Fault-tolerance performance evaluation of fieldbus for NPCS network of KNGR

International Nuclear Information System (INIS)

Jung, Hyun Gi

1999-02-01

In contrast with conventional fieldbus researches which are focused merely on real time performance, this study aims to evaluate the real-time performance of the communication system including fault-tolerant mechanisms. Maintaining performance in presence of recoverable faults is very important because the communication network will be applied to next generation NPP(Nuclear Power Plant). In order to guarantee the performance of NPP communication network, the time characteristics of the target system in presence of recoverable fault should be investigated. If the time characteristics meet the requirements of the system, the faults will be recovered by fieldbus recovery mechanisms and the system will be safe. If the time characteristics can not meet the requirements, the faults in the fieldbus can propagate to system failure. In this study, for the purpose of investigating the time characteristics of fieldbus, the recoverable faults are classified and then the formulas which represent delays including recovery mechanisms and the simulation model are developed. In order to validate the proposed approach, the simulation model is applied to the Korea Next Generation Reactor (KNGR) NSSS Process Control System (NPCS). The results of the simulation provide reasonable delay characteristics of the fault cases with recovery mechanisms. Using the outcome of the simulation and the system requirements, we also can calculate the failure propagation probability from fieldbus to outer system

IMPACT OF SOCIAL NETWORK STRUCTURE ON EMPLOYEE PERFORMANCE: A COMPARATIVE STUDY

OpenAIRE

Claudio Lira Meirelles; Thais Cereda Ravasi; Fabio Teixeira Arten; João Paulo Lara Siqueira

2013-01-01

This research sought to understand the relationship between the position of the central actor and the performance of a network, checking the influence of the central actor's performance over other actors. Among the specific objectives, we sought to describe the transactional content, the nature of the connections and the structural characteristics of the network. Data were collected through a questionnaire and analyzed with the help of software UCINET 6.0 and Excel. The results suggest tha...

High-Performance Networking

CERN Multimedia

CERN. Geneva

2003-01-01

The series will start with an historical introduction about what people saw as high performance message communication in their time and how that developed to the now to day known "standard computer network communication". It will be followed by a far more technical part that uses the High Performance Computer Network standards of the 90's, with 1 Gbit/sec systems as introduction for an in depth explanation of the three new 10 Gbit/s network and interconnect technology standards that exist already or emerge. If necessary for a good understanding some sidesteps will be included to explain important protocols as well as some necessary details of concerned Wide Area Network (WAN) standards details including some basics of wavelength multiplexing (DWDM). Some remarks will be made concerning the rapid expanding applications of networked storage.

Integrated System for Performance Monitoring of ATLAS TDAQ Network

CERN Document Server

Savu, D; The ATLAS collaboration; Martin, B; Sjoen, R; Batraneanu, S; Stancu, S

2010-01-01

The ATLAS TDAQ Network consists of three separate networks spanning four levels of the experimental building. Over 200 edge switches and 5 multi-blade chassis routers are used to interconnect 2000 processors, adding up to more than 7000 high speed interfaces. In order to substantially speed-up ad-hoc and post mortem analysis, a scalable, yet flexible, integrated system for monitoring both network statistics and environmental conditions, processor parameters and data taking characteristics was required. For successful up-to-the-minute monitoring, information from many SNMP compliant devices, independent databases and custom APIs was gathered, stored and displayed in an optimal way. Easy navigation and compact aggregation of multiple data sources were the main requirements; characteristics not found in any of the tested products, either open-source or commercial. This paper describes how performance, scalability and display issues were addressed and what challenges the project faced during development and deplo...

Competitive Learning Neural Network Ensemble Weighted by Predicted Performance

Science.gov (United States)

Ye, Qiang

2010-01-01

Ensemble approaches have been shown to enhance classification by combining the outputs from a set of voting classifiers. Diversity in error patterns among base classifiers promotes ensemble performance. Multi-task learning is an important characteristic for Neural Network classifiers. Introducing a secondary output unit that receives different…

Integrated healthcare networks' performance: a growth curve modeling approach.

Science.gov (United States)

Wan, Thomas T H; Wang, Bill B L

2003-05-01

This study examines the effects of integration on the performance ratings of the top 100 integrated healthcare networks (IHNs) in the United States. A strategic-contingency theory is used to identify the relationship of IHNs' performance to their structural and operational characteristics and integration strategies. To create a database for the panel study, the top 100 IHNs selected by the SMG Marketing Group in 1998 were followed up in 1999 and 2000. The data were merged with the Dorenfest data on information system integration. A growth curve model was developed and validated by the Mplus statistical program. Factors influencing the top 100 IHNs' performance in 1998 and their subsequent rankings in the consecutive years were analyzed. IHNs' initial performance scores were positively influenced by network size, number of affiliated physicians and profit margin, and were negatively associated with average length of stay and technical efficiency. The continuing high performance, judged by maintaining higher performance scores, tended to be enhanced by the use of more managerial or executive decision-support systems. Future studies should include time-varying operational indicators to serve as predictors of network performance.

Network survivability performance (computer diskette)

Science.gov (United States)

1993-11-01

File characteristics: Data file; 1 file. Physical description: 1 computer diskette; 3 1/2 in.; high density; 2.0MB. System requirements: Mac; Word. This technical report has been developed to address the survivability of telecommunications networks including services. It responds to the need for a common understanding of, and assessment techniques for network survivability, availability, integrity, and reliability. It provides a basis for designing and operating telecommunication networks to user expectations for network survivability.

Performance Analysis of RF-FSO Multi-Hop Networks

KAUST Repository

Makki, Behrooz

2017-05-12

We study the performance of multi-hop networks composed of millimeter wave (MMW)-based radio frequency (RF) and free-space optical (FSO) links. The results are obtained in the cases with and without hybrid automatic repeat request (HARQ). Taking the MMW characteristics of the RF links into account, we derive closed-form expressions for the network outage probability. We also evaluate the effect of various parameters such as power amplifiers efficiency, number of antennas as well as different coherence times of the RF and the FSO links on the system performance. Finally, we present mappings between the performance of RF- FSO multi-hop networks and the ones using only the RF- or the FSO-based communication, in the sense that with appropriate parameter settings the same outage probability is achieved in these setups. The results show the efficiency of the RF-FSO setups in different conditions. Moreover, the HARQ can effectively improve the outage probability/energy efficiency, and compensate the effect of hardware impairments in RF-FSO networks. For common parameter settings of the RF-FSO dual- hop networks, outage probability 10^{-4} and code rate 3 nats-per-channel-use, the implementation of HARQ with a maximum of 2 and 3 retransmissions reduces the required power, compared to the cases with no HARQ, by 13 and 17 dB, respectively.

Diagnosing Anomalous Network Performance with Confidence

Energy Technology Data Exchange (ETDEWEB)

Settlemyer, Bradley W [ORNL; Hodson, Stephen W [ORNL; Kuehn, Jeffery A [ORNL; Poole, Stephen W [ORNL

2011-04-01

Variability in network performance is a major obstacle in effectively analyzing the throughput of modern high performance computer systems. High performance interconnec- tion networks offer excellent best-case network latencies; how- ever, highly parallel applications running on parallel machines typically require consistently high levels of performance to adequately leverage the massive amounts of available computing power. Performance analysts have usually quantified network performance using traditional summary statistics that assume the observational data is sampled from a normal distribution. In our examinations of network performance, we have found this method of analysis often provides too little data to under- stand anomalous network performance. Our tool, Confidence, instead uses an empirically derived probability distribution to characterize network performance. In this paper we describe several instances where the Confidence toolkit allowed us to understand and diagnose network performance anomalies that we could not adequately explore with the simple summary statis- tics provided by traditional measurement tools. In particular, we examine a multi-modal performance scenario encountered with an Infiniband interconnection network and we explore the performance repeatability on the custom Cray SeaStar2 interconnection network after a set of software and driver updates.

The Application of Social Characteristic and L1 Optimization in the Error Correction for Network Coding in Wireless Sensor Networks.

Science.gov (United States)

Zhang, Guangzhi; Cai, Shaobin; Xiong, Naixue

2018-02-03

One of the remarkable challenges about Wireless Sensor Networks (WSN) is how to transfer the collected data efficiently due to energy limitation of sensor nodes. Network coding will increase network throughput of WSN dramatically due to the broadcast nature of WSN. However, the network coding usually propagates a single original error over the whole network. Due to the special property of error propagation in network coding, most of error correction methods cannot correct more than C /2 corrupted errors where C is the max flow min cut of the network. To maximize the effectiveness of network coding applied in WSN, a new error-correcting mechanism to confront the propagated error is urgently needed. Based on the social network characteristic inherent in WSN and L1 optimization, we propose a novel scheme which successfully corrects more than C /2 corrupted errors. What is more, even if the error occurs on all the links of the network, our scheme also can correct errors successfully. With introducing a secret channel and a specially designed matrix which can trap some errors, we improve John and Yi's model so that it can correct the propagated errors in network coding which usually pollute exactly 100% of the received messages. Taking advantage of the social characteristic inherent in WSN, we propose a new distributed approach that establishes reputation-based trust among sensor nodes in order to identify the informative upstream sensor nodes. With referred theory of social networks, the informative relay nodes are selected and marked with high trust value. The two methods of L1 optimization and utilizing social characteristic coordinate with each other, and can correct the propagated error whose fraction is even exactly 100% in WSN where network coding is performed. The effectiveness of the error correction scheme is validated through simulation experiments.

Copercolating Networks: An Approach for Realizing High-Performance Transparent Conductors using Multicomponent Nanostructured Networks

Directory of Open Access Journals (Sweden)

Das Suprem R.

2016-06-01

Full Text Available Although transparent conductive oxides such as indium tin oxide (ITO are widely employed as transparent conducting electrodes (TCEs for applications such as touch screens and displays, new nanostructured TCEs are of interest for future applications, including emerging transparent and flexible electronics. A number of twodimensional networks of nanostructured elements have been reported, including metallic nanowire networks consisting of silver nanowires, metallic carbon nanotubes (m-CNTs, copper nanowires or gold nanowires, and metallic mesh structures. In these single-component systems, it has generally been difficult to achieve sheet resistances that are comparable to ITO at a given broadband optical transparency. A relatively new third category of TCEs consisting of networks of 1D-1D and 1D-2D nanocomposites (such as silver nanowires and CNTs, silver nanowires and polycrystalline graphene, silver nanowires and reduced graphene oxide have demonstrated TCE performance comparable to, or better than, ITO. In such hybrid networks, copercolation between the two components can lead to relatively low sheet resistances at nanowire densities corresponding to high optical transmittance. This review provides an overview of reported hybrid networks, including a comparison of the performance regimes achievable with those of ITO and single-component nanostructured networks. The performance is compared to that expected from bulk thin films and analyzed in terms of the copercolation model. In addition, performance characteristics relevant for flexible and transparent applications are discussed. The new TCEs are promising, but significant work must be done to ensure earth abundance, stability, and reliability so that they can eventually replace traditional ITO-based transparent conductors.

Evolution Characteristics of the Network Core in the Facebook

OpenAIRE

Liu, Jian-Guo; Ren, Zhuo-Ming; Guo, Qiang; Chen, Duan-Bing

2014-01-01

Statistical properties of the static networks have been extensively studied. However, online social networks are evolving dynamically, understanding the evolving characteristics of the core is one of major concerns in online social networks. In this paper, we empirically investigate the evolving characteristics of the Facebook core. Firstly, we separate the Facebook-link(FL) and Facebook-wall(FW) datasets into 28 snapshots in terms of timestamps. By employing the k-core decomposition method t...

The Effects of Nonperforming Loans on Dynamic Network Bank Performance

Directory of Open Access Journals (Sweden)

Day-Yang Liu

2017-01-01

Full Text Available This paper is to explore the relationship between banks’ performance and their nonperforming loans (NPLs. The banks’ performance through a network production process structure with NPLs is developed. With increasing NPLs in recent years, the quality of lending assets is a key significant and influencing factor for banks’ operational risk. The research methodology is to integrate the radial and nonradial measures of efficiency into the network production process framework with NPLs; this study utilizes network epsilon-based measure model to evaluate the banking industry performance. In addition, the key characteristics of the bank industry including those of financial holding companies and privatized government banks are needed to be figured out and to provide insight into what causes imperfectly competitive conditions for some banks. The results demonstrate that the banking sector grew consistently in three aspects of operation: operating performance, profitability performance, and risk management in the last five years of the subject period. These results showed that the overall banking sector was capable of pursuing growth in both operations and profits while accounting for risk management. The potential applications and strengths of network data envelopment analysis in assessing financial organizations are also highlighted.

Social network characteristics associated with health promoting behaviors among Latinos.

Science.gov (United States)

Marquez, Becky; Elder, John P; Arredondo, Elva M; Madanat, Hala; Ji, Ming; Ayala, Guadalupe X

2014-06-01

This study examined the relationship between social network characteristics and health promoting behaviors (having a routine medical check-up, consuming no alcohol, consuming no fast food, and meeting recommendations for leisure-time physical activity and sleep duration) among Latinos to identify potential targets for behavioral interventions. Personal network characteristics and health behavior data were collected from a community sample of 393 adult Latinos (73% women) in San Diego County, California. Network characteristics consisted of size and composition. Network size was calculated by the number of alters listed on a name generator questionnaire eliciting people with whom respondents discussed personal issues. Network composition variables were the proportion of Latinos, Spanish-speakers, females, family, and friends listed in the name generator. Additional network composition variables included marital status and the number of adults or children in the household. Network members were predominately Latinos (95%), Spanish-speakers (80%), females (64%), and family (55%). In multivariate logistic regression analyses, gender moderated the relationship between network composition, but not size, and a health behavior. Married women were more likely to have had a routine medical check-up than married men. For both men and women, having a larger network was associated with meeting the recommendation for leisure-time physical activity. Few social network characteristics were significantly associated with health promoting behaviors, suggesting a need to examine other aspects of social relationships that may influence health behaviors. PsycINFO Database Record (c) 2014 APA, all rights reserved.

Effects of the bipartite structure of a network on performance of recommenders

Science.gov (United States)

Wang, Qing-Xian; Li, Jian; Luo, Xin; Xu, Jian-Jun; Shang, Ming-Sheng

2018-02-01

Recommender systems aim to predict people's preferences for online items by analyzing their historical behaviors. A recommender can be modeled as a high-dimensional and sparse bipartite network, where the key issue is to understand the relation between the network structure and a recommender's performance. To address this issue, we choose three network characteristics, clustering coefficient, network density and user-item ratio, as the analyzing targets. For the cluster coefficient, we adopt the Degree-preserving rewiring algorithm to obtain a series of bipartite network with varying cluster coefficient, while the degree of user and item keep unchanged. Furthermore, five state-of-the-art recommenders are applied on two real datasets. The performances of recommenders are measured by both numerical and physical metrics. These results show that a recommender's performance is positively related to the clustering coefficient of a bipartite network. Meanwhile, higher density of a bipartite network can provide more accurate but less diverse or novel recommendations. Furthermore, the user-item ratio is positively correlated with the accuracy metrics but negatively correlated with the diverse and novel metrics.

A Fluid Model for Performance Analysis in Cellular Networks

Directory of Open Access Journals (Sweden)

Coupechoux Marceau

2010-01-01

Full Text Available We propose a new framework to study the performance of cellular networks using a fluid model and we derive from this model analytical formulas for interference, outage probability, and spatial outage probability. The key idea of the fluid model is to consider the discrete base station (BS entities as a continuum of transmitters that are spatially distributed in the network. This model allows us to obtain simple analytical expressions to reveal main characteristics of the network. In this paper, we focus on the downlink other-cell interference factor (OCIF, which is defined for a given user as the ratio of its outer cell received power to its inner cell received power. A closed-form formula of the OCIF is provided in this paper. From this formula, we are able to obtain the global outage probability as well as the spatial outage probability, which depends on the location of a mobile station (MS initiating a new call. Our analytical results are compared to Monte Carlo simulations performed in a traditional hexagonal network. Furthermore, we demonstrate an application of the outage probability related to cell breathing and densification of cellular networks.

Inferring general relations between network characteristics from specific network ensembles.

Science.gov (United States)

Cardanobile, Stefano; Pernice, Volker; Deger, Moritz; Rotter, Stefan

2012-01-01

Different network models have been suggested for the topology underlying complex interactions in natural systems. These models are aimed at replicating specific statistical features encountered in real-world networks. However, it is rarely considered to which degree the results obtained for one particular network class can be extrapolated to real-world networks. We address this issue by comparing different classical and more recently developed network models with respect to their ability to generate networks with large structural variability. In particular, we consider the statistical constraints which the respective construction scheme imposes on the generated networks. After having identified the most variable networks, we address the issue of which constraints are common to all network classes and are thus suitable candidates for being generic statistical laws of complex networks. In fact, we find that generic, not model-related dependencies between different network characteristics do exist. This makes it possible to infer global features from local ones using regression models trained on networks with high generalization power. Our results confirm and extend previous findings regarding the synchronization properties of neural networks. Our method seems especially relevant for large networks, which are difficult to map completely, like the neural networks in the brain. The structure of such large networks cannot be fully sampled with the present technology. Our approach provides a method to estimate global properties of under-sampled networks in good approximation. Finally, we demonstrate on three different data sets (C. elegans neuronal network, R. prowazekii metabolic network, and a network of synonyms extracted from Roget's Thesaurus) that real-world networks have statistical relations compatible with those obtained using regression models.

Performance of social network sensors during Hurricane Sandy.

Directory of Open Access Journals (Sweden)

Yury Kryvasheyeu

Full Text Available Information flow during catastrophic events is a critical aspect of disaster management. Modern communication platforms, in particular online social networks, provide an opportunity to study such flow and derive early-warning sensors, thus improving emergency preparedness and response. Performance of the social networks sensor method, based on topological and behavioral properties derived from the "friendship paradox", is studied here for over 50 million Twitter messages posted before, during, and after Hurricane Sandy. We find that differences in users' network centrality effectively translate into moderate awareness advantage (up to 26 hours; and that geo-location of users within or outside of the hurricane-affected area plays a significant role in determining the scale of such an advantage. Emotional response appears to be universal regardless of the position in the network topology, and displays characteristic, easily detectable patterns, opening a possibility to implement a simple "sentiment sensing" technique that can detect and locate disasters.

