration of various types of continuous time stationary and infinitely divisible processes. A review of these types, with some new results, is presented....

FtsZ-less prokaryotic cell division as well as FtsZ- and dynamin-less chloroplast and non-photosynthetic plastid division

Directory of Open Access Journals (Sweden)

Shin-Ya eMiyagishima

2014-09-01

Full Text Available The chloroplast division machinery is a mixture of a stromal FtsZ-based complex descended from a cyanobacterial ancestor of chloroplasts and a cytosolic dynamin-related protein (DRP 5B-based complex derived from the eukaryotic host. Molecular genetic studies have shown that each component of the division machinery is normally essential for normal chloroplast division. However, several exceptions have been found. In the absence of the FtsZ ring, nonphotosynthetic plastids are able to proliferate, likely by elongation and budding. Depletion of DRP5B impairs, but does not stop chloroplast division. Chloroplasts in glaucophytes, which possesses a peptidoglycan (PG layer, divide without DRP5B. Certain parasitic eukaryotes possess nonphotosynthetic plastids of secondary endosymbiotic origin, but neither FtsZ nor DRP5B is encoded in their genomes. Elucidation of the FtsZ- and/or DRP5B-less chloroplast division mechanism will lead to a better understanding of the function and evolution of the chloroplast division machinery and the finding of the as-yet-unknown mechanism that is likely involved in chloroplast division. Recent studies have shown that FtsZ was lost from a variety of prokaryotes, many of which lost PG by regressive evolution. In addition, even some of the FtsZ-bearing bacteria are able to divide when FtsZ and PG are depleted experimentally. In some cases, alternative mechanisms for cell division, such as budding by an increase of the cell surface-to-volume ratio, are proposed. Although PG is believed to have been lost from chloroplasts other than in glaucophytes, there is some indirect evidence for the existence of PG in chloroplasts. Such information is also useful for understanding how nonphotosynthetic plastids are able to divide in FtsZ-depleted cells and the reason for the retention of FtsZ in chloroplast division. Here we summarize information to facilitate analyses of FtsZ- and/or DRP5B-less chloroplast and nonphotosynthetic plastid

System and method for integrating and accessing multiple data sources within a data warehouse architecture

Science.gov (United States)

Musick, Charles R [Castro Valley, CA; Critchlow, Terence [Livermore, CA; Ganesh, Madhaven [San Jose, CA; Slezak, Tom [Livermore, CA; Fidelis, Krzysztof [Brentwood, CA

2006-12-19

A system and method is disclosed for integrating and accessing multiple data sources within a data warehouse architecture. The metadata formed by the present method provide a way to declaratively present domain specific knowledge, obtained by analyzing data sources, in a consistent and useable way. Four types of information are represented by the metadata: abstract concepts, databases, transformations and mappings. A mediator generator automatically generates data management computer code based on the metadata. The resulting code defines a translation library and a mediator class. The translation library provides a data representation for domain specific knowledge represented in a data warehouse, including "get" and "set" methods for attributes that call transformation methods and derive a value of an attribute if it is missing. The mediator class defines methods that take "distinguished" high-level objects as input and traverse their data structures and enter information into the data warehouse.

Earth Sciences Division collected abstracts: 1979

International Nuclear Information System (INIS)

Henry, A.L.; Schwartz, L.L.

1980-01-01

This report is a compilation of abstracts of papers, internal reports, and talks presented during 1979 at national and international meetings by members of the Earth Sciences Division, Lawrence Livermore Laboratory. The arrangement is alphabetical (by author). For a given report, a bibliographic reference appears under the name of each coauthor, but the abstract iself is given only under the name of the first author or the first Earth Sciences Division author. A topical index at the end of the report provides useful cross references, while indicating major areas of research interest in the Earth Sciences Division

Chemical Sciences Division annual report 1994

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-06-01

The division is one of ten LBL research divisions. It is composed of individual research groups organized into 5 scientific areas: chemical physics, inorganic/organometallic chemistry, actinide chemistry, atomic physics, and chemical engineering. Studies include structure and reactivity of critical reaction intermediates, transients and dynamics of elementary chemical reactions, and heterogeneous and homogeneous catalysis. Work for others included studies of superconducting properties of high-{Tc} oxides. In FY 1994, the division neared completion of two end-stations and a beamline for the Advanced Light Source, which will be used for combustion and other studies. This document presents summaries of the studies.

All-Optical Regeneration System for Optical Wavelength Division Multiplexed Communication Systems

DEFF Research Database (Denmark)

2014-01-01

The invention relates to an all-optical regeneration system for regeneration of optical wavelength division multiplexed WDM data signals in an optical WDM communication system. The system comprises a WDM-to-Optical time domain multiplexing OTDM, WDM-to-OTDM, converter, capable of converting....... The system additionally comprises an OTDM-to-WDM converter for converting the output OTDM data signal to an output WDM data signal. An input of the all-optical regenerator unit is in optical communication with an output of the WDM-to-OTDM converter, and an output of the all-optical regenerator unit...... an input WDM data signal comprising multiple wavelength channels into an input OTDM data signal comprising multiple time multiplexed time channels. The system further comprises an all-optical regenerator unit being configured for regenerating the input OTDM data signal into an output OTDM data signal...

Non-Orthogonal Multiple Access for Large-Scale 5G Networks: Interference Aware Design

KAUST Repository

Ali, Konpal S.

2017-09-18

Non-orthogonal multiple access (NOMA) is promoted as a key component of 5G cellular networks. As the name implies, NOMA operation introduces intracell interference (i.e., interference arising within the cell) to the cellular operation. The intracell interference is managed by careful NOMA design (e.g., user clustering and resource allocation) along with successive interference cancellation. However, most of the proposed NOMA designs are agnostic to intercell interference (i.e., interference from outside the cell), which is a major performance limiting parameter in 5G networks. This article sheds light on the drastic negative-impact of intercell interference on the NOMA performance and advocates interference-aware NOMA design that jointly accounts for both intracell and intercell interference. To this end, a case study for fair NOMA operation is presented and intercell interference mitigation techniques for NOMA networks are discussed. This article also investigates the potential of integrating NOMA with two important 5G transmission schemes, namely, full duplex and device-to-device communication. This is important since the ambitious performance defined by the 3rd Generation Partnership Project (3GPP) for 5G is foreseen to be realized via seamless integration of several new technologies and transmission techniques.

Theoretical Division annual report, FY 1975

International Nuclear Information System (INIS)

Carruthers, P.A.

1976-02-01

This report presents an overview of the activities in the Theoretical Division and a summary of research highlights during FY 1975. It is intended to inform a wide audience about the theoretical work of the LASL and, therefore, contains introductory material which places recent advances in a broader context. The report is organized into two special interest reports: reactor safety research and the Advanced Research Committee, and 11 reports from the T-Division group leaders on the work of their respective groups. Main interests and responsibilities are outlined including the relationship of the group's work to the work of other T-Division groups and other divisions at the Laboratory. The description of research highlights for FY 1975 explains in a fairly simple, straightforward manner the major recent advances and their significance. Each group report is followed by a publication list for FY 1975 (330 references) and a list of talks given outside the Laboratory (140 references). 29 figures

The History of Metals and Ceramics Division

Energy Technology Data Exchange (ETDEWEB)

Craig, D.F.

1999-01-01

The division was formed in 1946 at the suggestion of Dr. Eugene P. Wigner to attack the problem of the distortion of graphite in the early reactors due to exposure to reactor neutrons, and the consequent radiation damage. It was called the Metallurgy Division and assembled the metallurgical and solid state physics activities of the time which were not directly related to nuclear weapons production. William A. Johnson, a Westinghouse employee, was named Division Director in 1946. In 1949 he was replaced by John H Frye Jr. when the Division consisted of 45 people. He was director during most of what is called the Reactor Project Years until 1973 and his retirement. During this period the Division evolved into three organizational areas: basic research, applied research in nuclear reactor materials, and reactor programs directly related to a specific reactor(s) being designed or built. The Division (Metals and Ceramics) consisted of 204 staff members in 1973 when James R. Weir, Jr., became Director. This was the period of the oil embargo, the formation of the Energy Research and Development Administration (ERDA) by combining the Atomic Energy Commission (AEC) with the Office of Coal Research, and subsequent formation of the Department of Energy (DOE). The diversification process continued when James O. Stiegler became Director in 1984, partially as a result of the pressure of legislation encouraging the national laboratories to work with U.S. industries on their problems. During that time the Division staff grew from 265 to 330. Douglas F. Craig became Director in 1992.

Automated external defibrillators in National Collegiate Athletic Association Division I Athletics.