Performance of Social Network Sensors during Hurricane Sandy

Science.gov (United States)

Kryvasheyeu, Yury; Chen, Haohui; Moro, Esteban; Van Hentenryck, Pascal; Cebrian, Manuel

2015-01-01

Information flow during catastrophic events is a critical aspect of disaster management. Modern communication platforms, in particular online social networks, provide an opportunity to study such flow and derive early-warning sensors, thus improving emergency preparedness and response. Performance of the social networks sensor method, based on topological and behavioral properties derived from the “friendship paradox”, is studied here for over 50 million Twitter messages posted before, during, and after Hurricane Sandy. We find that differences in users’ network centrality effectively translate into moderate awareness advantage (up to 26 hours); and that geo-location of users within or outside of the hurricane-affected area plays a significant role in determining the scale of such an advantage. Emotional response appears to be universal regardless of the position in the network topology, and displays characteristic, easily detectable patterns, opening a possibility to implement a simple “sentiment sensing” technique that can detect and locate disasters. PMID:25692690

A review of hospital characteristics associated with improved performance.

Science.gov (United States)

Brand, Caroline A; Barker, Anna L; Morello, Renata T; Vitale, Michael R; Evans, Sue M; Scott, Ian A; Stoelwinder, Johannes U; Cameron, Peter A

2012-10-01

The objective of this review was to critically appraise the literature relating to associations between high-level structural and operational hospital characteristics and improved performance. The Cochrane Library, MEDLINE (Ovid), CINAHL, proQuest and PsychINFO were searched for articles published between January 1996 and May 2010. Reference lists of included articles were reviewed and key journals were hand searched for relevant articles. and data extraction Studies were included if they were systematic reviews or meta-analyses, randomized controlled trials, controlled before and after studies or observational studies (cohort and cross-sectional) that were multicentre, comparative performance studies. Two reviewers independently extracted data, assigned grades of evidence according to the Australian National Health and Medical Research Council guidelines and critically appraised the included articles. Data synthesis Fifty-seven studies were reported within 12 systematic reviews and 47 observational articles. There was heterogeneity in use and definition of performance outcomes. Hospital characteristics investigated were environment (incentives, market characteristics), structure (network membership, ownership, teaching status, geographical setting, service size) and operational design (innovativeness, leadership, organizational culture, public reporting and patient safety practices, information technology systems and decision support, service activity and planning, workforce design, staff training and education). The strongest evidence for an association with overall performance was identified for computerized physician order entry systems. Some evidence supported the associations with workforce design, use of financial incentives, nursing leadership and hospital volume. There is limited, mainly low-quality evidence, supporting the associations between hospital characteristics and healthcare performance. Further characteristic-specific systematic reviews are

Structural integration and performance of inter-sectoral public health-related policy networks: An analysis across policy phases

NARCIS (Netherlands)

Peters, D. T. J. M.; Raab, J.; Grêaux, K. M.; Stronks, K.; Harting, J.

2017-01-01

Background: Inter-sectoral policy networks may be effective in addressing environmental determinants of health with interventions. However, contradictory results are reported on relations between structural network characteristics (i.e., composition and integration) and network performance, such as

Structural integration and performance of inter-sectoral public health-related policy networks : An analysis across policy phases

NARCIS (Netherlands)

Peters, Dorothee; Raab, J.; Grêaux, Kimberley M.; Stronks, Karien; Harting, Janneke

2017-01-01

Background: Inter-sectoral policy networks may be effective in addressing environmental determinants of health with interventions. However, contradictory results are reported on relations between structure and network characteristics (i.e., composition and integration) and network performance, such

performance performance analysis of gsm networks in minna

African Journals Online (AJOL)

eobe

in terms of key performance indicators (KPI) based on statistics performance indicators ... in this study. Keywords: GSM Network, Drive Test, KPI and Radio Frequency Network Optimization. 1. .... message (SMS) traffic or in scenarios where so.

THE USE OF NEURAL NETWORK TECHNOLOGY TO MODEL SWIMMING PERFORMANCE

Directory of Open Access Journals (Sweden)

António José Silva

2007-03-01

Full Text Available The aims of the present study were: to identify the factors which are able to explain the performance in the 200 meters individual medley and 400 meters front crawl events in young swimmers, to model the performance in those events using non-linear mathematic methods through artificial neural networks (multi-layer perceptrons and to assess the neural network models precision to predict the performance. A sample of 138 young swimmers (65 males and 73 females of national level was submitted to a test battery comprising four different domains: kinanthropometric evaluation, dry land functional evaluation (strength and flexibility, swimming functional evaluation (hydrodynamics, hydrostatic and bioenergetics characteristics and swimming technique evaluation. To establish a profile of the young swimmer non-linear combinations between preponderant variables for each gender and swim performance in the 200 meters medley and 400 meters font crawl events were developed. For this purpose a feed forward neural network was used (Multilayer Perceptron with three neurons in a single hidden layer. The prognosis precision of the model (error lower than 0.8% between true and estimated performances is supported by recent evidence. Therefore, we consider that the neural network tool can be a good approach in the resolution of complex problems such as performance modeling and the talent identification in swimming and, possibly, in a wide variety of sports

How Friendship Network Characteristics Influence Subjective Well-Being

NARCIS (Netherlands)

van der Horst, Mariska; Coffé, Hilde

2012-01-01

This article explores how friendship network characteristics influence subjective well-being (SWB). Using data from the 2003 General Social Survey of Canada, three components of the friendship network are differentiated: number of friends, frequency of contact, and heterogeneity of friends. We argue

Estimation of Anonymous Email Network Characteristics through Statistical Disclosure Attacks

Directory of Open Access Journals (Sweden)

Javier Portela

2016-11-01

Full Text Available Social network analysis aims to obtain relational data from social systems to identify leaders, roles, and communities in order to model profiles or predict a specific behavior in users’ network. Preserving anonymity in social networks is a subject of major concern. Anonymity can be compromised by disclosing senders’ or receivers’ identity, message content, or sender-receiver relationships. Under strongly incomplete information, a statistical disclosure attack is used to estimate the network and node characteristics such as centrality and clustering measures, degree distribution, and small-world-ness. A database of email networks in 29 university faculties is used to study the method. A research on the small-world-ness and Power law characteristics of these email networks is also developed, helping to understand the behavior of small email networks.

Estimation of Anonymous Email Network Characteristics through Statistical Disclosure Attacks

Science.gov (United States)

Portela, Javier; García Villalba, Luis Javier; Silva Trujillo, Alejandra Guadalupe; Sandoval Orozco, Ana Lucila; Kim, Tai-Hoon

2016-01-01

Social network analysis aims to obtain relational data from social systems to identify leaders, roles, and communities in order to model profiles or predict a specific behavior in users’ network. Preserving anonymity in social networks is a subject of major concern. Anonymity can be compromised by disclosing senders’ or receivers’ identity, message content, or sender-receiver relationships. Under strongly incomplete information, a statistical disclosure attack is used to estimate the network and node characteristics such as centrality and clustering measures, degree distribution, and small-world-ness. A database of email networks in 29 university faculties is used to study the method. A research on the small-world-ness and Power law characteristics of these email networks is also developed, helping to understand the behavior of small email networks. PMID:27809275

Network performance analysis

CERN Document Server

Bonald, Thomas

2013-01-01

The book presents some key mathematical tools for the performance analysis of communication networks and computer systems.Communication networks and computer systems have become extremely complex. The statistical resource sharing induced by the random behavior of users and the underlying protocols and algorithms may affect Quality of Service.This book introduces the main results of queuing theory that are useful for analyzing the performance of these systems. These mathematical tools are key to the development of robust dimensioning rules and engineering methods. A number of examples i

Assessing the efficiency of different CSO positions based on network graph characteristics.

Science.gov (United States)

Sitzenfrei, R; Urich, C; Möderl, M; Rauch, W

2013-01-01

The technical design of urban drainage systems comprises two major aspects: first, the spatial layout of the sewer system and second, the pipe-sizing process. Usually, engineers determine the spatial layout of the sewer network manually, taking into account physical features and future planning scenarios. Before the pipe-sizing process starts, it is important to determine locations of possible weirs and combined sewer overflows (CSOs) based on, e.g. distance to receiving water bodies or to a wastewater treatment plant and available space for storage units. However, positions of CSOs are also determined by topological characteristics of the sewer networks. In order to better understand the impact of placement choices for CSOs and storage units in new systems, this work aims to determine case unspecific, general rules. Therefore, based on numerous, stochastically generated virtual alpine sewer systems of different sizes it is investigated how choices for placement of CSOs and storage units have an impact on the pipe-sizing process (hence, also on investment costs) and on technical performance (CSO efficiency and flooding). To describe the impact of the topological positions of these elements in the sewer networks, graph characteristics are used. With an evaluation of 2,000 different alpine combined sewer systems, it was found that, as expected, with CSOs at more downstream positions in the network, greater construction costs and better performance regarding CSO efficiency result. At a specific point (i.e. topological network position), no significant difference (further increase) in construction costs can be identified. Contrarily, the flooding efficiency increases with more upstream positions of the CSOs. Therefore, CSO and flooding efficiency are in a trade-off conflict and a compromise is required.

Integration and the performance of healthcare networks: do integration strategies enhance efficiency, profitability, and image?

Directory of Open Access Journals (Sweden)

Thomas T.H. Wan

2001-06-01

Full Text Available Purpose: This study examines the integration effects on efficiency and financial viability of the top 100 integrated healthcare networks (IHNs in the United States. Theory: A contingency- strategic theory is used to identify the relationship of IHNs' performance to their structural and operational characteristics and integration strategies. Methods: The lists of the top 100 IHNs ranked in two years, 1998 and 1999, by the SMG Marketing Group were merged to create a database for the study. Multiple indicators were used to examine the relationship between IHNs' characteristics and their performance in efficiency and financial viability. A path analytical model was developed and validated by the Mplus statistical program. Factors influencing the top 100 IHNs' images, represented by attaining ranking among the top 100 in two consecutive years, were analysed. Results and conclusion: No positive associations were found between integration and network performance in efficiency or profits. Longitudinal data are needed to investigate the effect of integration on healthcare networks' financial performance.

An investigation and comparison on network performance analysis

OpenAIRE

Lanxiaopu, Mi

2012-01-01

This thesis is generally about network performance analysis. It contains two parts. The theory part summarizes what network performance is and inducts the methods of doing network performance analysis. To answer what network performance is, a study into what network services are is done. And based on the background research, there are two important network performance metrics: Network delay and Throughput should be included in network performance analysis. Among the methods of network a...

On the Geometrical Characteristics of Three-Dimensional Wireless Ad Hoc Networks and Their Applications

Directory of Open Access Journals (Sweden)

2006-01-01

Full Text Available In a wireless ad hoc network, messages are transmitted, received, and forwarded in a finite geometrical region and the transmission of messages is highly dependent on the locations of the nodes. Therefore the study of geometrical relationship between nodes in wireless ad hoc networks is of fundamental importance in the network architecture design and performance evaluation. However, most previous works concentrated on the networks deployed in the two-dimensional region or in the infinite three-dimensional space, while in many cases wireless ad hoc networks are deployed in the finite three-dimensional space. In this paper, we analyze the geometrical characteristics of the three-dimensional wireless ad hoc network in a finite space in the framework of random graph and deduce an expression to calculate the distance probability distribution between network nodes that are independently and uniformly distributed in a finite cuboid space. Based on the theoretical result, we present some meaningful results on the finite three-dimensional network performance, including the node degree and the max-flow capacity. Furthermore, we investigate some approximation properties of the distance probability distribution function derived in the paper.

Social Networks and Sales Performance

Directory of Open Access Journals (Sweden)

Danny Pimentel Claro

2011-05-01

Full Text Available This paper argues that an informal network can itself be a basis for the increase in a sales manager’s performance. Informal networks create a structure that surpasses the formal hierarchical structure defined by the firm. We concentrated on the advice network and considered two different views of network structure that claim to have impact on performance. To explore this claim, we examined whether sales managers develop either a highly cohesive network structure (i.e. Coleman’s view or one containing structural holes (i.e. Burt’s view in order to achieve higher sales. We also investigated the matter of tie strength put forward by Granovetter in his seminal 1973 work. Census data was collected from about 500 personnel from an agricultural input retailer having 23 divisions. Estimates from a sample of 101 sales managers showed the importance of a highly cohesive structure (degree centrality for the three measures of sales manager’s performance. The strong ties have a positive impact on performance, suggesting the importance of building up strong bonds with network contacts. Sales managers’ age, time within the retailer and education also influence performance. These results imply that firms should stimulate contacts among personnel to spread technical and commercial information.

Network Performance Improvement under Epidemic Failures in Optical Transport Networks

DEFF Research Database (Denmark)

Fagertun, Anna Manolova; Ruepp, Sarah Renée

2013-01-01

In this paper we investigate epidemic failure spreading in large- scale GMPLS-controlled transport networks. By evaluating the effect of the epidemic failure spreading on the network, we design several strategies for cost-effective network performance improvement via differentiated repair times....... First we identify the most vulnerable and the most strategic nodes in the network. Then, via extensive simulations we show that strategic placement of resources for improved failure recovery has better performance than randomly assigning lower repair times among the network nodes. Our OPNET simulation...... model can be used during the network planning process for facilitating cost- effective network survivability design....

RF Characteristics of Mica-Z Wireless Sensor Network Motes

National Research Council Canada - National Science Library

Koh, Swee J

2006-01-01

... network characteristics. Link-break and re-association distances with their corresponding RF power measurements were recorded to determine the Mica-Z s range characteristics under these different operating environments...

Analysis of Network Parameters Influencing Performance of Hybrid Multimedia Networks

Directory of Open Access Journals (Sweden)

Dominik Kovac

2013-10-01

Full Text Available Multimedia networks is an emerging subject that currently attracts the attention of research and industrial communities. This environment provides new entertainment services and business opportunities merged with all well-known network services like VoIP calls or file transfers. Such a heterogeneous system has to be able satisfy all network and end-user requirements which are increasing constantly. Therefore the simulation tools enabling deep analysis in order to find the key performance indicators and factors which influence the overall quality for specific network service the most are highly needed. This paper provides a study on the network parameters like communication technology, routing protocol, QoS mechanism, etc. and their effect on the performance of hybrid multimedia network. The analysis was performed in OPNET Modeler environment and the most interesting results are discussed at the end of this paper

Evaluate Data Center Network Performance

DEFF Research Database (Denmark)

Pilimon, Artur

through a data center network, which is usually built with layer 2 switches and layer 3 routers. The topology of the data center network is crucial for latency in the data communication to and from the data center and between servers in the data center. Tests can be conducted to measure latency and other...... Engineering, scientists evaluate data center network topologies with an SDN-based (Software-Defined Networking) control framework measuring network performance – primarily latency. This can be used to plan data center scaling by testing how a new topology will function before changes are made. Data center...... performance parameters for different data center network topologies. It is however important that tests can be repeated and reproduced to have comparable information from the tests. There are, of course, many topologies that can be used for data center networks. At DTU Fotonik, Department of Photonics...

Structural integration and performance of inter-sectoral public health-related policy networks: An analysis across policy phases.

Science.gov (United States)

Peters, D T J M; Raab, J; Grêaux, K M; Stronks, K; Harting, J

2017-12-01

Inter-sectoral policy networks may be effective in addressing environmental determinants of health with interventions. However, contradictory results are reported on relations between structural network characteristics (i.e., composition and integration) and network performance, such as addressing environmental determinants of health. This study examines these relations in different phases of the policy process. A multiple-case study was performed on four public health-related policy networks. Using a snowball method among network actors, overall and sub-networks per policy phase were identified and the policy sector of each actor was assigned. To operationalise the outcome variable, interventions were classified by the proportion of environmental determinants they addressed. In the overall networks, no relation was found between structural network characteristics and network performance. In most effective cases, the policy development sub-networks were characterised by integration with less interrelations between actors (low cohesion), more equally distributed distances between the actors (low closeness centralisation), and horizontal integration in inter-sectoral cliques. The most effective case had non-public health central actors with less connections in all sub-networks. The results suggest that, to address environmental determinants of health, sub-networks should be inter-sectorally composed in the policy development rather than in the intervention development and implementation phases, and that policy development actors should have the opportunity to connect with other actors, without strong direction from a central actor. Copyright © 2017 Elsevier B.V. All rights reserved.

Propagation Characteristics of International Space Station Wireless Local Area Network

Science.gov (United States)

Sham, Catherine C.; Hwn, Shian U.; Loh, Yin-Chung

2005-01-01

This paper describes the application of the Uniform Geometrical Theory of Diffraction (UTD) for Space Station Wireless Local Area Networks (WLANs) indoor propagation characteristics analysis. The verification results indicate good correlation between UTD computed and measured signal strength. It is observed that the propagation characteristics are quite different in the Space Station modules as compared with those in the typical indoor WLANs environment, such as an office building. The existing indoor propagation models are not readily applicable to the Space Station module environment. The Space Station modules can be regarded as oversized imperfect waveguides. Two distinct propagation regions separated by a breakpoint exist. The propagation exhibits the guided wave characteristics. The propagation loss in the Space Station, thus, is much smaller than that in the typical office building. The path loss model developed in this paper is applicable for Space Station WLAN RF coverage and link performance analysis.

Effect of mean network coordination number on dispersivity characteristics

NARCIS (Netherlands)

Vasilyev, L.; Raoof, A.; Nordbotten, J.M.