Science.gov (United States)

Coris, Eric E; Sahebzamani, Frances; Walz, Steve; Ramirez, Arnold M

2004-01-01

Sudden cardiac death is the leading cause of death in athletes. Evidence on current sudden cardiac death prevention through preparticipation history, physicals, and noninvasive cardiovascular diagnostics has demonstrated a low sensitivity for detection of athletes at high risk of sudden cardiac death. Data are lacking on automated external defibrillator programs specifically initiated to respond to rare dysrhythmia in younger, relatively low-risk populations. Surveys were mailed to the head athletic trainers of all National Collegiate Athletic Association Division I athletics programs listed in the National Athletic Trainers' Association directory. In all, 303 surveys were mailed; 186 departments (61%) responded. Seventy-two percent (133) of responding National Collegiate Athletic Association Division I athletics programs have access to automated external defibrillator units; 54% (101) own their units. Proven medical benefit (55%), concern for liability (51%), and affordability (29%) ranked highest in frequency of reasons for automated external defibrillator purchase. Unit cost (odds ratio = 1.01; 95% confidence interval, 1.01-1.0), donated units (odds ratio = 1.92; confidence interval, 3.66-1.01), institution size (odds ratio =.0001; confidence interval, 1.3 E-4 to 2.2E-05), and proven medical benefit of automated external defibrillators (odds ratio = 24; confidence interval, 72-8.1) were the most significant predictors of departmental defibrillator ownership. Emergency medical service response time and sudden cardiac death event history were not significantly predictive of departmental defibrillator ownership. The majority of automated external defibrillator interventions occurred on nonathletes. Many athletics medicine programs are obtaining automated external defibrillators without apparent criteria for determination of need. Usage and maintenance policies vary widely among departments with unit ownership or access. Programs need to approach the issue of unit

Duration judgements over multiple elements

Directory of Open Access Journals (Sweden)

Inci eAyhan

2012-11-01

Full Text Available We investigated the limits of the number of events observers can simultaneously time. For single targets occurring in one of eight positions sensitivity to duration was improved for spatially pre-cued items as compared to post-cued items indicating that exogenous driven attention can improve duration discrimination. Sensitivity to duration for pre-cued items was also marginally better for single items as compared to eight items indicating that even after the allocation of focal attention, distracter items can interfere with the encoding of duration. For an eight item array discrimination was worse for post-cued locations as compared to pre-cued locations indicating both that attention can improve duration discrimination performance and that it was not possible to access a perfect memory trace of the duration of eight elements. The interference from the distracters in the pre-cued eight item array may reflect some mandatory averaging of target and distracter events. To further explore duration averaging we asked subjects to explicitly compare average durations of multiple item arrays against a single item standard duration. Duration discrimination thresholds were significantly lower for single elements as compared to multiple elements, showing that averaging, either automatically or intentionally, impairs duration discrimination. There was no set size effect. Performance was the same for averages of two and eight items, but performance with even an average of two items was worse than for one item. This was also true for sequential presentation indicating poor performance was not due to limits on the division of attention across items. Rather performance appears to be limited by an inability to remember or aggregate duration information from two or more items. Although it is possible to manipulate perceived duration locally, there appears to be no perceptual mechanisms for aggregating local durations across space.

Theoretical physics division

International Nuclear Information System (INIS)

Anon.

1980-01-01

Research activities of the theoretical physics division for 1979 are described. Short summaries are given of specific research work in the following fields: nuclear structure, nuclear reactions, intermediate energy physics, elementary particles [fr

Atmospheric and Geophysical Sciences Division: Program report, FY 1987

International Nuclear Information System (INIS)

1988-05-01

In 1988 the Atmospheric and Geophysical Sciences Division began its 15th year as a division. As the Division has grown over the years, its modeling capabilities have expanded to include a broad range of time and space scales ranging from hours to years, and from kilometers to global, respectively. For this report, we have chosen to show a subset of results from several projects to illustrate the breadth, depth, and diversity of the modeling activities that are a major part of the Division's research, development, and application efforts. In addition, the recent reorganization of the Division, including the merger of another group with the Division, is described, and the budget, personnel, models, and publications are reviewed. 95 refs., 26 figs., 2 tabs

Orthogonal Multi-Carrier DS-CDMA with Frequency-Domain Equalization

Science.gov (United States)

Tanaka, Ken; Tomeba, Hiromichi; Adachi, Fumiyuki

Orthogonal multi-carrier direct sequence code division multiple access (orthogonal MC DS-CDMA) is a combination of orthogonal frequency division multiplexing (OFDM) and time-domain spreading, while multi-carrier code division multiple access (MC-CDMA) is a combination of OFDM and frequency-domain spreading. In MC-CDMA, a good bit error rate (BER) performance can be achieved by using frequency-domain equalization (FDE), since the frequency diversity gain is obtained. On the other hand, the conventional orthogonal MC DS-CDMA fails to achieve any frequency diversity gain. In this paper, we propose a new orthogonal MC DS-CDMA that can obtain the frequency diversity gain by applying FDE. The conditional BER analysis is presented. The theoretical average BER performance in a frequency-selective Rayleigh fading channel is evaluated by the Monte-Carlo numerical computation method using the derived conditional BER and is confirmed by computer simulation of the orthogonal MC DS-CDMA signal transmission.

Couples’ Attitudes, Childbirth, and the Division of Labor

NARCIS (Netherlands)

Jansen, Miranda; Liefbroer, Aart C.

2006-01-01

In this article, the authors examine effects of partners’ attitudes on the timing of the birth of a first child, the division of domestic labor, the division of child care, and the division of paid labor of couples. They use data from the Panel Study of Social Integration in the Netherlands, which

Division of labour in the yeast

DEFF Research Database (Denmark)

Wloch-Salamon, Dominika M.; Fisher, Roberta May; Regenberg, Birgitte

2017-01-01

. Saccharomyces cerevisiae displays several phenotypes that could be considered a division of labour, including quiescence, apoptosis and biofilm formation, but they have not been explicitly treated as such. We discuss each of these examples, using a definition of division of labour that involves phenotypic...... variation between cells within a population, cooperation between cells performing different tasks and maximization of the inclusive fitness of all cells involved. We then propose future research directions and possible experimental tests using S. cerevisiae as a model organism for understanding the genetic...... mechanisms and selective pressures that can lead to the evolution of the very first stages of a division of labour....

Radioactive Waste and Clean-up Division

International Nuclear Information System (INIS)

Collard, G.

2001-01-01

The main objectives of the Radioactive Waste and Clean-up division of SCK-CEN are outlined. The division's programme consists of research, development and demonstration projects and aims to contribute to the objectives of Agenda 21 on sustainable development in the field of radioactive waste and rehabilitation of radioactively contaminated sites

A SURVEY ON WAVELENGTH DIVISION MULTIPLEXING (WDM NETWORKS

Directory of Open Access Journals (Sweden)

G. Ramesh

2010-03-01

Full Text Available Communication networks have emerged as a source of empowerment in today’s society. At the global level, the Internet is becoming the backbone of the modern economy. The new generations in developed countries cannot even conceive of a world without broadband access to the Internet. The inability of the current Internet infrastructure to cope with the wide variety and ever growing number of users, emerging networked applications, usage patterns and business models is increasingly being recognized worldwide. The dynamic growth of Internet traffic and its bursty nature requires high transmission rate. With the advances and the progress in Wavelength Division Multiplexing (WDM technology, the amount of raw bandwidth available in fiber links has increased to high magnitude. This paper presents a survey on WDM networks from its development to the current status. Also an analysis on buffer size in optical networks for real time traffic was performed.

Energy Technology Division research summary -- 1994

Energy Technology Data Exchange (ETDEWEB)

1994-09-01

Research funded primarily by the NRC is directed toward assessing the roles of cyclic fatigue, intergranular stress corrosion cracking, and irradiation-assisted stress corrosion cracking on failures in light water reactor (LWR) piping systems, pressure vessels, and various core components. In support of the fast reactor program, the Division has responsibility for fuel-performance modeling and irradiation testing. The Division has major responsibilities in several design areas of the proposed International Thermonuclear Experimental Reactor (ITER). The Division supports the DOE in ensuring safe shipment of nuclear materials by providing extensive review of the Safety Analysis Reports for Packaging (SARPs). Finally, in the nuclear area they are investigating the safe disposal of spent fuel and waste. In work funded by DOE`s Energy Efficiency and Renewable Energy, the high-temperature superconductivity program continues to be a major focal point for industrial interactions. Coatings and lubricants developed in the division`s Tribology Section are intended for use in transportation systems of the future. Continuous fiber ceramic composites are being developed for high-performance heat engines. Nondestructive testing techniques are being developed to evaluate fiber distribution and to detect flaws. A wide variety of coatings for corrosion protection of metal alloys are being studied. These can increase lifetimes significant in a wide variety of coal combustion and gasification environments.

Atmospheric and Geophysical Sciences Division Program Report, 1988--1989

Energy Technology Data Exchange (ETDEWEB)

1990-06-01

In 1990, the Atmospheric and Geophysical Sciences Division begins its 17th year as a division. As the Division has grown over the years, its modeling capabilities have expanded to include a broad range of time and space scales ranging from hours to decades and from local to global. Our modeling is now reaching out from its atmospheric focus to treat linkages with the oceans and the land. In this report, we describe the Division's goal and organizational structure. We also provide tables and appendices describing the Division's budget, personnel, models, and publications. 2 figs., 1 tab.

Biology Division progress report, October 1, 1991--September 30, 1993

Energy Technology Data Exchange (ETDEWEB)

Hartman, F.C.; Cook, J.S.

1993-10-01

This Progress Report summarizes the research endeavors of the Biology Division of the Oak Ridge National Laboratory during the period October 1, 1991, through September 30, 1993. The report is structured to provide descriptions of current activities and accomplishments in each of the Division`s major organizational units. Lists of information to convey the entire scope of the Division`s activities are compiled at the end of the report.