2012-01-01

In this study, we investigate the role of topology on the macroscopic (centimeter scale) dispersion characteristics derived from pore-network models.We consider 3D random porous networks extracted from a regular cubic lattice with coordination number distributed in accordance with real porous

WiMAX network performance monitoring & optimization

DEFF Research Database (Denmark)

Zhang, Qi; Dam, H

2008-01-01

frequency reuse, capacity planning, proper network dimensioning, multi-class data services and so on. Furthermore, as a small operator we also want to reduce the demand for sophisticated technicians and man labour hours. To meet these critical demands, we design a generic integrated network performance......In this paper we present our WiMAX (worldwide interoperability for microwave access) network performance monitoring and optimization solution. As a new and small WiMAX network operator, there are many demanding issues that we have to deal with, such as limited available frequency resource, tight...... this integrated network performance monitoring and optimization system in our WiMAX networks. This integrated monitoring and optimization system has such good flexibility and scalability that individual function component can be used by other operators with special needs and more advanced function components can...

Real-Time Communications in Autonomic Networks: System Implementation and Performance Evaluation

Directory of Open Access Journals (Sweden)

C. Tselios

2012-01-01

Full Text Available This paper describes the design and prototype implementation of a communication platform aiming to provide voice and video communication in a distributed networking environment. Performance considerations and network characteristics have also been taken into account in order to provide the set of properties dictated by the sensitive nature and the real-time characteristics of the targeted application scenarios. The proposed system has been evaluated both by experimental means as well as subjective tests taken by an extensive number of users. The results show that the proposed platform operates seamlessly in two hops, while in the four hops scenario, audio and video are delivered with marginal distortion. The conducted survey indicates that the user experience in terms of Quality of Service has obtained higher scores in the scenario with the two hops.

Research on Harmonic Characteristics Influence for Distribution Network with Renewable Energy

Directory of Open Access Journals (Sweden)

Huang Wei

2016-01-01

Full Text Available In order to study the influence on harmonic characteristics of distribution network with renewable energy, a simplified model of distribution network is established to analyse theory while considering the influence of cable on the system capacitive current. Establishing an actual distribution network model by Digsilent to research the harmonic characteristics impact when photovoltaic power with PV incorporated the distribution network in a variety of different access , while using constant current source model as harmonic source model which often been used in engineering practices. The simulation results show that: optimizing the access location and dispersion of PV can decrease the waveform distortion levels in distribution network and a certain number of high-order harmonic will magnify by a specific grid structure, deteriorating the distribution network power quality.

A Bayesian Network to Predict Barrier Island Geomorphologic Characteristics

Science.gov (United States)

Gutierrez, B.; Plant, N. G.; Thieler, E. R.; Turecek, A.; Stippa, S.

2014-12-01

Understanding how barrier islands along the Atlantic and Gulf coasts of the United States respond to storms and sea-level rise is an important management concern. Although these threats are well recognized, quantifying the integrated vulnerability is challenging due to the range of time and space scalesover which these processes act. Developing datasets and methods to identify the physical vulnerabilities of coastal environments due to storms and sea-level rise thus is an important scientific focus that supports land management decision making. Here we employ a Bayesian Network (BN) to model the interactions between geomorphic variables sampled from existing datasets that capture both storm-and sea-level rise related coastal evolution. The BN provides a means of estimating probabilities of changes in specific geomorphic characteristics such as foredune crest height, beach width, beach height, given knowledge of barrier island width, maximum barrier island elevation, distance from an inlet, the presence of anthropogenic modifications, and long-term shoreline change rates, which we assume to be directly related to sea-level rise. We evaluate BN skill and explore how different constraints, such as shoreline change characteristics (eroding, stable, accreting), distance to nearby inlets and island width, affect the probability distributions of future morphological characteristics. Our work demonstrates that a skillful BN can be constructed and that factors such as distance to inlet, shoreline change rate, and the presence of human alterations have the strongest influences on network performance. For Assateague Island, Maryland/Virginia, USA, we find that different shoreline change behaviors affect the probabilities of specific geomorphic characteristics, such as dune height, which allows us to identify vulnerable locations on the barrier island where habitat or infrastructure may be vulnerable to storms and sea-level rise.

Modeling Nanoscale FinFET Performance by a Neural Network Method

Directory of Open Access Journals (Sweden)

Jin He

2017-07-01

Full Text Available This paper presents a neural network method to model nanometer FinFET performance. The principle of this method is firstly introduced and its application in modeling DC and conductance characteristics of nanoscale FinFET transistor is demonstrated in detail. It is shown that this method does not need parameter extraction routine while its prediction of the transistor performance has a small relative error within 1 % compared with measured data, thus this new method is as accurate as the physics based surface potential model.

CPN based fault-tolerance performance evaluation of fieldbus for KNGR NPCS network

International Nuclear Information System (INIS)

Jung, Hyun Gi; Seong, Poong Hyun

1998-01-01

In contrast with conventional Fieldbus researches which are focused on real time performanc ignoring fault-tolerant mechanisms, the aim of this work is real-time performance evaluation of the system including fault. Because the communication network will be applied to Next Generation NPP, maintaining performance in presence of recoverable fault is important. To guarantee this in NPP Control Network, we should investigate the time characteristics of the target system in case of recoverable fault. If the time characteristics meet the requirements of the system, the faults will be recovered by Fieldbus recovery mechanisms and the system will be safe. But, if time characteristics can not meet the requirements, the faults in the Fieldbus can propagate to system failure. For this purpose, we classified the recoverable faults, made the formula which represents delays including recovery mechaisms and made simulation model. We appied the simulation model to KNGR NPCS with some assumptions. The outcome of the simulation is reallistic delays of the fault cases which have been classified. From the outcome of the simulation and the system requirements, we can calculate failure propagation probability from Fieldbus to outer system

Statistical characteristics of serious network failures in Japan

International Nuclear Information System (INIS)

Uchida, Masato

2014-01-01

Due to significant environmental changes in the telecommunications market, network failures affect socioeconomic activities more than ever before. However, the health of public networks at a national level has not been investigated in detail. In this paper, we investigate the statistical characteristics of interval, duration, and the number of users affected for serious network failures, which are defined as network failures that last for more than two hours and affect more than 30,000 users, that occurred in Japan during Japanese fiscal years 2008–2012 (April 2008–March 2013). The results show that (i) the interval follows a Poisson process, (ii) the duration follows a Pareto distribution, (iii) the number of users affected follows a piecewise Pareto distribution, (iv) the product of duration and the number of users affected roughly follow a distribution that can be derived from a convolution of two distributions of duration and the number of users affected, and (v) the relationship between duration and the number of users affected differs from service to service. - Highlights: • The statistical characteristics of serious network failures in Japan are analyzed. • The analysis is based on public information that is available at the moment. • The interval follows a Poisson process. • The duration follows a Pareto distribution. • The number of users affected follows a piecewise Pareto distribution

Personal networks in Saudi Arabia : The role of ascribed and achieved characteristics

NARCIS (Netherlands)

van Tubergen, Frank|info:eu-repo/dai/nl/271429534; Ali Al-Modaf, Obaid; Almosaed, Nora F.; Said Al-Ghamdi, Mohammed Ben

2016-01-01

This study examines how ascribed characteristics (gender and nationality) and achieved characteristics (SES) are related to the extensity and occupational resources of personal networks in Saudi Arabia. Using large-scale survey data from Jeddah, results show that networks of women are smaller and

Artificial Astrocytes Improve Neural Network Performance

Science.gov (United States)

Porto-Pazos, Ana B.; Veiguela, Noha; Mesejo, Pablo; Navarrete, Marta; Alvarellos, Alberto; Ibáñez, Oscar; Pazos, Alejandro; Araque, Alfonso

2011-01-01

Compelling evidence indicates the existence of bidirectional communication between astrocytes and neurons. Astrocytes, a type of glial cells classically considered to be passive supportive cells, have been recently demonstrated to be actively involved in the processing and regulation of synaptic information, suggesting that brain function arises from the activity of neuron-glia networks. However, the actual impact of astrocytes in neural network function is largely unknown and its application in artificial intelligence remains untested. We have investigated the consequences of including artificial astrocytes, which present the biologically defined properties involved in astrocyte-neuron communication, on artificial neural network performance. Using connectionist systems and evolutionary algorithms, we have compared the performance of artificial neural networks (NN) and artificial neuron-glia networks (NGN) to solve classification problems. We show that the degree of success of NGN is superior to NN. Analysis of performances of NN with different number of neurons or different architectures indicate that the effects of NGN cannot be accounted for an increased number of network elements, but rather they are specifically due to astrocytes. Furthermore, the relative efficacy of NGN vs. NN increases as the complexity of the network increases. These results indicate that artificial astrocytes improve neural network performance, and established the concept of Artificial Neuron-Glia Networks, which represents a novel concept in Artificial Intelligence with implications in computational science as well as in the understanding of brain function. PMID:21526157

Artificial astrocytes improve neural network performance.

Directory of Open Access Journals (Sweden)

Ana B Porto-Pazos

Full Text Available Compelling evidence indicates the existence of bidirectional communication between astrocytes and neurons. Astrocytes, a type of glial cells classically considered to be passive supportive cells, have been recently demonstrated to be actively involved in the processing and regulation of synaptic information, suggesting that brain function arises from the activity of neuron-glia networks. However, the actual impact of astrocytes in neural network function is largely unknown and its application in artificial intelligence remains untested. We have investigated the consequences of including artificial astrocytes, which present the biologically defined properties involved in astrocyte-neuron communication, on artificial neural network performance. Using connectionist systems and evolutionary algorithms, we have compared the performance of artificial neural networks (NN and artificial neuron-glia networks (NGN to solve classification problems. We show that the degree of success of NGN is superior to NN. Analysis of performances of NN with different number of neurons or different architectures indicate that the effects of NGN cannot be accounted for an increased number of network elements, but rather they are specifically due to astrocytes. Furthermore, the relative efficacy of NGN vs. NN increases as the complexity of the network increases. These results indicate that artificial astrocytes improve neural network performance, and established the concept of Artificial Neuron-Glia Networks, which represents a novel concept in Artificial Intelligence with implications in computational science as well as in the understanding of brain function.

Artificial astrocytes improve neural network performance.

Science.gov (United States)

Porto-Pazos, Ana B; Veiguela, Noha; Mesejo, Pablo; Navarrete, Marta; Alvarellos, Alberto; Ibáñez, Oscar; Pazos, Alejandro; Araque, Alfonso

2011-04-19

Compelling evidence indicates the existence of bidirectional communication between astrocytes and neurons. Astrocytes, a type of glial cells classically considered to be passive supportive cells, have been recently demonstrated to be actively involved in the processing and regulation of synaptic information, suggesting that brain function arises from the activity of neuron-glia networks. However, the actual impact of astrocytes in neural network function is largely unknown and its application in artificial intelligence remains untested. We have investigated the consequences of including artificial astrocytes, which present the biologically defined properties involved in astrocyte-neuron communication, on artificial neural network performance. Using connectionist systems and evolutionary algorithms, we have compared the performance of artificial neural networks (NN) and artificial neuron-glia networks (NGN) to solve classification problems. We show that the degree of success of NGN is superior to NN. Analysis of performances of NN with different number of neurons or different architectures indicate that the effects of NGN cannot be accounted for an increased number of network elements, but rather they are specifically due to astrocytes. Furthermore, the relative efficacy of NGN vs. NN increases as the complexity of the network increases. These results indicate that artificial astrocytes improve neural network performance, and established the concept of Artificial Neuron-Glia Networks, which represents a novel concept in Artificial Intelligence with implications in computational science as well as in the understanding of brain function.

Performance modeling of network data services

Energy Technology Data Exchange (ETDEWEB)

Haynes, R.A.; Pierson, L.G.

1997-01-01

Networks at major computational organizations are becoming increasingly complex. The introduction of large massively parallel computers and supercomputers with gigabyte memories are requiring greater and greater bandwidth for network data transfers to widely dispersed clients. For networks to provide adequate data transfer services to high performance computers and remote users connected to them, the networking components must be optimized from a combination of internal and external performance criteria. This paper describes research done at Sandia National Laboratories to model network data services and to visualize the flow of data from source to sink when using the data services.

Coexistence: Threat to the Performance of Heterogeneous Network

Science.gov (United States)

Sharma, Neetu; Kaur, Amanpreet

2010-11-01

Wireless technology is gaining broad acceptance as users opt for the freedom that only wireless network can provide. Well-accepted wireless communication technologies generally operate in frequency bands that are shared among several users, often using different RF schemes. This is true in particular for WiFi, Bluetooth, and more recently ZigBee. These all three operate in the unlicensed 2.4 GHz band, also known as ISM band, which has been key to the development of a competitive and innovative market for wireless embedded devices. But, as with any resource held in common, it is crucial that those technologies coexist peacefully to allow each user of the band to fulfill its communication goals. This has led to an increase in wireless devices intended for use in IEEE 802.11 wireless local area networks (WLANs) and wireless personal area networks (WPANs), both of which support operation in the crowded 2.4-GHz industrial, scientific and medical (ISM) band. Despite efforts made by standardization bodies to ensure smooth coexistence it may occur that communication technologies transmitting for instance at very different power levels interfere with each other. In particular, it has been pointed out that ZigBee could potentially experience interference from WiFi traffic given that while both protocols can transmit on the same channel, WiFi transmissions usually occur at much higher power level. In this work, we considered a heterogeneous network and analyzed the impact of coexistence between IEEE 802.15.4 and IEEE 802.11b. To evaluate the performance of this network, measurement and simulation study are conducted and developed in the QualNet Network simulator, version 5.0.Model is analyzed for different placement models or topologies such as Random. Grid & Uniform. Performance is analyzed on the basis of characteristics such as throughput, average jitter and average end to end delay. Here, the impact of varying different antenna gain & shadowing model for this

Analyzing topological characteristics of neuronal functional networks in the rat brain

International Nuclear Information System (INIS)

Lu, Hu; Yang, Shengtao; Song, Yuqing; Wei, Hui

2014-01-01

In this study, we recorded spike trains from brain cortical neurons of several behavioral rats in vivo by using multi-electrode recordings. An NFN was constructed in each trial, obtaining a total of 150 NFNs in this study. The topological characteristics of NFNs were analyzed by using the two most important characteristics of complex networks, namely, small-world structure and community structure. We found that the small-world properties exist in different NFNs constructed in this study. Modular function Q was used to determine the existence of community structure in NFNs, through which we found that community-structure characteristics, which are related to recorded spike train data sets, are more evident in the Y-maze task than in the DM-GM task. Our results can also be used to analyze further the relationship between small-world characteristics and the cognitive behavioral responses of rats. - Highlights: • We constructed the neuronal function networks based on the recorded neurons. • We analyzed the two main complex network characteristics, namely, small-world structure and community structure. • NFNs which were constructed based on the recorded neurons in this study exhibit small-world properties. • Some NFNs have community structure characteristics

Analyzing topological characteristics of neuronal functional networks in the rat brain

Energy Technology Data Exchange (ETDEWEB)

Lu, Hu [School of Computer Science and Communication Engineering, Jiangsu University, Jiangsu 212003 (China); School of Computer Science, Fudan University, Shanghai 200433 (China); Yang, Shengtao [Institutes of Brain Science, Fudan University, Shanghai 200433 (China); Song, Yuqing [School of Computer Science and Communication Engineering, Jiangsu University, Jiangsu 212003 (China); Wei, Hui [School of Computer Science, Fudan University, Shanghai 200433 (China)

2014-08-28

In this study, we recorded spike trains from brain cortical neurons of several behavioral rats in vivo by using multi-electrode recordings. An NFN was constructed in each trial, obtaining a total of 150 NFNs in this study. The topological characteristics of NFNs were analyzed by using the two most important characteristics of complex networks, namely, small-world structure and community structure. We found that the small-world properties exist in different NFNs constructed in this study. Modular function Q was used to determine the existence of community structure in NFNs, through which we found that community-structure characteristics, which are related to recorded spike train data sets, are more evident in the Y-maze task than in the DM-GM task. Our results can also be used to analyze further the relationship between small-world characteristics and the cognitive behavioral responses of rats. - Highlights: • We constructed the neuronal function networks based on the recorded neurons. • We analyzed the two main complex network characteristics, namely, small-world structure and community structure. • NFNs which were constructed based on the recorded neurons in this study exhibit small-world properties. • Some NFNs have community structure characteristics.

Dynamic characteristics of a cyclic-periodic structure with a piezoelectric network

Directory of Open Access Journals (Sweden)

Li Lin

2015-10-01

Full Text Available This paper deals with a cyclic-periodic structure with a piezoelectric network. In such a system, there is not only mechanical connection but also electrical connection between adjacent periodic sectors. The objective is to learn whether the presence of a piezoelectric network would change the dynamic characteristics of the system. The background of the research is about vibration reduction of a bladed disk in an aero-engine, and the system is simulated by a lumped parameter model. The dynamic equations of the system are derived, and then the analytical solution corresponding to the eigenvalue problem is given. The vibration responses to single traveling wave excitations (EO excitations and multiple traveling wave excitations (NEO excitations are studied. The results show that the presence of a piezoelectric network would change the natural frequencies of the system compared with those of the system with the piezoelectric shunt circuit. The forced response is sensitive to the connection type and the elements of the network. An energy analysis of the electro-mechanical coupling system has been performed to understand its dynamic behavior, and the following conclusion is obtained: a vibration reduction to excitations whose primary harmonic component is not zero can be achieved by a parallel piezoelectric network, while a reduction to other excitations should be based on a series piezoelectric network.

EFFECTS OF SOCIAL NETWORKING SITES ON THE ACADEMIC PERFORMANCE OF THE FIRST YEAR BSED STUDENTS OF NAVAL STATE UNIVERSITY

OpenAIRE

Christopher Rotilles Vicera, Ed. D*

2016-01-01

This study aimed to determine the effects of social networking sites on the academic performance of the students as related to the socio-demographic characteristics, social networking site usage and social network addiction. As to the socio-demographic characteristics, the respondents' age ranged from 15-17 years old or 70% of the total number of respondents. A big proportion of 70% were females. Most of the respondents were single with 98%. Their family income ranged from P5,000-9,999 with 4...

Evolution characteristics of the network core in the Facebook.

Directory of Open Access Journals (Sweden)

Jian-Guo Liu

Full Text Available Statistical properties of the static networks have been extensively studied. However, online social networks are evolving dynamically, understanding the evolving characteristics of the core is one of major concerns in online social networks. In this paper, we empirically investigate the evolving characteristics of the Facebook core. Firstly, we separate the Facebook-link(FL and Facebook-wall(FW datasets into 28 snapshots in terms of timestamps. By employing the k-core decomposition method to identify the core of each snapshot, we find that the core sizes of the FL and FW networks approximately contain about 672 and 373 nodes regardless of the exponential growth of the network sizes. Secondly, we analyze evolving topological properties of the core, including the k-core value, assortative coefficient, clustering coefficient and the average shortest path length. Empirical results show that nodes in the core are getting more interconnected in the evolving process. Thirdly, we investigate the life span of nodes belonging to the core. More than 50% nodes stay in the core for more than one year, and 19% nodes always stay in the core from the first snapshot. Finally, we analyze the connections between the core and the whole network, and find that nodes belonging to the core prefer to connect nodes with high k-core values, rather than the high degrees ones. This work could provide new insights into the online social network analysis.

Performance Analysis with Network-Enhanced Complexities: On Fading Measurements, Event-Triggered Mechanisms, and Cyber Attacks

Directory of Open Access Journals (Sweden)

Derui Ding

2014-01-01

Full Text Available Nowadays, the real-world systems are usually subject to various complexities such as parameter uncertainties, time-delays, and nonlinear disturbances. For networked systems, especially large-scale systems such as multiagent systems and systems over sensor networks, the complexities are inevitably enhanced in terms of their degrees or intensities because of the usage of the communication networks. Therefore, it would be interesting to (1 examine how this kind of network-enhanced complexities affects the control or filtering performance; and (2 develop some suitable approaches for controller/filter design problems. In this paper, we aim to survey some recent advances on the performance analysis and synthesis with three sorts of fashionable network-enhanced complexities, namely, fading measurements, event-triggered mechanisms, and attack behaviors of adversaries. First, these three kinds of complexities are introduced in detail according to their engineering backgrounds, dynamical characteristic, and modelling techniques. Then, the developments of the performance analysis and synthesis issues for various networked systems are systematically reviewed. Furthermore, some challenges are illustrated by using a thorough literature review and some possible future research directions are highlighted.

Cross Deployment Networking and Systematic Performance Analysis of Underwater Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Zhengxian Wei

2017-07-01

Full Text Available Underwater wireless sensor networks (UWSNs have become a new hot research area. However, due to the work dynamics and harsh ocean environment, how to obtain an UWSN with the best systematic performance while deploying as few sensor nodes as possible and setting up self-adaptive networking is an urgent problem that needs to be solved. Consequently, sensor deployment, networking, and performance calculation of UWSNs are challenging issues, hence the study in this paper centers on this topic and three relevant methods and models are put forward. Firstly, the normal body-centered cubic lattice to cross body-centered cubic lattice (CBCL has been improved, and a deployment process and topology generation method are built. Then most importantly, a cross deployment networking method (CDNM for UWSNs suitable for the underwater environment is proposed. Furthermore, a systematic quar-performance calculation model (SQPCM is proposed from an integrated perspective, in which the systematic performance of a UWSN includes coverage, connectivity, durability and rapid-reactivity. Besides, measurement models are established based on the relationship between systematic performance and influencing parameters. Finally, the influencing parameters are divided into three types, namely, constraint parameters, device performance and networking parameters. Based on these, a networking parameters adjustment method (NPAM for optimized systematic performance of UWSNs has been presented. The simulation results demonstrate that the approach proposed in this paper is feasible and efficient in networking and performance calculation of UWSNs.

Wireless networked music performance

CERN Document Server

Gabrielli, Leonardo

2016-01-01

This book presents a comprehensive overview of the state of the art in Networked Music Performance (NMP) and a historical survey of computer music networking. It introduces current technical trends in NMP and technical issues yet to be addressed. It also lists wireless communication protocols and compares these to the requirements of NMP. Practical use cases and advancements are also discussed.

Performance Evaluation of Moving Small-Cell Network with Proactive Cache

Directory of Open Access Journals (Sweden)

Young Min Kwon

2016-01-01

Full Text Available Due to rapid growth in mobile traffic, mobile network operators (MNOs are considering the deployment of moving small-cells (mSCs. mSC is a user-centric network which provides voice and data services during mobility. mSC can receive and forward data traffic via wireless backhaul and sidehaul links. In addition, due to the predictive nature of users demand, mSCs can proactively cache the predicted contents in off-peak-traffic periods. Due to these characteristics, MNOs consider mSCs as a cost-efficient solution to not only enhance the system capacity but also provide guaranteed quality of service (QoS requirements to moving user equipment (UE in peak-traffic periods. In this paper, we conduct extensive system level simulations to analyze the performance of mSCs with varying cache size and content popularity and their effect on wireless backhaul load. The performance evaluation confirms that the QoS of moving small-cell UE (mSUE notably improves by using mSCs together with proactive caching. We also show that the effective use of proactive cache significantly reduces the wireless backhaul load and increases the overall network capacity.

Performance Evaluation Of Mobile Cellular Networks In Nigeria

OpenAIRE

Shoewu, O.O

2018-01-01

The aim of this paper is to evaluate the performance of mobile networks such as MTN, GLO, and ETISALAT in Nigeria and suggest ways the performance of digital cellular networks can improve to minimize some of its present short comings or limitations. This paper discusses the performance improvement of digital cellular networks. A non- CDMA cellular network is use in an overall wireless environment for the purpose of this paper. This paper also discusses the performance assessment of three mobi...

On the network protocol performance evaluation for large scale communication system of nuclear plant

International Nuclear Information System (INIS)

Song, K. S.; Lee, T. H.; Kim, H. R.; Kim, D. H.; Ku, I. S.

1998-01-01

Computer technology has been dramatically advanced and it is now natural to apply digital network technology into nuclear plants. Communication architecture for nuclear plant defines the coordination of safety reactor control, balance of plant, subsystem utilities, and plant monitoring functions, and how they are connected and their user interface to guarantee plant performance and guarantee safety requirements. Therefore, to implement a digital network for control and monitoring systems of advanced nuclear plant needs systematic design and evaluation procedures because of responsive and hard real-time process characteristics of nuclear plant. In this paper, we evaluate several digital network protocols in terms of network delay, link failure effects to hard real-time requirements with full scale traffic

Comparative indicators for cancer network management in England: Availability, characteristics and presentation

Directory of Open Access Journals (Sweden)

Coleman Michel P

2008-02-01

Full Text Available Abstract Background In 2000, the national cancer plan for England created 34 cancer networks, new organisational structures to coordinate services across populations varying between a half and three million people. We investigated the availability of data sets reflecting measures of structure, process and outcome that could be used to support network management. Methods We investigated the properties of national data sets relating to four common cancers – breast, colorectal, lung and prostate. We reviewed the availability and completeness of these data sets, identified leading items within each set and put them into tables of the 34 cancer networks. We also investigated methods of presentation. Results The Acute Hospitals Portfolio and the Cancer Standards Peer Review recorded structural characteristics at hospital and cancer service level. Process measures included Hospital Episode Statistics, recording admissions, and Hospital Waiting-List data. Patient outcome measures included the National Survey of Patient Satisfaction for cancer, and cancer survival, drawn from cancer registration. Data were drawn together to provide an exemplar indicator set a single network, and methods of graphical presentation were considered. Conclusion While not as yet used together in practice, comparative indicators are available within the National Health Service in England for use in performance assessment by cancer networks.

Network characteristics for server selection in online games

Science.gov (United States)

Claypool, Mark

2008-01-01

Online gameplay is impacted by the network characteristics of players connected to the same server. Unfortunately, the network characteristics of online game servers are not well-understood, particularly for groups that wish to play together on the same server. As a step towards a remedy, this paper presents analysis of an extensive set of measurements of game servers on the Internet. Over the course of many months, actual Internet game servers were queried simultaneously by twenty-five emulated game clients, with both servers and clients spread out on the Internet. The data provides statistics on the uptime and populations of game servers over a month long period an an in-depth look at the suitability for game servers for multi-player server selection, concentrating on characteristics critical to playability--latency and fairness. Analysis finds most game servers have latencies suitable for third-person and omnipresent games, such as real-time strategy, sports and role-playing games, providing numerous server choices for game players. However, far fewer game servers have the low latencies required for first-person games, such as shooters or race games. In all cases, groups that wish to play together have a greatly reduced set of servers from which to choose because of inherent unfairness in server latencies and server selection is particularly limited as the group size increases. These results hold across different game types and even across different generations of games. The data should be useful for game developers and network researchers that seek to improve game server selection, whether for single or multiple players.

Network performance for graphical control systems

International Nuclear Information System (INIS)

Clout, P.; Geib, M.; Westervelt, R.

1992-01-01

Vsystem is a toolbox for building graphically-based control systems. The real-tiem database component, Vaccess, includes all the networking support necessary to build multi-computer control systems. Vaccess has two modes of database access, synchronous and asynchronous. Vdraw is another component of Vsystem that allows developers and users to develop control screens and windows by drawing rather than programming. Based on X-windows, Vsystem provides the possibility of running Vdraw either on the workstation with the graphics or on the computer with the database. We have made some measurements on the cpu loading, elapsed time and the network loading to give some guidance in system configuration performance. It will be seen that asynchronous network access gives large performance increases and that the network database change notification protocol can be either more or less efficient than the X-window network protocol, depending on the graphical representation of the data. (author)

Social Network Characteristics and Daily Smoking among Young Adults in Sweden

Directory of Open Access Journals (Sweden)

Mikael Rostila

2013-11-01

Full Text Available A large number of studies have shown that friends’ smoking behavior is strongly associated with an individual’s own risk for smoking. However, few studies have examined whether other features of social networks, independently or conjointly with friends’ smoking behavior, may influence the risk for smoking. Because it is characterized by the growing importance of friendship networks, the transition from adolescence to young adulthood may constitute a particularly relevant period on which to focus our investigation of network influences on smoking behavior. The aim of this study was therefore to examine the consequences of peer smoking as well as other network characteristics (friends’ other health behaviors, relationship content, and structural aspects of the network on the risk for smoking among young adults. The data was based on a cross-sectional survey of Swedish 19-year-olds carried out in 2009 (n = 5,695 with a response rate of 51.6%. Logistic regression was the primary method of analysis. The results show that having a large percentage of smokers in one’s network was by far the most important risk factor for daily smoking. The risk of daily smoking was 21.20 (CI 14.24. 31.54 if 76%–100% of the network members smoked. Having a high percentage of physically active friends was inversely associated with daily smoking. The risk of smoking was 0.65 (CI 0.42. 1.00 if 76%–100% of the network members were physically active. No main associations between the other network characteristics (relationship content and structural aspects of the network and smoking were found. However, there was an interaction between the percentage of smokers in the network and relationship content (i.e., trust, relationship quality and propensity to discuss problems: positive relationship content in combination with peer smoking may increase the risk of smoking. Women with a high percentage of smokers in their networks were also at higher risk of daily

Dismissing Attachment Characteristics Dynamically Modulate Brain Networks Subserving Social Aversion.

Science.gov (United States)

Krause, Anna Linda; Borchardt, Viola; Li, Meng; van Tol, Marie-José; Demenescu, Liliana Ramona; Strauss, Bernhard; Kirchmann, Helmut; Buchheim, Anna; Metzger, Coraline D; Nolte, Tobias; Walter, Martin

2016-01-01

Attachment patterns influence actions, thoughts and feeling through a person's "inner working model". Speech charged with attachment-dependent content was proposed to modulate the activation of cognitive-emotional schemata in listeners. We performed a 7 Tesla rest-task-rest functional magnetic resonance imaging (fMRI)-experiment, presenting auditory narratives prototypical of dismissing attachment representations to investigate their effect on 23 healthy males. We then examined effects of participants' attachment style and childhood trauma on brain state changes using seed-based functional connectivity (FC) analyses, and finally tested whether subjective differences in responsivity to narratives could be predicted by baseline network states. In comparison to a baseline state, we observed increased FC in a previously described "social aversion network" including dorsal anterior cingulated cortex (dACC) and left anterior middle temporal gyrus (aMTG) specifically after exposure to insecure-dismissing attachment narratives. Increased dACC-seeded FC within the social aversion network was positively related to the participants' avoidant attachment style and presence of a history of childhood trauma. Anxious attachment style on the other hand was positively correlated with FC between the dACC and a region outside of the "social aversion network", namely the dorsolateral prefrontal cortex, which suggests decreased network segregation as a function of anxious attachment. Finally, the extent of subjective experience of friendliness towards the dismissing narrative was predicted by low baseline FC-values between hippocampus and inferior parietal lobule (IPL). Taken together, our study demonstrates an activation of networks related to social aversion in terms of increased connectivity after listening to insecure-dismissing attachment narratives. A causal interrelation of brain state changes and subsequent changes in social reactivity was further supported by our observation of

Social Network Analysis and Qualitative Interviews for Assessing Geographic Characteristics of Tourism Business Networks.

Science.gov (United States)

Kelman, Ilan; Luthe, Tobias; Wyss, Romano; Tørnblad, Silje H; Evers, Yvette; Curran, Marina Martin; Williams, Richard J; Berlow, Eric L

2016-01-01

This study integrates quantitative social network analysis (SNA) and qualitative interviews for understanding tourism business links in isolated communities through analysing spatial characteristics. Two case studies are used, the Surselva-Gotthard region in the Swiss Alps and Longyearbyen in the Arctic archipelago of Svalbard, to test the spatial characteristics of physical proximity, isolation, and smallness for understanding tourism business links. In the larger Surselva-Gotthard region, we found a strong relationship between geographic separation of the three communities on compartmentalization of the collaboration network. A small set of businesses played a central role in steering collaborative decisions for this community, while a group of structurally 'peripheral' actors were less influential. By contrast, the business community in Svalbard showed compartmentalization that was independent of geographic distance between actors. Within towns of similar size and governance scale, Svalbard is more compartmentalized, and those compartments are not driven by geographic separation of the collaboration clusters. This compartmentalization in Svalbard was reflected in a lower density of formal business collaboration ties compared to the communities of the Alps. We infer that the difference is due to Svalbard having higher cultural diversity and population turnover than the Alps communities. We propose that integrating quantitative network analysis from simple surveys with qualitative interviews targeted from the network results is an efficient general approach to identify regionally specific constraints and opportunities for effective governance.

Social Network Analysis and Qualitative Interviews for Assessing Geographic Characteristics of Tourism Business Networks.

Directory of Open Access Journals (Sweden)

Ilan Kelman

Full Text Available This study integrates quantitative social network analysis (SNA and qualitative interviews for understanding tourism business links in isolated communities through analysing spatial characteristics. Two case studies are used, the Surselva-Gotthard region in the Swiss Alps and Longyearbyen in the Arctic archipelago of Svalbard, to test the spatial characteristics of physical proximity, isolation, and smallness for understanding tourism business links. In the larger Surselva-Gotthard region, we found a strong relationship between geographic separation of the three communities on compartmentalization of the collaboration network. A small set of businesses played a central role in steering collaborative decisions for this community, while a group of structurally 'peripheral' actors were less influential. By contrast, the business community in Svalbard showed compartmentalization that was independent of geographic distance between actors. Within towns of similar size and governance scale, Svalbard is more compartmentalized, and those compartments are not driven by geographic separation of the collaboration clusters. This compartmentalization in Svalbard was reflected in a lower density of formal business collaboration ties compared to the communities of the Alps. We infer that the difference is due to Svalbard having higher cultural diversity and population turnover than the Alps communities. We propose that integrating quantitative network analysis from simple surveys with qualitative interviews targeted from the network results is an efficient general approach to identify regionally specific constraints and opportunities for effective governance.

Social Network Analysis and Qualitative Interviews for Assessing Geographic Characteristics of Tourism Business Networks

Science.gov (United States)

Luthe, Tobias; Wyss, Romano; Tørnblad, Silje H.; Evers, Yvette; Curran, Marina Martin; Williams, Richard J.; Berlow, Eric L.

2016-01-01

This study integrates quantitative social network analysis (SNA) and qualitative interviews for understanding tourism business links in isolated communities through analysing spatial characteristics. Two case studies are used, the Surselva-Gotthard region in the Swiss Alps and Longyearbyen in the Arctic archipelago of Svalbard, to test the spatial characteristics of physical proximity, isolation, and smallness for understanding tourism business links. In the larger Surselva-Gotthard region, we found a strong relationship between geographic separation of the three communities on compartmentalization of the collaboration network. A small set of businesses played a central role in steering collaborative decisions for this community, while a group of structurally ‘peripheral’ actors were less influential. By contrast, the business community in Svalbard showed compartmentalization that was independent of geographic distance between actors. Within towns of similar size and governance scale, Svalbard is more compartmentalized, and those compartments are not driven by geographic separation of the collaboration clusters. This compartmentalization in Svalbard was reflected in a lower density of formal business collaboration ties compared to the communities of the Alps. We infer that the difference is due to Svalbard having higher cultural diversity and population turnover than the Alps communities. We propose that integrating quantitative network analysis from simple surveys with qualitative interviews targeted from the network results is an efficient general approach to identify regionally specific constraints and opportunities for effective governance. PMID:27258007

Virtual Networking Performance in OpenStack Platform for Network Function Virtualization

Directory of Open Access Journals (Sweden)

Franco Callegati

2016-01-01

Full Text Available The emerging Network Function Virtualization (NFV paradigm, coupled with the highly flexible and programmatic control of network devices offered by Software Defined Networking solutions, enables unprecedented levels of network virtualization that will definitely change the shape of future network architectures, where legacy telco central offices will be replaced by cloud data centers located at the edge. On the one hand, this software-centric evolution of telecommunications will allow network operators to take advantage of the increased flexibility and reduced deployment costs typical of cloud computing. On the other hand, it will pose a number of challenges in terms of virtual network performance and customer isolation. This paper intends to provide some insights on how an open-source cloud computing platform such as OpenStack implements multitenant network virtualization and how it can be used to deploy NFV, focusing in particular on packet forwarding performance issues. To this purpose, a set of experiments is presented that refer to a number of scenarios inspired by the cloud computing and NFV paradigms, considering both single tenant and multitenant scenarios. From the results of the evaluation it is possible to highlight potentials and limitations of running NFV on OpenStack.