Radix-16 Combined Division and Square Root Unit

DEFF Research Database (Denmark)

Nannarelli, Alberto

2011-01-01

Division and square root, based on the digitrecurrence algorithm, can be implemented in a combined unit. Several implementations of combined division/square root units have been presented mostly for radices 2 and 4. Here, we present a combined radix-16 unit obtained by overlapping two radix-4...... result digit selection functions, as it is normally done for division only units. The latency of the unit is reduced by retiming and low power methods are applied as well. The proposed unit is compared to a radix-4 combined division/square root unit, and to a radix-16 unit, obtained by cascading two...

Chemical Technology Division Annual Report 2000

International Nuclear Information System (INIS)

Lewis, D.; Gay, E. C.; Miller, J. F.; Einziger, R. E.; Green, D. W.

2001-01-01

The Chemical Technology Division (CMT) is one of eight engineering research divisions within Argonne National Laboratory (ANL), one of the U.S. government's oldest and largest research laboratories. The University of Chicago oversees the laboratory on behalf of the U.S. Department of Energy (DOE). Argonne's mission is to conduct basic scientific research, to operate national scientific facilities, to enhance the nation's energy resources, and to develop better ways to manage environmental problems. Argonne has the further responsibility of strengthening the nation's technology base through developing industrial technology and transferring that technology to industry. The Chemical Technology Division is a diverse early-stage engineering organization, specializing in the treatment of spent nuclear fuel, development of advanced power sources, and management of both high- and low-level nuclear wastes. Although this work is often indistinguishable from basic research, our efforts are directed toward the practical devices and processes that are covered by ANL's mission. Additionally, the Division operates the Analytical Chemistry Laboratory, which provides a broad range of analytical services to ANL and other organizations. The Division is multi-disciplinary. Its people have formal training as ceramists; physicists; material scientists; electrical, mechanical, chemical, and nuclear engineers; and chemists. They have experience working in academia, urban planning, and the petroleum, aluminum, and automotive industries. Their skills include catalysis, ceramics, electrochemistry, metallurgy, nuclear magnetic resonance spectroscopy, and petroleum refining, as well as the development of nuclear waste forms, batteries, and high-temperature superconductors. In this annual report we present an overview of the technical programs together with representative highlights. The report is not intended to be comprehensive or encyclopedic, but to serve as an indication of the condition

Materials Sciences Division 1990 annual report

Energy Technology Data Exchange (ETDEWEB)

1990-12-31

This report is the Materials Sciences Division`s annual report. It contains abstracts describing materials research at the National Center for Electron Microscopy, and for research groups in metallurgy, solid-state physics, materials chemistry, electrochemical energy storage, electronic materials, surface science and catalysis, ceramic science, high tc superconductivity, polymers, composites, and high performance metals.

Earth Sciences Division, collected abstracts-1977

International Nuclear Information System (INIS)

Quitiquit, W.A.; Ledbetter, G.P.; Henry, A.L.

1978-01-01

This report is a compilation of abstracts of papers, internal reports, and talks presented during 1977 at national and international meetings by members of the Earth Sciences Division, Lawrence Livermore Laboratory. It is arranged alphabetically by author and includes a cross-reference by subject indicating the areas of research interest of the Earth Sciences Division

Nuclear size and cell division delay

International Nuclear Information System (INIS)

Bird, R.P.

1986-01-01

Radiation-induced division delay has been linked to damage at the nuclear envelope. Further, cells in G 2 phase are drastically arrested by high LET radiation such that single particles traversing cell nuclei may produce measurable division delay. A modest effort was initiated using two related cell lines of different size, near-diploid cells and near-tetraploid cells of Chinese hamster origin, to compare their sensitivity for radiation-induced division delay. If the nuclear surface is the critical target, then a larger nuclear cross-section presented to an alpha-particle beam should exhibit delay induced by a lesser particle fluence. Preliminary estimates of the extent of delay in asynchronous cultures following low doses of gamma-irradiation or of alpha-irradiation were made by in-situ observation of the time of onset of mitosis and by fixation and staining of cultures to determine the mitotic index as a function of time after irradiation. The basic approach to evaluating division delay will be to use Colecemid to accumulate mitotic cells over a period of time

Individuality and universality in the growth-division laws of single E. coli cells

Science.gov (United States)

Kennard, Andrew S.; Osella, Matteo; Javer, Avelino; Grilli, Jacopo; Nghe, Philippe; Tans, Sander J.; Cicuta, Pietro; Cosentino Lagomarsino, Marco

2016-01-01

The mean size of exponentially dividing Escherichia coli cells in different nutrient conditions is known to depend on the mean growth rate only. However, the joint fluctuations relating cell size, doubling time, and individual growth rate are only starting to be characterized. Recent studies in bacteria reported a universal trend where the spread in both size and doubling times is a linear function of the population means of these variables. Here we combine experiments and theory and use scaling concepts to elucidate the constraints posed by the second observation on the division control mechanism and on the joint fluctuations of sizes and doubling times. We found that scaling relations based on the means collapse both size and doubling-time distributions across different conditions and explain how the shape of their joint fluctuations deviates from the means. Our data on these joint fluctuations highlight the importance of cell individuality: Single cells do not follow the dependence observed for the means between size and either growth rate or inverse doubling time. Our calculations show that these results emerge from a broad class of division control mechanisms requiring a certain scaling form of the "division hazard rate function," which defines the probability rate of dividing as a function of measurable parameters. This "model free" approach gives a rationale for the universal body-size distributions observed in microbial ecosystems across many microbial species, presumably dividing with multiple mechanisms. Additionally, our experiments show a crossover between fast and slow growth in the relation between individual-cell growth rate and division time, which can be understood in terms of different regimes of genome replication control.

Uniform Circular Antenna Array Applications in Coded DS-CDMA Mobile Communication Systems

National Research Council Canada - National Science Library

Seow, Tian

2003-01-01

...) has greatly increased. This thesis examines the use of an equally spaced circular adaptive antenna array at the mobile station for a typical coded direct sequence code division multiple access (DS-CDMA...

Femtosecond Laser System for Research on High-Speed Optical Transmultiplexing and Coding

National Research Council Canada - National Science Library

Weiner, Andrew

1997-01-01

.... This would fill an important need in both TDM packet networks and bit-parallel WDM linds. The research also aims at experimental tests of an ultrashort pulse code-division, multiple-access (CDMA...

Radiochemistry Division annual progress report : 1992

International Nuclear Information System (INIS)

Natarajan, V.; Godbole, S.V.; Iyer, R.H.

1994-01-01

The research and development activities of the Radiochemistry Division during 1992 are briefly described in the form of individual summaries grouped under the headings: 1) Nuclear Chemistry, 2) Actinide Chemistry, 3) Spectroscopy, and 4) Instrumentation. A list of publications numbering 95 by the scientific staff of the Division is also included in the report. (author). 35 figs., 56 tabs

Division of Labor

KAUST Repository

Oke, Muse; Zaher, Manal S.; Hamdan, Samir

2014-01-01

The first assignment of DNA polymerases at the eukaryotic replication fork was possible after the in vitro reconstitution of the simian virus 40 (SV40) replication system. In this system, DNA polymerase α (Pol α) provides both leading and lagging strands with RNA-DNA primers that are extended by DNA polymerase δ (Pol δ). Extrapolating the architecture of the replication fork from the SV40 model system to an actual eukaryotic cell has been challenged by the discovery of a third DNA polymerase in Saccharomyces cerevisiae, DNA polymerase ε (Pol ε). A division of labor has been proposed for the eukaryotic replication fork whereby Pol ε replicates the leading strand and Pol δ replicates the lagging strand. However, an alternative model of unequal division of labor in which Pol δ can still participate in leading-strand synthesis is plausible.

Division of Labor

KAUST Repository

Oke, Muse

2014-09-12

The first assignment of DNA polymerases at the eukaryotic replication fork was possible after the in vitro reconstitution of the simian virus 40 (SV40) replication system. In this system, DNA polymerase α (Pol α) provides both leading and lagging strands with RNA-DNA primers that are extended by DNA polymerase δ (Pol δ). Extrapolating the architecture of the replication fork from the SV40 model system to an actual eukaryotic cell has been challenged by the discovery of a third DNA polymerase in Saccharomyces cerevisiae, DNA polymerase ε (Pol ε). A division of labor has been proposed for the eukaryotic replication fork whereby Pol ε replicates the leading strand and Pol δ replicates the lagging strand. However, an alternative model of unequal division of labor in which Pol δ can still participate in leading-strand synthesis is plausible.

Physics division. Progress report, January 1, 1995--December 31, 1996

International Nuclear Information System (INIS)

Stewart, M.; Bacon, D.S.; Aine, C.J.; Bartsch, R.R.

1997-10-01

This issue of the Physics Division Progress Report describes progress and achievements in Physics Division research during the period January 1, 1995-December 31, 1996. The report covers the five main areas of experimental research and development in which Physics Division serves the needs of Los Alamos National Laboratory and the nation in applied and basic sciences: (1) biophysics, (2) hydrodynamic physics, (3) neutron science and technology, (4) plasma physics, and (5) subatomic physics. Included in this report are a message from the Division Director, the Physics Division mission statement, an organizational chart, descriptions of the research areas of the five groups in the Division, selected research highlights, project descriptions, the Division staffing and funding levels for FY95-FY97, and a list of publications and presentations

Physics division. Progress report, January 1, 1995--December 31, 1996

Energy Technology Data Exchange (ETDEWEB)

Stewart, M.; Bacon, D.S.; Aine, C.J.; Bartsch, R.R. [eds.] [comps.] [and others

1997-10-01

This issue of the Physics Division Progress Report describes progress and achievements in Physics Division research during the period January 1, 1995-December 31, 1996. The report covers the five main areas of experimental research and development in which Physics Division serves the needs of Los Alamos National Laboratory and the nation in applied and basic sciences: (1) biophysics, (2) hydrodynamic physics, (3) neutron science and technology, (4) plasma physics, and (5) subatomic physics. Included in this report are a message from the Division Director, the Physics Division mission statement, an organizational chart, descriptions of the research areas of the five groups in the Division, selected research highlights, project descriptions, the Division staffing and funding levels for FY95-FY97, and a list of publications and presentations.