Topology influences performance in the associative memory neural networks

International Nuclear Information System (INIS)

Lu Jianquan; He Juan; Cao Jinde; Gao Zhiqiang

2006-01-01

To explore how topology affects performance within Hopfield-type associative memory neural networks (AMNNs), we studied the computational performance of the neural networks with regular lattice, random, small-world, and scale-free structures. In this Letter, we found that the memory performance of neural networks obtained through asynchronous updating from 'larger' nodes to 'smaller' nodes are better than asynchronous updating in random order, especially for the scale-free topology. The computational performance of associative memory neural networks linked by the above-mentioned network topologies with the same amounts of nodes (neurons) and edges (synapses) were studied respectively. Along with topologies becoming more random and less locally disordered, we will see that the performance of associative memory neural network is quite improved. By comparing, we show that the regular lattice and random network form two extremes in terms of patterns stability and retrievability. For a network, its patterns stability and retrievability can be largely enhanced by adding a random component or some shortcuts to its structured component. According to the conclusions of this Letter, we can design the associative memory neural networks with high performance and minimal interconnect requirements

Diversity Performance Analysis on Multiple HAP Networks

Science.gov (United States)

Dong, Feihong; Li, Min; Gong, Xiangwu; Li, Hongjun; Gao, Fengyue

2015-01-01

One of the main design challenges in wireless sensor networks (WSNs) is achieving a high-data-rate transmission for individual sensor devices. The high altitude platform (HAP) is an important communication relay platform for WSNs and next-generation wireless networks. Multiple-input multiple-output (MIMO) techniques provide the diversity and multiplexing gain, which can improve the network performance effectively. In this paper, a virtual MIMO (V-MIMO) model is proposed by networking multiple HAPs with the concept of multiple assets in view (MAV). In a shadowed Rician fading channel, the diversity performance is investigated. The probability density function (PDF) and cumulative distribution function (CDF) of the received signal-to-noise ratio (SNR) are derived. In addition, the average symbol error rate (ASER) with BPSK and QPSK is given for the V-MIMO model. The system capacity is studied for both perfect channel state information (CSI) and unknown CSI individually. The ergodic capacity with various SNR and Rician factors for different network configurations is also analyzed. The simulation results validate the effectiveness of the performance analysis. It is shown that the performance of the HAPs network in WSNs can be significantly improved by utilizing the MAV to achieve overlapping coverage, with the help of the V-MIMO techniques. PMID:26134102

Diversity Performance Analysis on Multiple HAP Networks

Directory of Open Access Journals (Sweden)

Feihong Dong

2015-06-01

Full Text Available One of the main design challenges in wireless sensor networks (WSNs is achieving a high-data-rate transmission for individual sensor devices. The high altitude platform (HAP is an important communication relay platform for WSNs and next-generation wireless networks. Multiple-input multiple-output (MIMO techniques provide the diversity and multiplexing gain, which can improve the network performance effectively. In this paper, a virtual MIMO (V-MIMO model is proposed by networking multiple HAPs with the concept of multiple assets in view (MAV. In a shadowed Rician fading channel, the diversity performance is investigated. The probability density function (PDF and cumulative distribution function (CDF of the received signal-to-noise ratio (SNR are derived. In addition, the average symbol error rate (ASER with BPSK and QPSK is given for the V-MIMO model. The system capacity is studied for both perfect channel state information (CSI and unknown CSI individually. The ergodic capacity with various SNR and Rician factors for different network configurations is also analyzed. The simulation results validate the effectiveness of the performance analysis. It is shown that the performance of the HAPs network in WSNs can be significantly improved by utilizing the MAV to achieve overlapping coverage, with the help of the V-MIMO techniques.

Experimental and artificial neural network based prediction of performance and emission characteristics of DI diesel engine using Calophyllum inophyllum methyl ester at different nozzle opening pressure

Science.gov (United States)

Vairamuthu, G.; Thangagiri, B.; Sundarapandian, S.

2018-01-01

The present work investigates the effect of varying Nozzle Opening Pressures (NOP) from 220 bar to 250 bar on performance, emissions and combustion characteristics of Calophyllum inophyllum Methyl Ester (CIME) in a constant speed, Direct Injection (DI) diesel engine using Artificial Neural Network (ANN) approach. An ANN model has been developed to predict a correlation between specific fuel consumption (SFC), brake thermal efficiency (BTE), exhaust gas temperature (EGT), Unburnt hydrocarbon (UBHC), CO, CO2, NOx and smoke density using load, blend (B0 and B100) and NOP as input data. A standard Back-Propagation Algorithm (BPA) for the engine is used in this model. A Multi Layer Perceptron network (MLP) is used for nonlinear mapping between the input and the output parameters. An ANN model can predict the performance of diesel engine and the exhaust emissions with correlation coefficient (R2) in the range of 0.98-1. Mean Relative Errors (MRE) values are in the range of 0.46-5.8%, while the Mean Square Errors (MSE) are found to be very low. It is evident that the ANN models are reliable tools for the prediction of DI diesel engine performance and emissions. The test results show that the optimum NOP is 250 bar with B100.

‘Down-Stream’ Network Characteristics, Broker Functions and New Product Development Success

DEFF Research Database (Denmark)

Smed, Marie; Salomo, Søren; Li, Ying

2011-01-01

that small entrepreneurial start up company’s supply knowledge to network alliances with well-established and financially strong companies. However, in the later stages of development the main influence of external partnerships is described as financial support and joining distribution efforts, rather than...... of later stage product development tasks. While networks can be characterized by a number of measures like breadth, density, and structural characteristics, more recent developments in network and alliance management need to be specifically accounted for. In particular, it is observed that companies today...... richness to our conceptual model, we further include qualitative case studies supporting grounded theory building. In sum, this paper contributes to the literature by the following: (1) We develop a systematic overview over network characteristics shown to have impact for new product development. (2) We...

Structure and Topology Dynamics of Hyper-Frequency Networks during Rest and Auditory Oddball Performance.

Science.gov (United States)

Müller, Viktor; Perdikis, Dionysios; von Oertzen, Timo; Sleimen-Malkoun, Rita; Jirsa, Viktor; Lindenberger, Ulman

2016-01-01

Resting-state and task-related recordings are characterized by oscillatory brain activity and widely distributed networks of synchronized oscillatory circuits. Electroencephalographic recordings (EEG) were used to assess network structure and network dynamics during resting state with eyes open and closed, and auditory oddball performance through phase synchronization between EEG channels. For this assessment, we constructed a hyper-frequency network (HFN) based on within- and cross-frequency coupling (WFC and CFC, respectively) at 10 oscillation frequencies ranging between 2 and 20 Hz. We found that CFC generally differentiates between task conditions better than WFC. CFC was the highest during resting state with eyes open. Using a graph-theoretical approach (GTA), we found that HFNs possess small-world network (SWN) topology with a slight tendency to random network characteristics. Moreover, analysis of the temporal fluctuations of HFNs revealed specific network topology dynamics (NTD), i.e., temporal changes of different graph-theoretical measures such as strength, clustering coefficient, characteristic path length (CPL), local, and global efficiency determined for HFNs at different time windows. The different topology metrics showed significant differences between conditions in the mean and standard deviation of these metrics both across time and nodes. In addition, using an artificial neural network approach, we found stimulus-related dynamics that varied across the different network topology metrics. We conclude that functional connectivity dynamics (FCD), or NTD, which was found using the HFN approach during rest and stimulus processing, reflects temporal and topological changes in the functional organization and reorganization of neuronal cell assemblies.

Building and measuring a high performance network architecture

Energy Technology Data Exchange (ETDEWEB)

Kramer, William T.C.; Toole, Timothy; Fisher, Chuck; Dugan, Jon; Wheeler, David; Wing, William R; Nickless, William; Goddard, Gregory; Corbato, Steven; Love, E. Paul; Daspit, Paul; Edwards, Hal; Mercer, Linden; Koester, David; Decina, Basil; Dart, Eli; Paul Reisinger, Paul; Kurihara, Riki; Zekauskas, Matthew J; Plesset, Eric; Wulf, Julie; Luce, Douglas; Rogers, James; Duncan, Rex; Mauth, Jeffery

2001-04-20

Once a year, the SC conferences present a unique opportunity to create and build one of the most complex and highest performance networks in the world. At SC2000, large-scale and complex local and wide area networking connections were demonstrated, including large-scale distributed applications running on different architectures. This project was designed to use the unique opportunity presented at SC2000 to create a testbed network environment and then use that network to demonstrate and evaluate high performance computational and communication applications. This testbed was designed to incorporate many interoperable systems and services and was designed for measurement from the very beginning. The end results were key insights into how to use novel, high performance networking technologies and to accumulate measurements that will give insights into the networks of the future.

[Social network analysis and high risk behavior characteristics of recreational drug users: a qualitative study].

Science.gov (United States)

Wu, Di; Wang, Zhenhong; Jiang, Zhenxia; Fu, Xiaojing; Li, Hui; Zhang, Dapeng; Liu, Hui; Hu, Yifei

2014-11-01

To understand the characteristics of recreational drug users' behaviors and social network, as well as their potential impact to the transmission of sexual transmitted infections (STI). Qualitative interview was used to collect information on rough estimation of population size and behavior change before and after recreational drug use. A total of 120 participants were recruited by convenient sampling from April to October, 2013 in a community of Qingdao city. Blood specimens were taken for HIV/syphilis serological testing and social network analysis was performed to understand the characteristics of their behavior and social network. All participants used methamphetamine and 103 of them showed social connection. The prevalence of syphilis and HIV were 24.2% (29/120) and 2.5% (3/120) respectively. The estimated size of recreational drug users was big with a wide diversity of occupations and age range, and males were more frequent than females. Drug use may affect condom use and frequent drug users showed symptom of psychosis and neuro-toxicities. The size of social network was 2.45 ± 1.63 in the past 6 months, which indicated an increasing trend of the sexual partner number and risky behaviors. Recreational drug use could increase the size of social network among sex partners, the frequency of risky sexual behaviors and syphilis prevalence, which indicate a high risk of HIV/STI among this population as well as a huge burden of disease prevention and control in the future.

Performance Monitoring Techniques Supporting Cognitive Optical Networking

DEFF Research Database (Denmark)

Caballero Jambrina, Antonio; Borkowski, Robert; Zibar, Darko

2013-01-01

High degree of heterogeneity of future optical networks, such as services with different quality-of-transmission requirements, modulation formats and switching techniques, will pose a challenge for the control and optimization of different parameters. Incorporation of cognitive techniques can help...... to solve this issue by realizing a network that can observe, act, learn and optimize its performance, taking into account end-to-end goals. In this letter we present the approach of cognition applied to heterogeneous optical networks developed in the framework of the EU project CHRON: Cognitive...... Heterogeneous Reconfigurable Optical Network. We focus on the approaches developed in the project for optical performance monitoring, which enable the feedback from the physical layer to the cognitive decision system by providing accurate description of the performance of the established lightpaths....

Optical Networks Solutions planning - performances - management

DEFF Research Database (Denmark)

Fenger, Christian

2002-01-01

It has been a decisive goal in the compilation of this thesis to make us capable of realizing the future national and regional telecommunication networks in an efficient and resource optimal way. By future telecommunication network is assumed an all optical network where the information in transit...... are kept optical and not converted into the optical domain. The focus is on the scientific results achieved throughout the Ph.D. period. Five subjects – all increasing the understanding of optical networks – are studied. Static wavelength routed optical networks are studied. Management on terms...... of lightpath allocation and design is considered. By using statistical models (simultaneous analysis of many networks) the correspondence between parameters determining the network topology and the performance of the optical network is found. These dependencies are important knowledge in the process...

Optical interconnection networks for high-performance computing systems

International Nuclear Information System (INIS)

Biberman, Aleksandr; Bergman, Keren

2012-01-01

Enabled by silicon photonic technology, optical interconnection networks have the potential to be a key disruptive technology in computing and communication industries. The enduring pursuit of performance gains in computing, combined with stringent power constraints, has fostered the ever-growing computational parallelism associated with chip multiprocessors, memory systems, high-performance computing systems and data centers. Sustaining these parallelism growths introduces unique challenges for on- and off-chip communications, shifting the focus toward novel and fundamentally different communication approaches. Chip-scale photonic interconnection networks, enabled by high-performance silicon photonic devices, offer unprecedented bandwidth scalability with reduced power consumption. We demonstrate that the silicon photonic platforms have already produced all the high-performance photonic devices required to realize these types of networks. Through extensive empirical characterization in much of our work, we demonstrate such feasibility of waveguides, modulators, switches and photodetectors. We also demonstrate systems that simultaneously combine many functionalities to achieve more complex building blocks. We propose novel silicon photonic devices, subsystems, network topologies and architectures to enable unprecedented performance of these photonic interconnection networks. Furthermore, the advantages of photonic interconnection networks extend far beyond the chip, offering advanced communication environments for memory systems, high-performance computing systems, and data centers. (review article)

Experimental performance evaluation of software defined networking (SDN) based data communication networks for large scale flexi-grid optical networks.

Science.gov (United States)

Zhao, Yongli; He, Ruiying; Chen, Haoran; Zhang, Jie; Ji, Yuefeng; Zheng, Haomian; Lin, Yi; Wang, Xinbo

2014-04-21

Software defined networking (SDN) has become the focus in the current information and communication technology area because of its flexibility and programmability. It has been introduced into various network scenarios, such as datacenter networks, carrier networks, and wireless networks. Optical transport network is also regarded as an important application scenario for SDN, which is adopted as the enabling technology of data communication networks (DCN) instead of general multi-protocol label switching (GMPLS). However, the practical performance of SDN based DCN for large scale optical networks, which is very important for the technology selection in the future optical network deployment, has not been evaluated up to now. In this paper we have built a large scale flexi-grid optical network testbed with 1000 virtual optical transport nodes to evaluate the performance of SDN based DCN, including network scalability, DCN bandwidth limitation, and restoration time. A series of network performance parameters including blocking probability, bandwidth utilization, average lightpath provisioning time, and failure restoration time have been demonstrated under various network environments, such as with different traffic loads and different DCN bandwidths. The demonstration in this work can be taken as a proof for the future network deployment.

Social networks : Effects on Identification, Performance and Satisfaction Effects on identification, performance and satisfaction

NARCIS (Netherlands)

Stormbroek-Burgers, van R.G.B.M.; Montfort, van K.; Sluis, van der E.C. (Lidewey)

2011-01-01

This study contributes to research on the impact of social networks on organizational outcomes in the context of the increasing number of professionals in the Netherlands. The aim of this study was to get insight into the characteristics of professionals’ social networks and to examine the effect of

Modeling Travel Time Reliability of Road Network Considering Connected Vehicle Guidance Characteristics Indexes

Directory of Open Access Journals (Sweden)

Jiangfeng Wang

2017-01-01

Full Text Available Travel time reliability (TTR is one of the important indexes for effectively evaluating the performance of road network, and TTR can effectively be improved using the real-time traffic guidance information. Compared with traditional traffic guidance, connected vehicle (CV guidance can provide travelers with more timely and accurate travel information, which can further improve the travel efficiency of road network. Five CV characteristics indexes are selected as explanatory variables including the Congestion Level (CL, Penetration Rate (PR, Compliance Rate (CR, release Delay Time (DT, and Following Rate (FR. Based on the five explanatory variables, a TTR model is proposed using the multilogistic regression method, and the prediction accuracy and the impact of characteristics indexes on TTR are analyzed using a CV guidance scenario. The simulation results indicate that 80% of the RMSE is concentrated within the interval of 0 to 0.0412. The correlation analysis of characteristics indexes shows that the influence of CL, PR, CR, and DT on the TTR is significant. PR and CR have a positive effect on TTR, and the average improvement rate is about 77.03% and 73.20% with the increase of PR and CR, respectively, while CL and DT have a negative effect on TTR, and TTR decreases by 31.21% with the increase of DT from 0 to 180 s.

Performance testing framework for smart grid communication network

International Nuclear Information System (INIS)

Quang, D N; See, O H; Chee, L L; Xuen, C Y; Karuppiah, S

2013-01-01

Smart grid communication network is comprised of different communication mediums and technologies. Performance evaluation is one of the main concerns in smart grid communication system. In any smart grid communication implementation, to determine the performance factor of the network, a testing of an end-to-end process flow is required. Therefore, an effective and coordinated testing procedure plays a crucial role in evaluating the performance of smart grid communications. In this paper, a testing framework is proposed as a guideline to analyze and assess the performance of smart grid communication network.

Academic Performance and the Use of Social Networks

Directory of Open Access Journals (Sweden)

Jéssica Ribeiro Rangel

2016-08-01

Full Text Available This study aimed to investigate whether the use of social networks influences on the academic performance of students in the undergraduate program in accounting. Data were collected from 322 students of the course of a federal University of the State of Minas Gerais, Brazil. The regression results show that the variables "gender", "motivation" and "classification in the University entrance examination" are significant in explaining students' academic performance measured by the Grade Point Average (GPA. The results show that the performance of male students is lower than that of female students at the level of 5%. Also was identified that the greater the student's motivation level, the greater your academic performance (at the level of 1 percent. Finally, it was observed that the best ranked students in the University entrance examination, the higher their academic performance. However, none of the variables relating to the use of social networks ("familiarity with technological resources", "hours", "Internet hours on social networks" and "use of social networks to study" presented relation with academic performance. In other words, these results show that the use of social networks does not have positive or negative impacts directly on academic performance. We can conclude for the sample analyzed, that use of social networks during the academic period does not influence significantly the performance of the students. However, you can verify that the motivation is directly related to the academic performance of the Accounting student with regard to perception of motivation, to familiarity with technological resources and the use of applications.

Social Networking and Academic Performance: A Review

Science.gov (United States)

Doleck, Tenzin; Lajoie, Susanne

2018-01-01

The ubiquitous use of social networking sites by students and the potential impacts of such use on academic performance are of both theoretical and practical importance. Hence, this paper addresses the question: how does the use of social networking sites influence academic performance? The present review synthesizes the empirical findings of the…

Artificial neural network analysis based on genetic algorithm to predict the performance characteristics of a cross flow cooling tower

Science.gov (United States)

Wu, Jiasheng; Cao, Lin; Zhang, Guoqiang

2018-02-01

Cooling tower of air conditioning has been widely used as cooling equipment, and there will be broad application prospect if it can be reversibly used as heat source under heat pump heating operation condition. In view of the complex non-linear relationship of each parameter in the process of heat and mass transfer inside tower, In this paper, the BP neural network model based on genetic algorithm optimization (GABP neural network model) is established for the reverse use of cross flow cooling tower. The model adopts the structure of 6 inputs, 13 hidden nodes and 8 outputs. With this model, the outlet air dry bulb temperature, wet bulb temperature, water temperature, heat, sensible heat ratio and heat absorbing efficiency, Lewis number, a total of 8 the proportion of main performance parameters were predicted. Furthermore, the established network model is used to predict the water temperature and heat absorption of the tower at different inlet temperatures. The mean relative error MRE between BP predicted value and experimental value are 4.47%, 3.63%, 2.38%, 3.71%, 6.35%,3.14%, 13.95% and 6.80% respectively; the mean relative error MRE between GABP predicted value and experimental value are 2.66%, 3.04%, 2.27%, 3.02%, 6.89%, 3.17%, 11.50% and 6.57% respectively. The results show that the prediction results of GABP network model are better than that of BP network model; the simulation results are basically consistent with the actual situation. The GABP network model can well predict the heat and mass transfer performance of the cross flow cooling tower.

Identification and adaptive neural network control of a DC motor system with dead-zone characteristics.

Science.gov (United States)

Peng, Jinzhu; Dubay, Rickey

2011-10-01

In this paper, an adaptive control approach based on the neural networks is presented to control a DC motor system with dead-zone characteristics (DZC), where two neural networks are proposed to formulate the traditional identification and control approaches. First, a Wiener-type neural network (WNN) is proposed to identify the motor DZC, which formulates the Wiener model with a linear dynamic block in cascade with a nonlinear static gain. Second, a feedforward neural network is proposed to formulate the traditional PID controller, termed as PID-type neural network (PIDNN), which is then used to control and compensate for the DZC. In this way, the DC motor system with DZC is identified by the WNN identifier, which provides model information to the PIDNN controller in order to make it adaptive. Back-propagation algorithms are used to train both neural networks. Also, stability and convergence analysis are conducted using the Lyapunov theorem. Finally, experiments on the DC motor system demonstrated accurate identification and good compensation for dead-zone with improved control performance over the conventional PID control. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

GeneNetWeaver: in silico benchmark generation and performance profiling of network inference methods.

Science.gov (United States)

Schaffter, Thomas; Marbach, Daniel; Floreano, Dario

2011-08-15

Over the last decade, numerous methods have been developed for inference of regulatory networks from gene expression data. However, accurate and systematic evaluation of these methods is hampered by the difficulty of constructing adequate benchmarks and the lack of tools for a differentiated analysis of network predictions on such benchmarks. Here, we describe a novel and comprehensive method for in silico benchmark generation and performance profiling of network inference methods available to the community as an open-source software called GeneNetWeaver (GNW). In addition to the generation of detailed dynamical models of gene regulatory networks to be used as benchmarks, GNW provides a network motif analysis that reveals systematic prediction errors, thereby indicating potential ways of improving inference methods. The accuracy of network inference methods is evaluated using standard metrics such as precision-recall and receiver operating characteristic curves. We show how GNW can be used to assess the performance and identify the strengths and weaknesses of six inference methods. Furthermore, we used GNW to provide the international Dialogue for Reverse Engineering Assessments and Methods (DREAM) competition with three network inference challenges (DREAM3, DREAM4 and DREAM5). GNW is available at http://gnw.sourceforge.net along with its Java source code, user manual and supporting data. Supplementary data are available at Bioinformatics online. dario.floreano@epfl.ch.

Characteristics of file sharing and peer to peer networking | Opara ...

African Journals Online (AJOL)

Characteristics of file sharing and peer to peer networking. ... distributing or providing access to digitally stored information, such as computer programs, ... including in multicast systems, anonymous communications systems, and web caches.

Characteristic imsets for learning Bayesian network structure

Czech Academy of Sciences Publication Activity Database

Hemmecke, R.; Lindner, S.; Studený, Milan

2012-01-01

Roč. 53, č. 9 (2012), s. 1336-1349 ISSN 0888-613X R&D Projects: GA MŠk(CZ) 1M0572; GA ČR GA201/08/0539 Institutional support: RVO:67985556 Keywords : learning Bayesian network structure * essential graph * standard imset * characteristic imset * LP relaxation of a polytope Subject RIV: BA - General Mathematics Impact factor: 1.729, year: 2012 http://library.utia.cas.cz/separaty/2012/MTR/studeny-0382596.pdf

Depth-dependent flow and pressure characteristics in cortical microvascular networks.

Directory of Open Access Journals (Sweden)

Franca Schmid

2017-02-01

Full Text Available A better knowledge of the flow and pressure distribution in realistic microvascular networks is needed for improving our understanding of neurovascular coupling mechanisms and the related measurement techniques. Here, numerical simulations with discrete tracking of red blood cells (RBCs are performed in three realistic microvascular networks from the mouse cerebral cortex. Our analysis is based on trajectories of individual RBCs and focuses on layer-specific flow phenomena until a cortical depth of 1 mm. The individual RBC trajectories reveal that in the capillary bed RBCs preferentially move in plane. Hence, the capillary flow field shows laminar patterns and a layer-specific analysis is valid. We demonstrate that for RBCs entering the capillary bed close to the cortical surface (< 400 μm the largest pressure drop takes place in the capillaries (37%, while for deeper regions arterioles are responsible for 61% of the total pressure drop. Further flow characteristics, such as capillary transit time or RBC velocity, also vary significantly over cortical depth. Comparison of purely topological characteristics with flow-based ones shows that a combined interpretation of topology and flow is indispensable. Our results provide evidence that it is crucial to consider layer-specific differences for all investigations related to the flow and pressure distribution in the cortical vasculature. These findings support the hypothesis that for an efficient oxygen up-regulation at least two regulation mechanisms must be playing hand in hand, namely cerebral blood flow increase and microvascular flow homogenization. However, the contribution of both regulation mechanisms to oxygen up-regulation likely varies over depth.

Improving the performance of neutral network in differentiation of breast tumors using wavelet transformation on dynamic MRI

International Nuclear Information System (INIS)

Abdolmaleki, P.; Abrishami-Moghddam, H.; Gity, M.; Mokhtari- Dizaji, M.; Mostafa, A.

2005-01-01

A computer aided diagnosis system was established using the wavelet transform and neural network to differentiate malignant from benign in a group of patients with histo-pathologically proved breast lesions based on the data derived independently from time-intensity profile. Materials and Methods: The performance of the artificial neural network was evaluated using a database with 105 patients' records each of which consisted of 8 quantitative parameters mostly derived from time- intensity profile using wavelet transform. These findings were encoded as features for a three-layered neural network to predict the outcome of biopsy. The network was trained and tested using the jackknife method and its performance was then compared to that of the radiologists in terms of sensitivity, specificity and accuracy using receiver operating characteristic curve (ROC) analysis. Results: The network was able to classify correctly the 84 original cases and yielded a comparable diagnostic accuracy (80%), compared to that of the radiologist (85%) by performing a constructive association between extracted quantitative data and corresponding pathological results (r=0.63, p<0.001). Conclusion: An artificial neural network supported by wavelet transform can be trained to differentiate malignant from benign breast tumors with a reasonable degree of accuracy

In-Network Performance of Handheld Mobile Terminals

DEFF Research Database (Denmark)

Nielsen, Jesper Ødum; Pedersen, Gert Frølund

2006-01-01

are compared with the equivalent performance obtained in a live GSM network using data from the Abis network interface. This method does not require altering of the handsets and the testing uses normal calls in the network. The investigation is based on measurements with four different commercially available...

Characteristics of Key Update Strategies for Wireless Sensor Networks

DEFF Research Database (Denmark)

Yuksel, Ender; Nielson, Hanne Riis; Nielson, Flemming

2011-01-01

Wireless sensor networks offer the advantages of simple and low-resource communication. Challenged by this simplicity and low-resources, security is of particular importance in many cases such as transmission of sensitive data or strict requirements of tamper-resistance. Updating the security keys...... is one of the essential points in security, which restrict the amount of data that may be exposed when a key is compromised. In this paper, we investigate key update methods that may be used in wireless sensor networks, and benefiting from stochastic model checking we derive characteristics...

Network performance of a wireless sensor network for temperature monitoring in vineyards

DEFF Research Database (Denmark)

Liscano, Ramiro; Jacoub, John Khalil; Dersingh, Anand

2011-01-01

Wireless sensor networks (WSNs) are an emerging technology which can be used for outdoor environmental monitoring. This paper presents challenges that arose from the development and deployment of a WSN for environmental monitoring as well as network performance analysis of this network. Different...... components in our sensor network architecture are presented like the physical nodes, the sensor node code, and two messaging protocols; one for collecting sensor and network values and the other for sensor node commands. An information model for sensor nodes to support plug-and-play capabilities in sensor...... networks is also presented....

A multihop key agreement scheme for wireless ad hoc networks based on channel characteristics.

Science.gov (United States)

Hao, Zhuo; Zhong, Sheng; Yu, Nenghai

2013-01-01

A number of key agreement schemes based on wireless channel characteristics have been proposed recently. However, previous key agreement schemes require that two nodes which need to agree on a key are within the communication range of each other. Hence, they are not suitable for multihop wireless networks, in which nodes do not always have direct connections with each other. In this paper, we first propose a basic multihop key agreement scheme for wireless ad hoc networks. The proposed basic scheme is resistant to external eavesdroppers. Nevertheless, this basic scheme is not secure when there exist internal eavesdroppers or Man-in-the-Middle (MITM) adversaries. In order to cope with these adversaries, we propose an improved multihop key agreement scheme. We show that the improved scheme is secure against internal eavesdroppers and MITM adversaries in a single path. Both performance analysis and simulation results demonstrate that the improved scheme is efficient. Consequently, the improved key agreement scheme is suitable for multihop wireless ad hoc networks.

Attentional Performance is Correlated with the Local Regional Efficiency of Intrinsic Brain Networks

Directory of Open Access Journals (Sweden)

Junhai eXu

2015-07-01

Full Text Available Attention is a crucial brain function for human beings. Using neuropsychological paradigms and task-based functional brain imaging, previous studies have indicated that widely distributed brain regions are engaged in three distinct attention subsystems: alerting, orienting and executive control (EC. Here, we explored the potential contribution of spontaneous brain activity to attention by examining whether resting-state activity could account for individual differences of the attentional performance in normal individuals. The resting-state functional images and behavioral data from attention network test (ANT task were collected in 59 healthy subjects. Graph analysis was conducted to obtain the characteristics of functional brain networks and linear regression analyses were used to explore their relationships with behavioral performances of the three attentional components. We found that there was no significant relationship between the attentional performance and the global measures, while the attentional performance was associated with specific local regional efficiency. These regions related to the scores of alerting, orienting and EC largely overlapped with the regions activated in previous task-related functional imaging studies, and were consistent with the intrinsic dorsal and ventral attention networks (DAN/VAN. In addition, the strong associations between the attentional performance and specific regional efficiency suggested that there was a possible relationship between the DAN/VAN and task performances in the ANT. We concluded that the intrinsic activity of the human brain could reflect the processing efficiency of the attention system. Our findings revealed a robust evidence for the functional significance of the efficiently organized intrinsic brain network for highly productive cognitions and the hypothesized role of the DAN/ VAN at rest.

Structure of Small World Innovation Network and Learning Performance

Directory of Open Access Journals (Sweden)

Shuang Song

2014-01-01

Full Text Available This paper examines the differences of learning performance of 5 MNCs (multinational corporations that filed the largest number of patents in China. We establish the innovation network with the patent coauthorship data by these 5 MNCs and classify the networks by the tail of distribution curve of connections. To make a comparison of the learning performance of these 5 MNCs with differing network structures, we develop an organization learning model by regarding the reality as having m dimensions, which denotes the heterogeneous knowledge about the reality. We further set n innovative individuals that are mutually interactive and own unique knowledge about the reality. A longer (shorter distance between the knowledge of the individual and the reality denotes a lower (higher knowledge level of that individual. Individuals interact with and learn from each other within the small-world network. By making 1,000 numerical simulations and averaging the simulated results, we find that the differing structure of the small-world network leads to the differences of learning performance between these 5 MNCs. The network monopolization negatively impacts and network connectivity positively impacts learning performance. Policy implications in the conclusion section suggest that to improve firm learning performance, it is necessary to establish a flat and connective network.

Dismissing attachment characteristics dynamically modulate brain networks subserving social aversion.

Directory of Open Access Journals (Sweden)

Anna Linda eKrause

2016-03-01

Full Text Available Attachment patterns influence actions, thoughts and feeling through a person’s ‘Inner Working Model’. Speech charged with attachment-dependent content was proposed to modulate the activation of cognitive-emotional schemata in listeners. We performed a 7 Tesla rest-task-rest fMRI-experiment, presenting auditory narratives prototypical of dismissing attachment representations to investigate their effect on 23 healthy males. We then examined effects of participants’ attachment style and childhood trauma on brain state changes using seed-based functional connectivity (FC analyses, and finally tested whether subjective differences in responsivity to narratives could be predicted by baseline network states. In comparison to a baseline state, we observed increased FC in a previously described ‘social aversion network’ including dorsal anterior cingulated cortex (dACC and left anterior middle temporal gyrus (aMTG specifically after exposure to insecure-dismissing attachment narratives. Increased dACC-seeded FC within the social aversion network was positively related to the participants’ avoidant attachment style and presence of a history of childhood trauma. Anxious attachment style on the other hand was positively correlated with FC between the dACC and a region outside of the ‘social aversion network’, namely the dorsolateral prefrontal cortex, which suggests decreased network segregation as a function of anxious attachment. Finally, the extent of subjective experience of friendliness towards the dismissing narrative was predicted by low baseline FC-values between hippocampus and inferior parietal lobule. Taken together, our study demonstrates an activation of networks related to social aversion in terms of increased connectivity after listening to insecure-dismissing attachment narratives. A causal interrelation of brain state changes and subsequent changes in social reactivity was further supported by our observation of direct

Scholastic performance and functional connectivity of brain networks in children.

Directory of Open Access Journals (Sweden)

Laura Chaddock-Heyman

Full Text Available One of the keys to understanding scholastic success is to determine the neural processes involved in school performance. The present study is the first to use a whole-brain connectivity approach to explore whether functional connectivity of resting state brain networks is associated with scholastic performance in seventy-four 7- to 9-year-old children. We demonstrate that children with higher scholastic performance across reading, math and language have more integrated and interconnected resting state networks, specifically the default mode network, salience network, and frontoparietal network. To add specificity, core regions of the dorsal attention and visual networks did not relate to scholastic performance. The results extend the cognitive role of brain networks in children as well as suggest the importance of network connectivity in scholastic success.

Application of Butterfly Clos-Network in Network-on-Chip

Directory of Open Access Journals (Sweden)

Hui Liu

2014-01-01

Full Text Available This paper studied the topology of NoC (Network-on-Chip. By combining the characteristics of the Clos network and butterfly network, a new topology named BFC (Butterfly Clos-network network was proposed. This topology integrates several modules, which belongs to the same layer but different dimensions, into a new module. In the BFC network, a bidirectional link is used to complete information exchange, instead of information exchange between different layers in the original network. During the routing period, other nondestination nodes can be used as middle stages to transfer data packets to complete the routing mission. Therefore, this topology has the characteristic of multistage. Simulation analyses show that BFC inherits the rich path diversity of Clos network, and it has a better performance than butterfly network in throughput and delay in a quite congested traffic pattern.

Enhancing neural-network performance via assortativity

International Nuclear Information System (INIS)

Franciscis, Sebastiano de; Johnson, Samuel; Torres, Joaquin J.

2011-01-01

The performance of attractor neural networks has been shown to depend crucially on the heterogeneity of the underlying topology. We take this analysis a step further by examining the effect of degree-degree correlations - assortativity - on neural-network behavior. We make use of a method recently put forward for studying correlated networks and dynamics thereon, both analytically and computationally, which is independent of how the topology may have evolved. We show how the robustness to noise is greatly enhanced in assortative (positively correlated) neural networks, especially if it is the hub neurons that store the information.

Developing countries SMEs innovation characteristics and performance

DEFF Research Database (Denmark)

Vang, Jan; Rezaei, Shahamak; Baklanov, Nikita

An econometric study analysing developing countries’ SMEs innovation characteristics and their correlation with performance.......An econometric study analysing developing countries’ SMEs innovation characteristics and their correlation with performance....

Networks, Micro Small Enterprises (MSE'S) and Performance: the ...

African Journals Online (AJOL)

Networks, Micro Small Enterprises (MSE'S) and Performance: the Case of Kenya. ... It adopts the network perspective theoretical approach. Empirically, the ... entrepreneurial personal network as a copying strategy in the process of global

Characteristics of the TRISTAN control computer network

International Nuclear Information System (INIS)

Kurokawa, Shinichi; Akiyama, Atsuyoshi; Katoh, Tadahiko; Kikutani, Eiji; Koiso, Haruyo; Oide, Katsunobu; Shinomoto, Manabu; Kurihara, Michio; Abe, Kenichi

1986-01-01

Twenty-four minicomputers forming an N-to-N token-ring network control the TRISTAN accelerator complex. The computers are linked by optical fiber cables with 10 Mbps transmission speed. The software system is based on NODAL, a multicomputer interpretive language developed at the CERN SPS. The high-level services offered to the users of the network are remote execution by the EXEC, EXEC-P and IMEX commands of NODAL and uniform file access throughout the system. The network software was designed to achieve the fast response of the EXEC command. The performance of the network is also reported. Tasks that overload the minicomputers are processed on the KEK central computers. One minicomputer in the network serves as a gateway to KEKNET, which connects the minicomputer network and the central computers. The communication with the central computers is managed within the framework of the KEK NODAL system. NODAL programs communicate with the central computers calling NODAL functions; functions for exchanging data between a data set on the central computers and a NODAL variable, submitting a batch job to the central computers, checking the status of the submitted job, etc. are prepared. (orig.)