Opportunistic spectrum access in cognitive radio based on channel switching

KAUST Repository

Gaaloul, Fakhreddine; Yang, Hongchuan; Radaydeh, Redha Mahmoud Mesleh; Alouini, Mohamed-Slim

2012-01-01

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

Nuclear Chemistry Division annual report FY83

International Nuclear Information System (INIS)

Struble, G.

1983-01-01

The purpose of the annual reports of the Nuclear Chemistry Division is to provide a timely summary of research activities pursued by members of the Division during the preceding year. Throughout, details are kept to a minimum; readers desiring additional information are encouraged to read the referenced documents or contact the authors. The Introduction presents an overview of the Division's scientific and technical programs. Next is a section of short articles describing recent upgrades of the Division's major facilities, followed by sections highlighting scientific and technical advances. These are grouped under the following sections: nuclear explosives diagnostics; geochemistry and environmental sciences; safeguards technology and radiation effect; and supporting fundamental science. A brief overview introduces each section. Reports on research supported by a particular program are generally grouped together in the same section. The last section lists the scientific, administrative, and technical staff in the Division, along with visitors, consultants, and postdoctoral fellows. It also contains a list of recent publications and presentations. Some contributions to the annual report are classified and only their abstracts are included in this unclassified portion of the report (UCAR-10062-83/1); the full article appears in the classified portion (UCAR-10062-83/2)

The ACS-NUCL Division 50th Anniversary: Introduction

Energy Technology Data Exchange (ETDEWEB)

Hobart, David E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-01-10

The ACS Division of Nuclear Chemistry and Technology was initiated in 1955 as a subdivision of the Division of Industrial and Engineering Chemistry. Probationary divisional status was lifted in 1965. The Division’s first symposium was held in Denver in 1964 and it is fitting that we kicked-off the 50th Anniversary in Denver in the spring of 2015. Listed as a small ACS Division with only about 1,000 members, NUCL’s impact over the past fifty years has been remarkable. National ACS meetings have had many symposia sponsored or cosponsored by NUCL that included Nobel Laureates, U.S. Senators, other high-ranking officials and many students as speakers. The range of subjects has been exceptional as are the various prestigious awards established by the Division. Of major impact has been the past 30 years of the NUCL Nuclear Chemistry Summer Schools to help fill the void of qualified nuclear scientists and technicians. In celebrating the 50th Anniversary we honor the past, celebrate the present and shape the future of the Division and nuclear science and technology. To celebrate this auspicious occasion a commemorative lapel pin has been designed for distribution to NUCL Division members.

24 CFR 4.36 - Action by the Ethics Law Division.

Science.gov (United States)

2010-04-01

... violation is material, the Ethics Law Division shall consider the following factors, as applicable: (1) The... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Action by the Ethics Law Division... the Ethics Law Division. (a) After review of the Inspector General's report, the Ethics Law Division...

All-optical VPN utilizing DSP-based digital orthogonal filters access for PONs

Science.gov (United States)

Zhang, Xiaoling; Zhang, Chongfu; Chen, Chen; Jin, Wei; Qiu, Kun

2018-04-01

Utilizing digital filtering-enabled signal multiplexing and de-multiplexing, a cost-effective all-optical virtual private network (VPN) system is proposed, for the first time to our best knowledge, in digital filter multiple access passive optical networks (DFMA-PONs). Based on the DFMA technology, the proposed system can be easily designed to meet the requirements of next generation network's flexibility, elasticity, adaptability and compatibility. Through dynamic digital filter allocation and recycling, the proposed all-optical VPN system can provide dynamic establishments and cancellations of multiple VPN communications with arbitrary traffic volumes. More importantly, due to the employment of DFMA technology, the system is not limited to a fixed signal format and different signal formats such as pulse amplitude modulation (PAM), quadrature amplitude modulation (QAM) and orthogonal frequency division multiplexing (OFDM) can be used. Moreover, one transceiver is sufficient to simultaneously transmit upstream (US)/VPN data to optical line terminal (OLT) or other VPN optical network units (ONUs), thus leading to great reduction in network constructions and operation expenditures. The proposed all-optical VPN system is demonstrated with the transceiver incorporating the formats of QAM and OFDM, which can be made transparent to downstream (DS), US and VPN communications. The bit error rates (BERs) of DS, US and VPN for OFDM signals are below the forward-error-correction (FEC) limit of 3 . 8 × 10-3 when the received optical powers are about -16.8 dBm, -14.5 dBm and -15.7 dBm, respectively.

Lowering data retention voltage in static random access memory array by post fabrication self-improvement of cell stability by multiple stress application

Science.gov (United States)

Mizutani, Tomoko; Takeuchi, Kiyoshi; Saraya, Takuya; Kobayashi, Masaharu; Hiramoto, Toshiro

2018-04-01

We propose a new version of the post fabrication static random access memory (SRAM) self-improvement technique, which utilizes multiple stress application. It is demonstrated that, using a device matrix array (DMA) test element group (TEG) with intrinsic channel fully depleted (FD) silicon-on-thin-buried-oxide (SOTB) six-transistor (6T) SRAM cells fabricated by the 65 nm technology, the lowering of data retention voltage (DRV) is more effectively achieved than using the previously proposed single stress technique.

Content sensitivity based access control framework for Hadoop

Directory of Open Access Journals (Sweden)

T.K. Ashwin Kumar

2017-11-01

Full Text Available Big data technologies have seen tremendous growth in recent years. They are widely used in both industry and academia. In spite of such exponential growth, these technologies lack adequate measures to protect data from misuse/abuse. Corporations that collect data from multiple sources are at risk of liabilities due to the exposure of sensitive information. In the current implementation of Hadoop, only file-level access control is feasible. Providing users with the ability to access data based on the attributes in a dataset or the user’s role is complicated because of the sheer volume and multiple formats (structured, unstructured and semi-structured of data. In this paper, we propose an access control framework, which enforces access control policies dynamically based on the sensitivity of the data. This framework enforces access control policies by harnessing the data context, usage patterns and information sensitivity. Information sensitivity changes over time with the addition and removal of datasets, which can lead to modifications in access control decisions. The proposed framework accommodates these changes. The proposed framework is automated to a large extent as the data itself determines the sensitivity with minimal user intervention. Our experimental results show that the proposed framework is capable of enforcing access control policies on non-multimedia datasets with minimal overhead.

A Resistance-Nodulation-Cell Division Family Xenobiotic Efflux Pump in an Obligate Anaerobe, Porphyromonas gingivalis

OpenAIRE

Ikeda, Takeshi; Yoshimura, Fuminobu

2002-01-01

Porphyromonas gingivalis, a gram-negative obligate anaerobe, contains two homologs of an Escherichia coli resistance-nodulation-cell division-type multidrug exporter gene, acrB, in putative operons, together with homologs of membrane fusion protein gene acrA and outer membrane channel gene tolC. MIC determination and accumulation assays with mutants with disruptions of one or more genes showed that one cluster, named xepCAB, pumped out multiple agents including rifampin, puromycin, and ethidi...

Lead from the center. How to manage divisions dynamically.

Science.gov (United States)

Raynor, M E; Bower, J L

2001-05-01

Conventional wisdom holds that a company's divisions should be given almost total autonomy--especially under conditions of uncertainty--because they are closer to emerging technologies, customers, and competitors than corporate headquarters could ever be. But research from Michael Raynor and Joseph Bower suggests that the corporate office should be more, not less, directive in turbulent markets. Rapid changes in an industry make it difficult to predict where and when synergies among divisions might emerge. With so many possibilities and such uncertainty, companies can't afford to sacrifice their ability to flexibly execute business strategy. Corporate headquarters must play an active role in defining the scope of division-level strategy, the authors say, so that divisions do not act in ways that undermine opportunities to collaborate in the future. But neither can companies afford to sacrifice the competitiveness of their divisions as stand-alone businesses. In creating corporate-level strategic flexibility, a corporate office must balance the need for divisional autonomy now with the potential need for cooperation in the future. Through an examination of four corporations--Sprint, WPP, Teradyne, and Viacom--the authors challenge traditional approaches to diversification in which a company's divisions are either related (they share resources and collaborate) or unrelated (they compete for resources and operate as stand-alone businesses). They argue that companies should adopt a dynamic approach to cooperation among divisions, enabling varying degrees of relatedness between divisions depending on strategic circumstances. The authors offer four tactics to help executives manage divisions dynamically.

Sequence Selection and Performance in DS/CDMA Systems

Directory of Open Access Journals (Sweden)

Jefferson Santos Ambrosio

2016-03-01

Full Text Available In this work key concepts on coding division multiple access (CDMA communication systems have been discussed. The sequence selection impact on the performance and capacity of direct sequence CDMA (DS/CDMA systems under AWGN and increasing system loading, as well as under multiple antennas channels was investigated.