Drive Control Scheme of Electric Power Assisted Wheelchair Based on Neural Network Learning of Human Wheelchair Operation Characteristics

Science.gov (United States)

Tanohata, Naoki; Seki, Hirokazu

This paper describes a novel drive control scheme of electric power assisted wheelchairs based on neural network learning of human wheelchair operation characteristics. “Electric power assisted wheelchair” which enhances the drive force of the operator by employing electric motors is expected to be widely used as a mobility support system for elderly and disabled people. However, some handicapped people with paralysis of the muscles of one side of the body cannot maneuver the wheelchair as desired because of the difference in the right and left input force. Therefore, this study proposes a neural network learning system of such human wheelchair operation characteristics and a drive control scheme with variable distribution and assistance ratios. Some driving experiments will be performed to confirm the effectiveness of the proposed control system.

Fault diagnosis and performance evaluation for high current LIA based on radial basis function neural network

International Nuclear Information System (INIS)

Yang Xinglin; Wang Huacen; Chen Nan; Dai Wenhua; Li Jin

2006-01-01

High current linear induction accelerator (LIA) is a complicated experimental physics device. It is difficult to evaluate and predict its performance. this paper presents a method which combines wavelet packet transform and radial basis function (RBF) neural network to build fault diagnosis and performance evaluation in order to improve reliability of high current LIA. The signal characteristics vectors which are extracted based on energy parameters of wavelet packet transform can well present the temporal and steady features of pulsed power signal, and reduce data dimensions effectively. The fault diagnosis system for accelerating cell and the trend classification system for the beam current based on RBF networks can perform fault diagnosis and evaluation, and provide predictive information for precise maintenance of high current LIA. (authors)

Impact Of Firewall On Network Performance

Directory of Open Access Journals (Sweden)

Francis Kwadzo Agbenyegah

2017-03-01

Full Text Available This research work investigated the firewall security and performance relationship for distributed systems. Internet connectivity is growing with most enterprises migrating to the use of web based services for services provision. As organization grab the Internet as another business tool whether to sell to team up or to communicate - web applications have turned into the new weakest connection in the organizations security technique. Firewalls provide a mechanism for protecting these enterprises from the less secure internet over which customers or collaborating partners transfer packets destined for the corporate network. The connection between the security and execution proficiency is exhibited through distinctive scenarios and the relationship between security and performance in firewalls is assessed. We demonstrated distinctive networks with and without firewalls and diverse firewall functionality and simulated such systems with an eye on their performance. The simulation was done for 300 work stations and simulated in a way that all the 300 work stations access an email and web application under three different scenarios. Attention is on the relationship between system security and performance the impacts of firewalls on system execution. Different scenarios were assessed through simulations utilizing OPNET IT Guru Academic Edition 9.1 to demonstrate the impacts of firewalls on system performance. The result shows that maintaining security which involves the utilization of numerous applications and the use of firewall has an effect on network performance.

Network Signaling Channel for Improving ZigBee Performance in Dynamic Cluster-Tree Networks

Directory of Open Access Journals (Sweden)

D. Hämäläinen

2008-03-01

Full Text Available ZigBee is one of the most potential standardized technologies for wireless sensor networks (WSNs. Yet, sufficient energy-efficiency for the lowest power WSNs is achieved only in rather static networks. This severely limits the applicability of ZigBee in outdoor and mobile applications, where operation environment is harsh and link failures are common. This paper proposes a network channel beaconing (NCB algorithm for improving ZigBee performance in dynamic cluster-tree networks. NCB reduces the energy consumption of passive scans by dedicating one frequency channel for network beacon transmissions and by energy optimizing their transmission rate. According to an energy analysis, the power consumption of network maintenance operations reduces by 70%–76% in dynamic networks. In static networks, energy overhead is negligible. Moreover, the service time for data routing increases up to 37%. The performance of NCB is validated by ns-2 simulations. NCB can be implemented as an extension on MAC and NWK layers and it is fully compatible with ZigBee.

A diagnosis model for early Tourette syndrome children based on brain structural network characteristics

Science.gov (United States)

Wen, Hongwei; Liu, Yue; Wang, Jieqiong; Zhang, Jishui; Peng, Yun; He, Huiguang

2016-03-01

Tourette syndrome (TS) is a childhood-onset neurobehavioral disorder characterized by the presence of multiple motor and vocal tics. Tic generation has been linked to disturbed networks of brain areas involved in planning, controlling and execution of action. The aim of our work is to select topological characteristics of structural network which were most efficient for estimating the classification models to identify early TS children. Here we employed the diffusion tensor imaging (DTI) and deterministic tractography to construct the structural networks of 44 TS children and 48 age and gender matched healthy children. We calculated four different connection matrices (fiber number, mean FA, averaged fiber length weighted and binary matrices) and then applied graph theoretical methods to extract the regional nodal characteristics of structural network. For each weighted or binary network, nodal degree, nodal efficiency and nodal betweenness were selected as features. Support Vector Machine Recursive Feature Extraction (SVM-RFE) algorithm was used to estimate the best feature subset for classification. The accuracy of 88.26% evaluated by a nested cross validation was achieved on combing best feature subset of each network characteristic. The identified discriminative brain nodes mostly located in the basal ganglia and frontal cortico-cortical networks involved in TS children which was associated with tic severity. Our study holds promise for early identification and predicting prognosis of TS children.

Social networks and performance in distributed learning communities

OpenAIRE

Cadima, Rita; Ojeda Rodríguez, Jordi; Monguet Fierro, José María

2012-01-01

Social networks play an essential role in learning environments as a key channel for knowledge sharing and students' support. In distributed learning communities, knowledge sharing does not occur as spontaneously as when a working group shares the same physical space; knowledge sharing depends even more on student informal connections. In this study we analyse two distributed learning communities' social networks in order to understand how characteristics of the social structure can enhance s...

Improved PPP Ambiguity Resolution Considering the Stochastic Characteristics of Atmospheric Corrections from Regional Networks

Science.gov (United States)

Li, Yihe; Li, Bofeng; Gao, Yang

2015-01-01

With the increased availability of regional reference networks, Precise Point Positioning (PPP) can achieve fast ambiguity resolution (AR) and precise positioning by assimilating the satellite fractional cycle biases (FCBs) and atmospheric corrections derived from these networks. In such processing, the atmospheric corrections are usually treated as deterministic quantities. This is however unrealistic since the estimated atmospheric corrections obtained from the network data are random and furthermore the interpolated corrections diverge from the realistic corrections. This paper is dedicated to the stochastic modelling of atmospheric corrections and analyzing their effects on the PPP AR efficiency. The random errors of the interpolated corrections are processed as two components: one is from the random errors of estimated corrections at reference stations, while the other arises from the atmospheric delay discrepancies between reference stations and users. The interpolated atmospheric corrections are then applied by users as pseudo-observations with the estimated stochastic model. Two data sets are processed to assess the performance of interpolated corrections with the estimated stochastic models. The results show that when the stochastic characteristics of interpolated corrections are properly taken into account, the successful fix rate reaches 93.3% within 5 min for a medium inter-station distance network and 80.6% within 10 min for a long inter-station distance network. PMID:26633400

MODEL OF EMERGENCY DEPARTMENT NURSE PERFORMANCE IMPROVEMENT BASED ON ASSOCIATION OF INDIVIDUAL CHARACTERISTIC, ORGANIZATION CHARACTERISTIC AND JOB CHARACTERISTIC

Directory of Open Access Journals (Sweden)

Maria Margaretha Bogar

2017-04-01

Full Text Available Introduction: Nursing care is integral part of health care and having important role in management of patient with emergency condition. The purpose of this research was to develop nurse performance improvement model based on individual, organization and job characteristics association in Emergency Department of RSUD dr TC Hillers Maumere. Method: This was an explanative survey by cross sectional approach held on July -August 2012. Respondents in this study were 22 nurses and 44 patients were obtained by purposive sampling technique. Data were analyzed by partial least square test and signi fi cant t value > 1.64 (alpha 10%. Result: Results showed that individual characteristic had effect on nurse performance (t = 7.59, organization characteristic had effect on nurse performance (t = 2.03 and job characteristic didn’t have effect on nurse performance (t = 0.88. Nurse performance had effect on patient satisfaction (t = 6.54 but nurse satisfaction didn’t have effect on nurse performance (t = 1.31, and nurse satisfaction didn’t have effect either on patient satisfaction (t = 0.94. Discussion: This research concluded that individual characteristics which in fl uence nurse performance in nursing care were ability and skill, experience, age, sex, attitude and motivation. Organization characteristic that influence nurse performance was reward while job characteristic that include job design and feedback didn’t influence nurse performance in nursing care. Nurse performance influenced patient satisfaction but nurse satisfaction didn’t influence patient satisfaction and nurse performance.

Wireless Local Area Network Performance Inside Aircraft Passenger Cabins

Science.gov (United States)

Whetten, Frank L.; Soroker, Andrew; Whetten, Dennis A.; Whetten, Frank L.; Beggs, John H.

2005-01-01

An examination of IEEE 802.11 wireless network performance within an aircraft fuselage is performed. This examination measured the propagated RF power along the length of the fuselage, and the associated network performance: the link speed, total throughput, and packet losses and errors. A total of four airplanes: one single-aisle and three twin-aisle airplanes were tested with 802.11a, 802.11b, and 802.11g networks.

Ethernet image communication performance in a multimodal PACS network

International Nuclear Information System (INIS)

Lou, S.L.; Valentino, D.J.; Chan, K.K.; Huang, H.K.

1989-01-01

The authors have evaluated the performance of an Ethernet network in a multimodal picture archiving and communications system (PACS) environment. The study included measurements between Sun workstations and PC- AT computers running communication software at the TCP level. First they initiated image transfers between two workstations, a server and a client. Next, they successively added clients to transfer images to the server and they measured degradation in network performance. Finally, they initiated image transfers between pairs of workstations and again measured performance degradation. The results of the authors' experiments indicate that Ethernet is suitable for image communication only in limited network situations. They discuss how to maximize network performance given these constraints

Board characteristics, governance objectives, and hospital performance

DEFF Research Database (Denmark)

Thiel, Andrea; Winter, Vera; Büchner, Vera Antonia

2018-01-01

membership relates to board characteristics and financial performance. METHODOLOGY: Using factor analysis, we identify latent classes of governance objectives and use hierarchical cluster analysis to detect distinct clusters with varying emphasis on the classes. We then use multinomial regression to explore...... the associations between cluster membership and board characteristics (size, gender diversity, and occupational diversity) and examine the associations between clusters and financial performance using OLS regression. RESULTS: Classes of objectives reflecting three governance theories-agency theory, stewardship...... and hospital financial performance, with two of three groups performing significantly better than the reference group. CONCLUSION: High performance in hospitals can be the result of governance logics, which, compared to simple board characteristics, are associated with better financial outcomes. PRACTICE...

Outlining the benefits of Strategic Networking

Directory of Open Access Journals (Sweden)

Eva Maria Eckenhofer

2011-10-01

Full Text Available Social Networks have attracted enormous interest in the scientific community in recent years. The characteristics, components and impacts of social networks have been studied through different kinds of aspects, such as sociological, geographical, ethnological, political and economical. In economics social network studies have been performed on intra- and inter-organizational levels, though rarely simultaneously. Furthermore the strategic aspects of fostering and controlling informal organizational networks as well as the outcomes of these managerial attempts on the network characteristics and the performance of the organization have not been sufficiently studied yet. However, the need to develop, foster and manage networks efficiently is given for preventing negative effects and provoking positive ones. Therefore this study contributes to scientific theory and practical business development by exploring the influence of Strategic Networking in inter- as well as intra-organizational business-fields. For study the author develops and defines Strategic Networking as the strategic and target-oriented analysis, development, fostering and control of (inter- as well as intra-organizational networks on the basis of trust, with the intention to reach certain (organizational goals and tests its applicability and effects in an extensive survey on three levels: intra-, inter-organizational and regional networks (cluster. The survey showed that Strategic Networking goes in line with favourable network characteristics as well as the success of a firm in terms of financial and non-financial performance measures.

Artificial neural network approach to predicting engine-out emissions and performance parameters of a turbo charged diesel engine

Directory of Open Access Journals (Sweden)

Özener Orkun

2013-01-01

Full Text Available This study details the artificial neural network (ANN modelling of a diesel engine to predict the torque, power, brake-specific fuel consumption and pollutant emissions, including carbon dioxide, carbon monoxide, nitrogen oxides, total hydrocarbons and filter smoke number. To collect data for training and testing the neural network, experiments were performed on a four cylinder, four stroke compression ignition engine. A total of 108 test points were run on a dynamometer. For the first part of this work, a parameter packet was used as the inputs for the neural network, and satisfactory regression was found with the outputs (over ~95%, excluding total hydrocarbons. The second stage of this work addressed developing new networks with additional inputs for predicting the total hydrocarbons, and the regression was raised from 75 % to 90 %. This study shows that the ANN approach can be used for accurately predicting characteristic values of an internal combustion engine and that the neural network performance can be increased using additional related input data.

Optimizing the ASC WAN: evaluating network performance tools for comparing transport protocols.

Energy Technology Data Exchange (ETDEWEB)

Lydick, Christopher L.

2007-07-01

The Advanced Simulation & Computing Wide Area Network (ASC WAN), which is a high delay-bandwidth network connection between US Department of Energy National Laboratories, is constantly being examined and evaluated for efficiency. One of the current transport-layer protocols which is used, TCP, was developed for traffic demands which are different from that on the ASC WAN. The Stream Control Transport Protocol (SCTP), on the other hand, has shown characteristics which make it more appealing to networks such as these. Most important, before considering a replacement for TCP on any network, a testing tool that performs well against certain criteria needs to be found. In order to try to find such a tool, two popular networking tools (Netperf v.2.4.3 & v.2.4.6 (OpenSS7 STREAMS), and Iperf v.2.0.6) were tested. These tools implement both TCP and SCTP and were evaluated using four metrics: (1) How effectively can the tool reach a throughput near the bandwidth? (2) How much of the CPU does the tool utilize during operation? (3) Is the tool freely and widely available? And, (4) Is the tool actively developed? Following the analysis of those tools, this paper goes further into explaining some recommendations and ideas for future work.

Performance of networks of artificial neurons: The role of clustering

International Nuclear Information System (INIS)

Kim, Beom Jun

2004-01-01

The performance of the Hopfield neural network model is numerically studied on various complex networks, such as the Watts-Strogatz network, the Barabasi-Albert network, and the neuronal network of Caenorhabditis elegans. Through the use of a systematic way of controlling the clustering coefficient, with the degree of each neuron kept unchanged, we find that the networks with the lower clustering exhibit much better performance. The results are discussed in the practical viewpoint of application, and the biological implications are also suggested

Force10 networks performance in world's first transcontinental 10 gigabit ethernet network verified by Ixia

CERN Multimedia

2003-01-01

Force10 Networks, Inc., today announced that the performance of the Force10 E-Series switch/routers deployed in a transcontinental network has been verified as line-rate 10 GE throughput by Ixia, a leading provider of high-speed, network performance and conformance analysis systems. The network, the world's first transcontinental 10 GE wide area network, consists of a SURFnet OC-192 lambda between Geneva and the StarLight facility in Chicago via Amsterdam and another OC-192 lambda between this same facility in Chicago and Carleton University in Ottawa, Canada provided by CANARIE and ORANO (1/2 page).

Network performance and fault analytics for LTE wireless service providers

CERN Document Server

Kakadia, Deepak; Gilgur, Alexander

2017-01-01

 This book is intended to describe how to leverage emerging technologies big data analytics and SDN, to address challenges specific to LTE and IP network performance and fault management data in order to more efficiently manage and operate an LTE wireless networks. The proposed integrated solutions permit the LTE network service provider to operate entire integrated network, from RAN to Core , from UE to application service, as one unified system and correspondingly collect and align disparate key metrics and data, using an integrated and holistic approach to network analysis. The LTE wireless network performance and fault involves the network performance and management of network elements in EUTRAN, EPC and IP transport components, not only as individual components, but also as nuances of inter-working of these components. The key metrics for EUTRAN include radio access network accessibility, retainability, integrity, availability and mobility. The key metrics for EPC include MME accessibility, mobility and...

Network Characteristics, Perceived Social Support, and Psychological Adjustment in Mothers of Children with Autism Spectrum Disorder

Science.gov (United States)

Benson, Paul R.

2012-01-01

This study examined the characteristics of the support networks of 106 mothers of children with ASD and their relationship to perceived social support, depressed mood, and subjective well-being. Using structural equation modeling, two competing sets of hypotheses were assessed: (1) that network characteristics would impact psychological adjustment…

Hamlet, Performance and Chaotic Cultural Networks

Directory of Open Access Journals (Sweden)

Emil Rybczak

2015-10-01

Full Text Available Since the 1960s, chaos theory has become an important but controversial tool used by scientists and mathematicians to describe physical or theoretical systems or networks. It explains how the simple can generate the complex. Its central tenets can also provide an alternative language and means of literary interpretation. This article will explore how the principles of chaos theory can be used to close read and systematise various aspects of the language and performance of Shakespeare. The argument is built upon an analysis of Hamlet, in an effort to understand the play and its reproduction as the evolution of interconnected complex networks. Various aspects of the text will be discussed, including its language, structural and character patterning, and its reproduction through performance and cinematic adaptation. Each of these topics, and the characters, devices or ideas they discuss, constitute nodes of the complex network of Hamlet as both text and idea. Responding to the cultural analysis of other scholars, this article uses Hamlet as an ideal example of how the appropriation of scientific language can defamiliarise a particular literary or dramatic artefact. This allows fresh interpretation and understanding of its location within the broader networks of theatre and culture. I suggest the possibilities of close reading literary works through the lens of chaos and suggest how they might be applied and developed in conjunction with other texts, media or performances.