Reactor Engineering Division Material for World Wide Web Pages

International Nuclear Information System (INIS)

1996-01-01

This document presents the home page of the Reactor Engineering Division of Argonne National Laboratory. This WWW site describes the activities of the Division, an introduction to its wide variety of programs and samples of the results of research by people in the division

Medical Sciences Division report for 1993

Energy Technology Data Exchange (ETDEWEB)

1993-12-31

This year`s Medical Sciences Division (MSD) Report is organized to show how programs in our division contribute to the core competencies of Oak Ridge Institute for Science and Education (ORISE). ORISE`s core competencies in education and training, environmental and safety evaluation and analysis, occupational and environmental health, and enabling research support the overall mission of the US Department of Energy (DOE).

Medical Sciences Division report for 1993

International Nuclear Information System (INIS)

1993-01-01

This year's Medical Sciences Division (MSD) Report is organized to show how programs in our division contribute to the core competencies of Oak Ridge Institute for Science and Education (ORISE). ORISE's core competencies in education and training, environmental and safety evaluation and analysis, occupational and environmental health, and enabling research support the overall mission of the US Department of Energy (DOE)

Genetic components to caste allocation in a multiple-queen ant species

NARCIS (Netherlands)

Libbrecht, Romain; Schwander, Tanja; Keller, Laurent

2011-01-01

Reproductive division of labor and the coexistence of distinct castes are hallmarks of insect societies. In social insect species with multiple queens per colony, the fitness of nestmate queens directly depends on the process of caste allocation (i.e., the relative investment in queen, sterile

A dynamic new group within Human Resources Division

CERN Multimedia

2003-01-01

Since 1st May CERN's training and development and personnel management teams have been fused into a new group called Personnel Management and Development. The new Personnel Management and Development Group is responsible for career advancement and management, recruitment, remuneration and for language, communication, management, academic and technical training, keys to a sense of greater well-being and to career progression. The new group was born on 1st May out of the fusion of the "Personnel Management" and "Training and Development" Groups within CERN's Human Resources Division. Its aim is to offer a practical and easily accessible service to assist the members of the personnel and supervisors to manage careers more harmoniously, to make progress and to continue to learn on the job. With Sue Foffano as its Group Leader, the Group comprises four sections: Academic and Technical Training under the guiding hand of Mick Storr; Management, Communication and Language Training headed by Sudeshna Datta-Cockeril...

Division of labour in the yeast: Saccharomyces cerevisiae.

Science.gov (United States)

Wloch-Salamon, Dominika M; Fisher, Roberta M; Regenberg, Birgitte

2017-10-01

Division of labour between different specialized cell types is a central part of how we describe complexity in multicellular organisms. However, it is increasingly being recognized that division of labour also plays an important role in the lives of predominantly unicellular organisms. Saccharomyces cerevisiae displays several phenotypes that could be considered a division of labour, including quiescence, apoptosis and biofilm formation, but they have not been explicitly treated as such. We discuss each of these examples, using a definition of division of labour that involves phenotypic variation between cells within a population, cooperation between cells performing different tasks and maximization of the inclusive fitness of all cells involved. We then propose future research directions and possible experimental tests using S. cerevisiae as a model organism for understanding the genetic mechanisms and selective pressures that can lead to the evolution of the very first stages of a division of labour. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

15 CFR 950.8 - Satellite Data Services Division (SDSD).

Science.gov (United States)

2010-01-01

... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false Satellite Data Services Division (SDSD... THE ENVIRONMENTAL DATA SERVICE ENVIRONMENTAL DATA AND INFORMATION § 950.8 Satellite Data Services Division (SDSD). The Satellite Data Services Division of the EDIS National Climatic Center provides...

Division of Agriculture

Science.gov (United States)

Department of Natural Resources logo, color scheme Department of Natural Resources Division of Agriculture Search Search DNR's site DNR State of Alaska Toggle main menu visibility Agriculture Home Programs Asset Disposals Alaska Caps Progam Board of Agriculture & Conservation Farm To School Program Grants

Quantitative regulation of B cell division destiny by signal strength.

Science.gov (United States)

Turner, Marian L; Hawkins, Edwin D; Hodgkin, Philip D

2008-07-01

Differentiation to Ab secreting and isotype-switched effector cells is tightly linked to cell division and therefore the degree of proliferation strongly influences the nature of the immune response. The maximum number of divisions reached, termed the population division destiny, is stochastically distributed in the population and is an important parameter in the quantitative outcome of lymphocyte responses. In this study, we further assessed the variables that regulate B cell division destiny in vitro in response to T cell- and TLR-dependent stimuli. Both the concentration and duration of stimulation were able to regulate the average maximum number of divisions undergone for each stimulus. Notably, a maximum division destiny was reached during provision of repeated saturating stimulation, revealing that an intrinsic limit to proliferation exists even under these conditions. This limit was linked directly to division number rather than time of exposure to stimulation and operated independently of the survival regulation of the cells. These results demonstrate that a B cell population's division destiny is regulable by the stimulatory conditions up to an inherent maximum value. Division destiny is a crucial parameter in regulating the extent of B cell responses and thereby also the nature of the immune response mounted.

Application of WLF to OFDMA MU-MIMO Systems I: Frequency-Domain Equalization

OpenAIRE

Xiao, P; Lin, Z; Wu, Y; Schneider, C

2013-01-01

This paper presents a novel iterative receiver strategy incorporating widely linear filtering for uplink Orthogonal Frequency Division Multiple Access (OFDMA) multiuser multiple-input, multiple-output (MIMO) systems. The proposed iterative receiver scheme achieves better performance without the loss of spectrum efficiency compared to the conventional iterative receivers; The superiority of the investigated scheduler coupled with the innovative iterative receiver scheme over conventional solut...

Parkin suppresses Drp1-independent mitochondrial division

Energy Technology Data Exchange (ETDEWEB)

Roy, Madhuparna, E-mail: mroy17@jhmi.edu; Itoh, Kie, E-mail: kito5@jhmi.edu; Iijima, Miho, E-mail: miijima@jhmi.edu; Sesaki, Hiromi, E-mail: hsesaki@jhmi.edu

2016-07-01

The cycle of mitochondrial division and fusion disconnect and reconnect individual mitochondria in cells to remodel this energy-producing organelle. Although dynamin-related protein 1 (Drp1) plays a major role in mitochondrial division in cells, a reduced level of mitochondrial division still persists even in the absence of Drp1. It is unknown how much Drp1-mediated mitochondrial division accounts for the connectivity of mitochondria. The role of a Parkinson’s disease-associated protein—parkin, which biochemically and genetically interacts with Drp1—in mitochondrial connectivity also remains poorly understood. Here, we quantified the number and connectivity of mitochondria using mitochondria-targeted photoactivatable GFP in cells. We show that the loss of Drp1 increases the connectivity of mitochondria by 15-fold in mouse embryonic fibroblasts (MEFs). While a single loss of parkin does not affect the connectivity of mitochondria, the connectivity of mitochondria significantly decreased compared with a single loss of Drp1 when parkin was lost in the absence of Drp1. Furthermore, the loss of parkin decreased the frequency of depolarization of the mitochondrial inner membrane that is caused by increased mitochondrial connectivity in Drp1-knockout MEFs. Therefore, our data suggest that parkin negatively regulates Drp1-indendent mitochondrial division. -- Highlights: •A Drp1-mediated mechanism accounts for ∼95% of mitochondrial division. •Parkin controls the connectivity of mitochondria via a mechanism that is independent of Drp1. •In the absence of Drp1, connected mitochondria transiently depolarize. •The transient depolarization is independent of calcium signaling and uncoupling protein 2.

Parkin suppresses Drp1-independent mitochondrial division

International Nuclear Information System (INIS)

Roy, Madhuparna; Itoh, Kie; Iijima, Miho; Sesaki, Hiromi

2016-01-01

The cycle of mitochondrial division and fusion disconnect and reconnect individual mitochondria in cells to remodel this energy-producing organelle. Although dynamin-related protein 1 (Drp1) plays a major role in mitochondrial division in cells, a reduced level of mitochondrial division still persists even in the absence of Drp1. It is unknown how much Drp1-mediated mitochondrial division accounts for the connectivity of mitochondria. The role of a Parkinson’s disease-associated protein—parkin, which biochemically and genetically interacts with Drp1—in mitochondrial connectivity also remains poorly understood. Here, we quantified the number and connectivity of mitochondria using mitochondria-targeted photoactivatable GFP in cells. We show that the loss of Drp1 increases the connectivity of mitochondria by 15-fold in mouse embryonic fibroblasts (MEFs). While a single loss of parkin does not affect the connectivity of mitochondria, the connectivity of mitochondria significantly decreased compared with a single loss of Drp1 when parkin was lost in the absence of Drp1. Furthermore, the loss of parkin decreased the frequency of depolarization of the mitochondrial inner membrane that is caused by increased mitochondrial connectivity in Drp1-knockout MEFs. Therefore, our data suggest that parkin negatively regulates Drp1-indendent mitochondrial division. -- Highlights: •A Drp1-mediated mechanism accounts for ∼95% of mitochondrial division. •Parkin controls the connectivity of mitochondria via a mechanism that is independent of Drp1. •In the absence of Drp1, connected mitochondria transiently depolarize. •The transient depolarization is independent of calcium signaling and uncoupling protein 2.

Publications - Geospatial Data | Alaska Division of Geological &

Science.gov (United States)

from rocks collected in the Richardson mining district, Big Delta Quadrangle, Alaska: Alaska Division Island 2009 topography: Alaska Division of Geological & Geophysical Surveys Miscellaneous Publication , Geologic map of portions of the Livengood B-3, B-4, C-3, and C-4 quadrangles, Tolovana mining district

Biology Division progress report, October 1, 1993--September 30, 1995

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-10-01

This Progress Report summarizes the research endeavors of the Biology Division of the Oak Ridge National Laboratory during the period October 1, 1993, through September 30, 1995. The report is structured to provide descriptions of current activities and accomplishments in each of the Division`s major organizational units. Lists of information to convey the entire scope of the Division`s activities are compiled at the end of the report. Attention is focused on the following research activities: molecular, cellular, and cancer biology; mammalian genetics and development; genome mapping program; and educational activities.

Biology and Medicine Division: Annual report 1986

International Nuclear Information System (INIS)

1987-04-01

The Biology and Medicine Division continues to make important contributions in scientific areas in which it has a long-established leadership role. For 50 years the Division has pioneered in the application of radioisotopes and charged particles to biology and medicine. There is a growing emphasis on cellular and molecular applications in the work of all the Division's research groups. The powerful tools of genetic engineering, the use of recombinant products, the analytical application of DNA probes, and the use of restriction fragment length polymorphic DNA are described and proposed for increasing use in the future

Biology and Medicine Division: Annual report 1986

Energy Technology Data Exchange (ETDEWEB)

1987-04-01

The Biology and Medicine Division continues to make important contributions in scientific areas in which it has a long-established leadership role. For 50 years the Division has pioneered in the application of radioisotopes and charged particles to biology and medicine. There is a growing emphasis on cellular and molecular applications in the work of all the Division's research groups. The powerful tools of genetic engineering, the use of recombinant products, the analytical application of DNA probes, and the use of restriction fragment length polymorphic DNA are described and proposed for increasing use in the future.

Mapping Urban Social Divisions

Directory of Open Access Journals (Sweden)

Susan Ball

2010-05-01

Full Text Available Against the background of increased levels of interest in space and images beyond the field of geography, this article (re- introduces earlier work on the semiotics of maps undertaken by geographers in the 1960s. The data limitations, purpose and cultural context in which a user interprets a map's codes and conventions are highlighted in this work, which remains relevant to the interpretation of maps—new and old—forty years later. By means of drawing on geography's contribution to the semiotics of maps, the article goes on to examine the concept of urban social divisions as represented in map images. Using a small number of map images, including two of the most widely known maps of urban social division in Europe and North America, the roles of context, data and purpose in the production and interpretation of maps are discussed. By presenting the examples chronologically the article shows that although advances in data collection and manipulation have allowed researchers to combine different social variables in maps of social division, and to interact with map images, work by geographers on the semiotics of maps is no less relevant today than when it was first proposed forty years ago. URN: urn:nbn:de:0114-fqs1002372

Nuclear Chemistry Division annual report FY83

Energy Technology Data Exchange (ETDEWEB)

Struble, G. (ed.)

1983-01-01

The purpose of the annual reports of the Nuclear Chemistry Division is to provide a timely summary of research activities pursued by members of the Division during the preceding year. Throughout, details are kept to a minimum; readers desiring additional information are encouraged to read the referenced documents or contact the authors. The Introduction presents an overview of the Division's scientific and technical programs. Next is a section of short articles describing recent upgrades of the Division's major facilities, followed by sections highlighting scientific and technical advances. These are grouped under the following sections: nuclear explosives diagnostics; geochemistry and environmental sciences; safeguards technology and radiation effect; and supporting fundamental science. A brief overview introduces each section. Reports on research supported by a particular program are generally grouped together in the same section. The last section lists the scientific, administrative, and technical staff in the Division, along with visitors, consultants, and postdoctoral fellows. It also contains a list of recent publications and presentations. Some contributions to the annual report are classified and only their abstracts are included in this unclassified portion of the report (UCAR-10062-83/1); the full article appears in the classified portion (UCAR-10062-83/2).

Use of Time-Frequency Analysis and Neural Networks for Mode Identification in a Wireless Software-Defined Radio Approach

Directory of Open Access Journals (Sweden)

Matteo Gandetto

2004-09-01

Full Text Available The use of time-frequency distributions is proposed as a nonlinear signal processing technique that is combined with a pattern recognition approach to identify superimposed transmission modes in a reconfigurable wireless terminal based on software-defined radio techniques. In particular, a software-defined radio receiver is described aiming at the identification of two coexistent communication modes: frequency hopping code division multiple access and direct sequence code division multiple access. As a case study, two standards, based on the previous modes and operating in the same band (industrial, scientific, and medical, are considered: IEEE WLAN 802.11b (direct sequence and Bluetooth (frequency hopping. Neural classifiers are used to obtain identification results. A comparison between two different neural classifiers is made in terms of relative error frequency.

Simulation and measurement of optical access network with different types of optical-fiber amplifiers

Science.gov (United States)

Latal, Jan; Vogl, Jan; Koudelka, Petr; Vitasek, Jan; Siska, Petr; Liner, Andrej; Papes, Martin; Vasinek, Vladimir

2012-01-01

The optical access networks are nowadays swiftly developing in the telecommunications field. These networks can provide higher data transfer rates, and have great potential to the future in terms of transmission possibilities. Many local internet providers responded to these facts and began gradually installing optical access networks into their originally built networks, mostly based on wireless communication. This allowed enlargement of possibilities for end-users in terms of high data rates and also new services such as Triple play, IPTV (Internet Protocol television) etc. However, with this expansion and building-up is also related the potential of reach in case of these networks. Big cities, such as Prague, Brno, Ostrava or Olomouc cannot be simply covered, because of their sizes and also because of their internal regulations given by various organizations in each city. Standard logical and also physical reach of EPON (IEEE 802.3ah - Ethernet Passive Optical Network) optical access network is about 20 km. However, for networks based on Wavelength Division Multiplex the reach can be up to 80 km, if the optical-fiber amplifier is inserted into the network. This article deals with simulation of different types of amplifiers for WDM-PON (Wavelength Division Multiplexing-Passive Optical Network) network in software application Optiwave OptiSystem and than are the values from the application and from real measurement compared.

Reactor Engineering Division annual report

International Nuclear Information System (INIS)

1978-10-01

Research activities in the Division of Reactor Engineering in fiscal 1977 are described. Works of the Division are development of multi-purpose Very High Temperature Gas Cooled Reactor, fusion reactor engineering, and development of Liquid Metal Fast Breeder Reactor for Power Reactor and Nuclear Fuel Development Corporation. Contents of the report are nuclear data and group constants, theoretical method and code development, integral experiment and analysis, shielding, heat transfer and fluid dynamics, reactor and nuclear instrumentation, dynamics analysis and control method development, fusion reactor technology, and Committee on Reactor Physics. (Author)

Energy Technology Division research summary 1997

International Nuclear Information System (INIS)

1997-01-01

The Energy Technology Division provides materials and engineering technology support to a wide range of programs important to the US Department of Energy. As shown on the preceding page, the Division is organized into ten sections, five with concentrations in the materials area and five in engineering technology. Materials expertise includes fabrication, mechanical properties, corrosion, friction and lubrication, and irradiation effects. Our major engineering strengths are in heat and mass flow, sensors and instrumentation, nondestructive testing, transportation, and electromechanics and superconductivity applications. The Division Safety Coordinator, Environmental Compliance Officers, Quality Assurance Representative, Financial Administrator, and Communication Coordinator report directly to the Division Director. The Division Director is personally responsible for cultural diversity and is a member of the Laboratory-wide Cultural Diversity Advisory Committee. The Division's capabilities are generally applied to issues associated with energy production, transportation, utilization or conservation, or with environmental issues linked to energy. As shown in the organization chart on the next page, the Division reports administratively to the Associate Laboratory Director (ALD) for Energy and Environmental Science and Technology (EEST) through the General Manager for Environmental and Industrial Technologies. While most of our programs are under the purview of the EEST ALD, we also have had programs funded under every one of the ALDs. Some of our research in superconductivity is funded through the Physical Research Program ALD. We also continue to work on a number of nuclear-energy-related programs under the ALD for Engineering Research. Detailed descriptions of our programs on a section-by-section basis are provided in the remainder of this book. This Overview highlights some major trends. Research related to the operational safety of commercial light water nuclear

Energy Technology Division research summary 1997.

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-10-21

The Energy Technology Division provides materials and engineering technology support to a wide range of programs important to the US Department of Energy. As shown on the preceding page, the Division is organized into ten sections, five with concentrations in the materials area and five in engineering technology. Materials expertise includes fabrication, mechanical properties, corrosion, friction and lubrication, and irradiation effects. Our major engineering strengths are in heat and mass flow, sensors and instrumentation, nondestructive testing, transportation, and electromechanics and superconductivity applications. The Division Safety Coordinator, Environmental Compliance Officers, Quality Assurance Representative, Financial Administrator, and Communication Coordinator report directly to the Division Director. The Division Director is personally responsible for cultural diversity and is a member of the Laboratory-wide Cultural Diversity Advisory Committee. The Division's capabilities are generally applied to issues associated with energy production, transportation, utilization or conservation, or with environmental issues linked to energy. As shown in the organization chart on the next page, the Division reports administratively to the Associate Laboratory Director (ALD) for Energy and Environmental Science and Technology (EEST) through the General Manager for Environmental and Industrial Technologies. While most of our programs are under the purview of the EEST ALD, we also have had programs funded under every one of the ALDs. Some of our research in superconductivity is funded through the Physical Research Program ALD. We also continue to work on a number of nuclear-energy-related programs under the ALD for Engineering Research. Detailed descriptions of our programs on a section-by-section basis are provided in the remainder of this book. This Overview highlights some major trends. Research related to the operational safety of commercial light water

Division V: Commission 42: Close Binaries

Science.gov (United States)

Ribas, Ignasi; Richards, Mercedes T.; Rucinski, Slavek; Bradstreet, David H.; Harmanec, Petr; Kaluzny, Janusz; Mikolajewska, Joanna; Munari, Ulisse; Niarchos, Panagiotis; Olah, Katalin; Pribulla, Theodor; Scarfe, Colin D.; Torres, Guillermo

2015-08-01

Commission 42 (C42) co-organized, together with Commission 27 (C27) and Division V (Div V) as a whole, a full day of science and business sessions that were held on 24 August 2012. The program included time slots for discussion of business matters related to Div V, C27 and C42, and two sessions of 2 hours each devoted to science talks of interest to both C42 and C27. In addition, we had a joint session between Div IV and Div V motivated by the proposal to reformulate the division structure of the IAU and the possible merger of the two divisions into a new Div G. The current report gives an account of the matters discussed during the business session of C42.

Wireless and wireline service convergence in next generation optical access networks - the FP7 WISCON project

DEFF Research Database (Denmark)

Vegas Olmos, Juan José; Pang, Xiaodan; Lebedev, Alexander

2014-01-01

The next generation of information technology demands both high capacity and mobility for applications such as high speed wireless access capable of supporting broadband services. The transport of wireless and wireline signals is converging into a common telecommunication infrastructure....... In this paper, we will present the Marie Curie Framework Program 7 project “Wireless and wireline service convergence in next generation optical access networks” (WISCON), which focuses on the conception and study of novel architectures for wavelength-division-multiplexing (WDM) optical multi-modulation format...

Theoretical Division annual report, FY 1975. [LASL

Energy Technology Data Exchange (ETDEWEB)

Carruthers, P.A.

1976-02-01

This report presents an overview of the activities in the Theoretical Division and a summary of research highlights during FY 1975. It is intended to inform a wide audience about the theoretical work of the LASL and, therefore, contains introductory material which places recent advances in a broader context. The report is organized into two special interest reports: reactor safety research and the Advanced Research Committee, and 11 reports from the T-Division group leaders on the work of their respective groups. Main interests and responsibilities are outlined including the relationship of the group's work to the work of other T-Division groups and other divisions at the Laboratory. The description of research highlights for FY 1975 explains in a fairly simple, straightforward manner the major recent advances and their significance. Each group report is followed by a publication list for FY 1975 (330 references) and a list of talks given outside the Laboratory (140 references). 29 figures. (auth)

Case studies of natural resource access in Jharkhand, India

DEFF Research Database (Denmark)

Sareen, Siddharth

This policy brief illustrates that decentralisation can only effectively support residents’ access to natural resources if it both resolves policy overlaps at multiple levels to bring about inclusive and equitable access and aligns policies with ground realities for specific natural resources....

Traffic-Adaptive, Flow-Specific Medium Access for Wireless Networks

Science.gov (United States)

2009-09-01

51 b. Carrier Sense Multiple Access (CSMA).................................52 c. MACA and MACAW...Figure 17. Comparison of collision avoidance techniques proposed in MACA , MACAW, and MACA -BI (From [132...low power listening lrd ......................long range dependent MAC .................medium access control MACA

Applications Frontpage In Designing A Web Site Marketing Division Of Education Institutions In Indonesia Branch American Kebon Jeruk

OpenAIRE

Wiwiek Pujiningsih; Jalinas SKom MM Jalinas SKom MM

2002-01-01

Marketing Division in each company at the forefront in introducing products to thepublic and marketing these products. Media marketing can through print andelectronic media. Print media for example newspapers, brochures and pamphlets.Electronic media, through television and radio.We have a faster delivery of media and can be accessed by everyone, namely throughthe Internet media. Give through the Internet media can be done by making thehomepage. With a homepage we can make a company profile w...

Nuclear Science Division, 1995--1996 annual report

International Nuclear Information System (INIS)

Poskanzer, A.M.

1997-02-01

This report describes the activities of the Nuclear Science Division (NSD) for the two-year period, January 1, 1995 to January 1, 1997. This was a time of major accomplishments for all research programs in the Division-many of which are highlighted in the reports of this document

Nuclear Science Division, 1995--1996 annual report

Energy Technology Data Exchange (ETDEWEB)

Poskanzer, A.M. [ed.

1997-02-01

This report describes the activities of the Nuclear Science Division (NSD) for the two-year period, January 1, 1995 to January 1, 1997. This was a time of major accomplishments for all research programs in the Division-many of which are highlighted in the reports of this document.

Safety and Health Division achievements during 40 years

International Nuclear Information System (INIS)

Noriah Mod Ali

2012-01-01

During her speech, presenter outlined several issues regarding on establishment of Safety and Health Division since 40 years. This division contain of 3 sub unit; Physical Safety Group, Medical Physic Group and Non-ionizing Radiation group (NIR). The objectives of this division to implement R and D activities and services regarding safety and radiological health also non-radiological to ensure public safety, environment and asset suit with obligations established by authorities, IAEA standards and regulations.(author)

Earth Sciences Division, collected abstracts, 1978

International Nuclear Information System (INIS)

Taasevigen, D.K.; Henry, A.L.; Madsen, S.K.

1979-01-01

Abstracts of papers, internal reports, and talks presented during 1978 at national and international meetings by members of the Earth Sciences Division of the Lawrence Livermore Laboratory are compiled. The arrangement is alphabetical (by author). For any given report, a bibliographic reference appears under the name of each coauthor. A topical index at the end provides useful cross references, while indicating major areas of research interest in the Earth Sciences Division

Weapons Experiments Division Explosives Operations Overview

Energy Technology Data Exchange (ETDEWEB)

Laintz, Kenneth E. [Los Alamos National Laboratory

2012-06-19

Presentation covers WX Division programmatic operations with a focus on JOWOG-9 interests. A brief look at DARHT is followed by a high level overview of explosives research activities currently being conducted within in the experimental groups of WX-Division. Presentation covers more emphasis of activities and facilities at TA-9 as these efforts have been more traditionally aligned with ongoing collaborative explosive exchanges covered under JOWOG-9.

GEOM/GEOM[a]/1/ queue with late arrival system with delayed access and delayed multiple working vacations

Directory of Open Access Journals (Sweden)

Cheng Jiang

2014-01-01

Full Text Available This paper considers a discrete-time bulk-service queue with infinite buffer space and delay multiple working vacations. Considering a late arrival system with delayed access (LAS-AD, it is assumed that the inter-arrival times, service times, vacation times are all geometrically distributed. The server does not take a vacation immediately at service complete epoch but keeps idle period. According to a bulk-service rule, at least one customer is needed to start a service with a maximum serving capacity 'a'. Using probability analysis method and displacement operator method, the queue length and the probability generating function of waiting time at pre-arrival epochs are obtained. Furthermore, the outside observer’s observation epoch queue length distributions are given. Finally, computational examples with numerical results in the form of graphs and tables are discussed.

Access to and Usage of Information among Rural Communities: a Case Study of Kilosa District Morogoro Region in Tanzania

Directory of Open Access Journals (Sweden)

Wulystan Pius Mtega

2012-05-01

Full Text Available The study investigated how rural communities in Kilosa District of Morogoro region in Tanzania accessed and used information. Specifically the study identified the information needs of rural people; determined the factors influencing the choice of information sources; and the appropriateness of the information sources basing on usefulness and preference. Three divisions were involved in the study area, choice of the study area was based on the availability of multiple information sources/channels information seekers could consulted. Simple random sampling technique was employed in selecting villages to be investigated and respondents to be interviewed. Findings showed that almost all people needed information of all types. Most of the information needed related to day to day problems. Information was accessed mainly through radio, television sets, newspapers and magazines, and also through cell phones and face to face communication. Choice of information sources was influenced by the respondents’ level of education, income, sex, age, occupation and distance from the information seeker’s residence to the information sources. Findings showed further that people accessed and used information for solving day to day problems and for leisure purposes. The study recommends that it is important to have frequent rural information needs assessments before providing information services to rural areas. Information providers should repackage information in appropriate forms suitable for rural communities. Moreover, radio and television stations should have enough rural related programmes which should be broadcasted during appropriate time.

Integrated Optical Content Addressable Memories (CAM and Optical Random Access Memories (RAM for Ultra-Fast Address Look-Up Operations

Directory of Open Access Journals (Sweden)

Christos Vagionas

2017-07-01

Full Text Available Electronic Content Addressable Memories (CAM implement Address Look-Up (AL table functionalities of network routers; however, they typically operate in the MHz regime, turning AL into a critical network bottleneck. In this communication, we demonstrate the first steps towards developing optical CAM alternatives to enable a re-engineering of AL memories. Firstly, we report on the photonic integration of Semiconductor Optical Amplifier-Mach Zehnder Interferometer (SOA-MZI-based optical Flip-Flop and Random Access Memories on a monolithic InP platform, capable of storing the binary prefix-address data-bits and the outgoing port information for next hop routing, respectively. Subsequently the first optical Binary CAM cell (B-CAM is experimentally demonstrated, comprising an InP Flip-Flop and a SOA-MZI Exclusive OR (XOR gate for fast search operations through an XOR-based bit comparison, yielding an error-free 10 Gb/s operation. This is later extended via physical layer simulations in an optical Ternary-CAM (T-CAM cell and a 4-bit Matchline (ML configuration, supporting a third state of the “logical X” value towards wildcard bits of network subnet masks. The proposed functional CAM and Random Access Memories (RAM sub-circuits may facilitate light-based Address Look-Up tables supporting search operations at 10 Gb/s and beyond, paving the way towards minimizing the disparity with the frantic optical transmission linerates, and fast re-configurability through multiple simultaneous Wavelength Division Multiplexed (WDM memory access requests.

Laser and Plasma Technology Division annual report 1993

International Nuclear Information System (INIS)

Venkatramani, N.; Verma, R.L.

1994-01-01

This report describes the activities of the Laser and Plasma Technology Division during the year 1993. This Division is engaged in the research and development of high power beams namely laser, plasma and electron beams, which are characterized by high power density, normally in excess of 1 kW/mm 2 . Laser and Plasma Technology Division has strived to establish indigenous capability to cater to the requirements of the Department of Atomic Energy. The broad programme objectives of the Division are : (1) Development and technology readiness studies of laser, plasma and electron beam devices, (2) Studies on related physical phenomena with a view to gain better understanding of the devices, and (3) Improvements in technology and exploration of new areas. This report covers the activities of the Division during 1993 and describes how successfully the objectives have been met. The activities described in the report are diverse in nature. The report has been compiled from individual reports of various groups/sections with marginal editing. (author). refs., tabs., figs

Laser and Plasma Technology Division annual report 1993

Energy Technology Data Exchange (ETDEWEB)

Venkatramani, N; Verma, R L [eds.; Bhabha Atomic Research Centre, Bombay (India). Laser and Plasma Technology Div.

1994-12-31

This report describes the activities of the Laser and Plasma Technology Division during the year 1993. This Division is engaged in the research and development of high power beams namely laser, plasma and electron beams, which are characterized by high power density, normally in excess of 1 kW/mm{sup 2}. Laser and Plasma Technology Division has strived to establish indigenous capability to cater to the requirements of the Department of Atomic Energy. The broad programme objectives of the Division are : (1) Development and technology readiness studies of laser, plasma and electron beam devices, (2) Studies on related physical phenomena with a view to gain better understanding of the devices, and (3) Improvements in technology and exploration of new areas. This report covers the activities of the Division during 1993 and describes how successfully the objectives have been met. The activities described in the report are diverse in nature. The report has been compiled from individual reports of various groups/sections with marginal editing. (author). refs., tabs., figs.

Admission Control of Integrated Voice and Data CDMA／TDD System Considering Asymmetric Traffic and Power Limit

Institute of Scientific and Technical Information of China (English)

CAOYanbo; ZHOUBin; LIChengshu

2004-01-01

In this paper, we research an admission control scheme of integrated voice and data CDMA/TDD (Code division multiple access/Time division duplex) system considering asymmetric traffic and power limit. A new user can access the system only if the outage probabilities it experiences on the uplink and downlink time slots are below a threshold value. Based on the power limit the results show the voice and data blocking probabilities under different cell coverage~ arrival rates and various uplink/downlink time slot allocation patterns. Furthermore, multicode and multislot schemes are also evaluated under the presented admission control scheme.

Get the right access rights!

CERN Multimedia

Rosaria Marraffino

2015-01-01

On 11 May, a major change concerning the requirements to access the CERN beam facilities was put in place and implemented in ADaMS in order to reduce the number of courses that people who need access to multiple installations have to follow. This revision includes dedicated safety training courses that replace, in particular, the “Safety during LS1” e-learning course, which is now to be considered obsolete.   CERN’s Access Distribution and Management System (ADaMS). As of 11 May, an important improvement was implemented in ADaMS (CERN’s Access Distribution and Management System) regarding the requisites to access safety zones. This change is closely related to the introduction of a generic e-learning course ("CERN Beam Facilities") covering the common risks and systems present in CERN's beam facilities. Two e-learning courses are no longer valid, nor available on the SIR (Safety Information Registration) catalogue: the &ld...

DNR Division of Parks and Trails District Boundaries

Data.gov (United States)

Minnesota Department of Natural Resources — This data shows the DNR Division of Parks and Trails District Boundaries as of May 2010. The boundaries were created by the Division Leadership Team. Boundaries are...

Energy Technology Division research summary -- 1994

International Nuclear Information System (INIS)

1994-09-01

Research funded primarily by the NRC is directed toward assessing the roles of cyclic fatigue, intergranular stress corrosion cracking, and irradiation-assisted stress corrosion cracking on failures in light water reactor (LWR) piping systems, pressure vessels, and various core components. In support of the fast reactor program, the Division has responsibility for fuel-performance modeling and irradiation testing. The Division has major responsibilities in several design areas of the proposed International Thermonuclear Experimental Reactor (ITER). The Division supports the DOE in ensuring safe shipment of nuclear materials by providing extensive review of the Safety Analysis Reports for Packaging (SARPs). Finally, in the nuclear area they are investigating the safe disposal of spent fuel and waste. In work funded by DOE's Energy Efficiency and Renewable Energy, the high-temperature superconductivity program continues to be a major focal point for industrial interactions. Coatings and lubricants developed in the division's Tribology Section are intended for use in transportation systems of the future. Continuous fiber ceramic composites are being developed for high-performance heat engines. Nondestructive testing techniques are being developed to evaluate fiber distribution and to detect flaws. A wide variety of coatings for corrosion protection of metal alloys are being studied. These can increase lifetimes significant in a wide variety of coal combustion and gasification environments

Analytical Evaluation of the Performance of Proportional Fair Scheduling in OFDMA-Based Wireless Systems

Directory of Open Access Journals (Sweden)

Mohamed H. Ahmed

2012-01-01

Full Text Available This paper provides an analytical evaluation of the performance of proportional fair (PF scheduling in Orthogonal Frequency-Division Multiple Access (OFDMA wireless systems. OFDMA represents a promising multiple access scheme for transmission over wireless channels, as it combines the orthogonal frequency division multiplexing (OFDM modulation and subcarrier allocation. On the other hand, the PF scheduling is an efficient resource allocation scheme with good fairness characteristics. Consequently, OFDMA with PF scheduling represents an attractive solution to deliver high data rate services to multiple users simultaneously with a high degree of fairness. We investigate a two-dimensional (time slot and frequency subcarrier PF scheduling algorithm for OFDMA systems and evaluate its performance analytically and by simulations. We derive approximate closed-form expressions for the average throughput, throughput fairness index, and packet delay. Computer simulations are used for verification. The analytical results agree well with the results from simulations, which show the good accuracy of the analytical expressions.

Tag-to-Tag Interference Suppression Technique Based on Time Division for RFID

Directory of Open Access Journals (Sweden)

Grishma Khadka

2017-01-01

Full Text Available Radio-frequency identification (RFID is a tracking technology that enables immediate automatic object identification and rapid data sharing for a wide variety of modern applications using radio waves for data transmission from a tag to a reader. RFID is already well established in technical areas, and many companies have developed corresponding standards and measurement techniques. In the construction industry, effective monitoring of materials and equipment is an important task, and RFID helps to improve monitoring and controlling capabilities, in addition to enabling automation for construction projects. However, on construction sites, there are many tagged objects and multiple RFID tags that may interfere with each other’s communications. This reduces the reliability and efficiency of the RFID system. In this paper, we propose an anti-collision algorithm for communication between multiple tags and a reader. In order to suppress interference signals from multiple neighboring tags, the proposed algorithm employs the time-division (TD technique, where tags in the interrogation zone are assigned a specific time slot so that at every instance in time, a reader communicates with tags using the specific time slot. We present representative computer simulation examples to illustrate the performance of the proposed anti-collision technique for multiple RFID tags.

Solid State Division

International Nuclear Information System (INIS)

Green, P.H.; Watson, D.M.

1989-08-01

This report contains brief discussions on work done in the Solid State Division of Oak Ridge National Laboratory. The topics covered are: Theoretical Solid State Physics; Neutron scattering; Physical properties of materials; The synthesis and characterization of materials; Ion beam and laser processing; and Structure of solids and surfaces

Power-efficient method for IM-DD optical transmission of multiple OFDM signals.

Science.gov (United States)

Effenberger, Frank; Liu, Xiang

2015-05-18

We propose a power-efficient method for transmitting multiple frequency-division multiplexed (FDM) orthogonal frequency-division multiplexing (OFDM) signals in intensity-modulation direct-detection (IM-DD) optical systems. This method is based on quadratic soft clipping in combination with odd-only channel mapping. We show, both analytically and experimentally, that the proposed approach is capable of improving the power efficiency by about 3 dB as compared to conventional FDM OFDM signals under practical bias conditions, making it a viable solution in applications such as optical fiber-wireless integrated systems where both IM-DD optical transmission and OFDM signaling are important.