Data center networks topologies, architectures and fault-tolerance characteristics

CERN Document Server

Liu, Yang; Veeraraghavan, Malathi; Lin, Dong; Hamdi, Mounir

2013-01-01

This SpringerBrief presents a survey of data center network designs and topologies and compares several properties in order to highlight their advantages and disadvantages. The brief also explores several routing protocols designed for these topologies and compares the basic algorithms to establish connections, the techniques used to gain better performance, and the mechanisms for fault-tolerance. Readers will be equipped to understand how current research on data center networks enables the design of future architectures that can improve performance and dependability of data centers. This con

Identifying protein complex by integrating characteristic of core-attachment into dynamic PPI network.

Directory of Open Access Journals (Sweden)

Xianjun Shen

Full Text Available How to identify protein complex is an important and challenging task in proteomics. It would make great contribution to our knowledge of molecular mechanism in cell life activities. However, the inherent organization and dynamic characteristic of cell system have rarely been incorporated into the existing algorithms for detecting protein complexes because of the limitation of protein-protein interaction (PPI data produced by high throughput techniques. The availability of time course gene expression profile enables us to uncover the dynamics of molecular networks and improve the detection of protein complexes. In order to achieve this goal, this paper proposes a novel algorithm DCA (Dynamic Core-Attachment. It detects protein-complex core comprising of continually expressed and highly connected proteins in dynamic PPI network, and then the protein complex is formed by including the attachments with high adhesion into the core. The integration of core-attachment feature into the dynamic PPI network is responsible for the superiority of our algorithm. DCA has been applied on two different yeast dynamic PPI networks and the experimental results show that it performs significantly better than the state-of-the-art techniques in terms of prediction accuracy, hF-measure and statistical significance in biology. In addition, the identified complexes with strong biological significance provide potential candidate complexes for biologists to validate.

Information-Theoretic Performance Analysis of Sensor Networks via Markov Modeling of Time Series Data.

Science.gov (United States)

Li, Yue; Jha, Devesh K; Ray, Asok; Wettergren, Thomas A; Yue Li; Jha, Devesh K; Ray, Asok; Wettergren, Thomas A; Wettergren, Thomas A; Li, Yue; Ray, Asok; Jha, Devesh K

2018-06-01

This paper presents information-theoretic performance analysis of passive sensor networks for detection of moving targets. The proposed method falls largely under the category of data-level information fusion in sensor networks. To this end, a measure of information contribution for sensors is formulated in a symbolic dynamics framework. The network information state is approximately represented as the largest principal component of the time series collected across the network. To quantify each sensor's contribution for generation of the information content, Markov machine models as well as x-Markov (pronounced as cross-Markov) machine models, conditioned on the network information state, are constructed; the difference between the conditional entropies of these machines is then treated as an approximate measure of information contribution by the respective sensors. The x-Markov models represent the conditional temporal statistics given the network information state. The proposed method has been validated on experimental data collected from a local area network of passive sensors for target detection, where the statistical characteristics of environmental disturbances are similar to those of the target signal in the sense of time scale and texture. A distinctive feature of the proposed algorithm is that the network decisions are independent of the behavior and identity of the individual sensors, which is desirable from computational perspectives. Results are presented to demonstrate the proposed method's efficacy to correctly identify the presence of a target with very low false-alarm rates. The performance of the underlying algorithm is compared with that of a recent data-driven, feature-level information fusion algorithm. It is shown that the proposed algorithm outperforms the other algorithm.

Performance Analysis of IIUM Wireless Campus Network

International Nuclear Information System (INIS)

Latif, Suhaimi Abd; Masud, Mosharrof H; Anwar, Farhat

2013-01-01

International Islamic University Malaysia (IIUM) is one of the leading universities in the world in terms of quality of education that has been achieved due to providing numerous facilities including wireless services to every enrolled student. The quality of this wireless service is controlled and monitored by Information Technology Division (ITD), an ISO standardized organization under the university. This paper aims to investigate the constraints of wireless campus network of IIUM. It evaluates the performance of the IIUM wireless campus network in terms of delay, throughput and jitter. QualNet 5.2 simulator tool has employed to measure these performances of IIUM wireless campus network. The observation from the simulation result could be one of the influencing factors in improving wireless services for ITD and further improvement

Network characteristics, perceived social support, and psychological adjustment in mothers of children with autism spectrum disorder.

Science.gov (United States)

Benson, Paul R

2012-12-01

This study examined the characteristics of the support networks of 106 mothers of children with ASD and their relationship to perceived social support, depressed mood, and subjective well-being. Using structural equation modeling, two competing sets of hypotheses were assessed: (1) that network characteristics would impact psychological adjustment directly, and (2) that network effects on adjustment would be indirect, mediated by perceived social support. Results primarily lent support to the latter hypotheses, with measures of network structure (network size) and function (proportion of network members providing emotional support) predicting increased levels of perceived social support which, in turn, predicted decreased depressed mood and increased well-being. Results also indicated that increased interpersonal strain in the maternal network was directly and indirectly associated with increased maternal depression, while being indirectly linked to reduced well-being. Study limitations and implications are discussed.

Multiplex network analysis of employee performance and employee social relationships

Science.gov (United States)

Cai, Meng; Wang, Wei; Cui, Ying; Stanley, H. Eugene

2018-01-01

In human resource management, employee performance is strongly affected by both formal and informal employee networks. Most previous research on employee performance has focused on monolayer networks that can represent only single categories of employee social relationships. We study employee performance by taking into account the entire multiplex structure of underlying employee social networks. We collect three datasets consisting of five different employee relationship categories in three firms, and predict employee performance using degree centrality and eigenvector centrality in a superimposed multiplex network (SMN) and an unfolded multiplex network (UMN). We use a quadratic assignment procedure (QAP) analysis and a regression analysis to demonstrate that the different categories of relationship are mutually embedded and that the strength of their impact on employee performance differs. We also use weighted/unweighted SMN/UMN to measure the predictive accuracy of this approach and find that employees with high centrality in a weighted UMN are more likely to perform well. Our results shed new light on how social structures affect employee performance.

The Impact of Message Replication on the Performance of Opportunistic Networks for Sensed Data Collection

Directory of Open Access Journals (Sweden)

Tekenate E. Amah

2017-11-01

Full Text Available Opportunistic networks (OppNets provide a scalable solution for collecting delay‑tolerant data from sensors for their respective gateways. Portable handheld user devices contribute significantly to the scalability of OppNets since their number increases according to user population and they closely follow human movement patterns. Hence, OppNets for sensed data collection are characterised by high node population and degrees of spatial locality inherent to user movement. We study the impact of these characteristics on the performance of existing OppNet message replication techniques. Our findings reveal that the existing replication techniques are not specifically designed to cope with these characteristics. This raises concerns regarding excessive message transmission overhead and throughput degradations due to resource constraints and technological limitations associated with portable handheld user devices. Based on concepts derived from the study, we suggest design guidelines to augment existing message replication techniques. We also follow our design guidelines to propose a message replication technique, namely Locality Aware Replication (LARep. Simulation results show that LARep achieves better network performance under high node population and degrees of spatial locality as compared with existing techniques.

Analysis of interference performance of tactical radio network

Science.gov (United States)

Nie, Hao; Cai, Xiaoxia; Chen, Hong

2017-08-01

Mobile Ad hoc network has a strong military background for its development as the core technology of the backbone network of US tactical Internet. And which tactical radio network, is the war in today's tactical use of the Internet more mature form of networking, mainly used in brigade and brigade following forces. This paper analyzes the typical protocol AODV in the tactical radio network, and then carries on the networking. By adding the interference device to the whole network, the battlefield environment is simulated, and then the throughput, delay and packet loss rate are analyzed, and the performance of the whole network and the single node before and after the interference is obtained.

Study on the complex network characteristics of urban road system based on GIS

Science.gov (United States)

Gao, Zhonghua; Chen, Zhenjie; Liu, Yongxue; Huang, Kang

2007-06-01

Urban road system is the basic bone of urban transportation and one of the most important factors that influent and controls the urban configuration. In this paper, an approach of modeling, analyzing and optimizing urban road system is described based on complex network theory and GIS technology. The urban road system is studied on three focuses: building the urban road network, modeling the computational procedures based on urban road networks and analyzing the urban road system of Changzhou City as the study case. The conclusion is that the urban road network is a scale-free network with small-world characteristic, and there is still space for development of the whole network as a small-world network, also the key road crosses should be kept expedite.

Modeling the Effect of Bandwidth Allocation on Network Performance

African Journals Online (AJOL)

... The proposed model showed improved performance for CDMA networks, but further increase in the bandwidth did not benefit the network; (iii) A reliability measure such as the spectral efficiency is therefore useful to redeem the limitation in (ii). Keywords: Coverage Capacity, CDMA, Mobile Network, Network Throughput ...

A Set of Functional Brain Networks for the Comprehensive Evaluation of Human Characteristics

Directory of Open Access Journals (Sweden)

Yul-Wan Sung

2018-03-01

Full Text Available Many human characteristics must be evaluated to comprehensively understand an individual, and measurements of the corresponding cognition/behavior are required. Brain imaging by functional MRI (fMRI has been widely used to examine brain function related to human cognition/behavior. However, few aspects of cognition/behavior of individuals or experimental groups can be examined through task-based fMRI. Recently, resting state fMRI (rs-fMRI signals have been shown to represent functional infrastructure in the brain that is highly involved in processing information related to cognition/behavior. Using rs-fMRI may allow diverse information about the brain through a single MRI scan to be obtained, as rs-fMRI does not require stimulus tasks. In this study, we attempted to identify a set of functional networks representing cognition/behavior that are related to a wide variety of human characteristics and to evaluate these characteristics using rs-fMRI data. If possible, these findings would support the potential of rs-fMRI to provide diverse information about the brain. We used resting-state fMRI and a set of 130 psychometric parameters that cover most human characteristics, including those related to intelligence and emotional quotients and social ability/skill. We identified 163 brain regions by VBM analysis using regression analysis with 130 psychometric parameters. Next, using a 163 × 163 correlation matrix, we identified functional networks related to 111 of the 130 psychometric parameters. Finally, we made an 8-class support vector machine classifiers corresponding to these 111 functional networks. Our results demonstrate that rs-fMRI signals contain intrinsic information about brain function related to cognition/behaviors and that this set of 111 networks/classifiers can be used to comprehensively evaluate human characteristics.

User-Location Aware Downlink Performance Analysis of LTE Networks

OpenAIRE

Olaifa, John Olorunfemi

2016-01-01

In order to evaluate the performance of Long Term Evolution (LTE) networks, system-level simulation with detailed focus on network related effects such as mobility, scheduling and interference management must be emphasized. Existing studies evaluate user throughput and dimension LTE networks usually assuming uniform distribution of users within the cell. These studies report average user throughputs over the cell and the 5th percentile throughputs as estimates of the performance of the users ...

Assessing the implications of cellular network performance on mobile content access

DEFF Research Database (Denmark)

Kaup, Fabian; Michelinakis, Foivos; Bui, Nicola

2016-01-01

Mobile applications such as VoIP, (live) gaming, or video streaming have diverse QoS requirements ranging from low delay to high throughput. The optimization of the network quality experienced by end-users requires detailed knowledge of the expected network performance. Also, the achieved service...... of cellular network measurements, focused on analyzing root causes of mobile network performance variability. Measurements conducted on a 4G cellular network in Germany show that management and configuration decisions have a substantial impact on the performance. Specifically, it is observed...

Independent and Interactive Effects of Neighborhood Disadvantage and Social Network Characteristics on Problem Drinking after Treatment.

Science.gov (United States)

Mericle, Amy A; Kaskutas, Lee A; Polcin, Doug L; Karriker-Jaffe, Katherine J

2018-01-01

Socioecological approaches to public health problems like addiction emphasize the importance of person-environment interactions. Neighborhood and social network characteristics may influence the likelihood of relapse among individuals in recovery, but these factors have been understudied, particularly with respect to conceptualizing social network characteristics as moderators of neighborhood disadvantage. Drawing from a larger prospective study of individuals recruited from outpatient treatment (N=451) and interviewed 1, 3, 5, and 7 years later, the aim of this study was to examine the independent and interactive effects of neighborhood and social network characteristics on continued problem drinking after treatment. Models using generalized estimating equations controlling for demographic and other risk factors found the number of heavy drinkers in one's network increases risk of relapse, with the effects being significantly stronger among those living in disadvantaged neighborhoods than among those in non-disadvantaged neighborhoods. No independent effects were found for neighborhood disadvantage or for the number of network members supporting reduced drinking. Future research is needed to examine potential protective factors in neighborhoods which may offset socioeconomic disadvantage as well as to investigate the functions that network members serve in helping to improve long-term treatment outcomes.

Investigating the effect of communication characteristics on crew performance under the simulated emergency condition of nuclear power plants

International Nuclear Information System (INIS)

Park, Jinkyun; Jung, Wondea; Yang, Joon-Eon

2012-01-01

It is well known that the safety of large process control systems could be significantly affected by the communication characteristics of crews that have a responsibility for their operations. Accordingly, many researchers have spent huge amount of effort to grasp the relationship between the characteristics of crew communications and the associated crew performance. Unfortunately, in the case of nuclear power plants (NPPs), it seems that most of existing studies have tried to identify the relationship between the characteristics of crew communications and the associated crew performance using empirical observations without a firm technical underpinning. For these reasons, Park suggested a novel framework that is able to represent the characteristics of crew communications based on social network analysis (SNA) metrics. In order to confirm the appropriateness of the suggested framework, in this study, the characteristics of crew communications that are gathered from the simulated emergency condition of NPPs are additionally compared with the associated crew performance data. As a consequence, it is observed that there are significant relationships between communication characteristics and the associated crew performance. Therefore, it is reasonable to expect that the characteristics of crew communications can be properly grasped using the suggested framework. - Highlights: ► Communication data of MCR operating crews are collected from a simulated emergency condition. ► Communication characteristics are represented by the associated SNA metrics. ► Identified communication characteristics are compared with the results of existing studies. ► SNA metrics are meaningful for explaining the characteristics of crew communications.

[Characteristics of social supportive network serving the older female sex workers in Qingdao].

Science.gov (United States)

Xu, Y Q; Li, Y F; Jiang, Z X; Zhang, X J; Yuan, X; Zhang, N; Li, X F; Jiang, B F

2016-02-01

To overview the status of social support on older female sex workers (OFSWs) in Qingdao and to better understand the characteristics of this egocentric social support networks. Ucinet 6 software was used to analyze the characteristics of egocentric social networks which involving 400 OFSWs who were recruited by respondent-driven sampling (RDS) method in Qingdao during March 2014 to June. Structural equation model (SEM) was used for data analysis, fitted test and estimation. A total of 400 OFSWs of Qingdao nominated 1 617 social supportive members, and the average size of egocentric social networks of OFSWs was (4.0 ± 1.5). Among all the alter egos (social support network members of the egos), 613 were female sex workers fellows, accounted for the most important part of all the social ties (37.91%). Characteristics of small size and non-relative relationships were seen more obviously among OFSWs with non-local registration and the ratings of emotional support (4.42±2.38) was significantly lower than the tangible support (5.73 ± 1.69) (Psocial support from friends who were also female sex workers. Stronger the joint strength between egos and alters, greater the homogeneity between the two was seen. Tighter relations among the alter egos, higher degree of average social support of the egos were acquired.

Optical Performance Monitoring and Signal Optimization in Optical Networks

DEFF Research Database (Denmark)

Petersen, Martin Nordal

2006-01-01

The thesis studies performance monitoring for the next generation optical networks. The focus is on all-optical networks with bit-rates of 10 Gb/s or above. Next generation all-optical networks offer large challenges as the optical transmitted distance increases and the occurrence of electrical-optical......-electrical regeneration points decreases. This thesis evaluates the impact of signal degrading effects that are becoming of increasing concern in all-optical high-speed networks due to all-optical switching and higher bit-rates. Especially group-velocity-dispersion (GVD) and a number of nonlinear effects will require...... enhanced attention to avoid signal degradations. The requirements for optical performance monitoring features are discussed, and the thesis evaluates the advantages and necessity of increasing the level of performance monitoring parameters in the physical layer. In particular, methods for optical...

Optical network control plane for multi-domain networking

DEFF Research Database (Denmark)

Manolova, Anna Vasileva

This thesis focuses on multi-domain routing for traffice engineering and survivability support in optical transport networks under the Generalized Multi-Protocol Label Switching (GMPLS) control framework. First, different extensions to the Border Gateway Protocol for multi-domain Traffic...... process are not enough for efficient TE in mesh multi-domain networks. Enhancing the protocol with multi-path dissemination capability, combined with the employment of an end-to-end TE metric proves to be a highly efficient solution. Simulation results show good performance characteristics of the proposed...... is not as essential for improved network performance as the length of the provided paths. Second, the issue of multi-domain survivability support is analyzed. An AS-disjoint paths is beneficial not only for resilience support, but also for facilitating adequate network reactions to changes in the network, which...

Statistical modelling of networked human-automation performance using working memory capacity.

Science.gov (United States)

Ahmed, Nisar; de Visser, Ewart; Shaw, Tyler; Mohamed-Ameen, Amira; Campbell, Mark; Parasuraman, Raja

2014-01-01

This study examines the challenging problem of modelling the interaction between individual attentional limitations and decision-making performance in networked human-automation system tasks. Analysis of real experimental data from a task involving networked supervision of multiple unmanned aerial vehicles by human participants shows that both task load and network message quality affect performance, but that these effects are modulated by individual differences in working memory (WM) capacity. These insights were used to assess three statistical approaches for modelling and making predictions with real experimental networked supervisory performance data: classical linear regression, non-parametric Gaussian processes and probabilistic Bayesian networks. It is shown that each of these approaches can help designers of networked human-automated systems cope with various uncertainties in order to accommodate future users by linking expected operating conditions and performance from real experimental data to observable cognitive traits like WM capacity. Practitioner Summary: Working memory (WM) capacity helps account for inter-individual variability in operator performance in networked unmanned aerial vehicle supervisory tasks. This is useful for reliable performance prediction near experimental conditions via linear models; robust statistical prediction beyond experimental conditions via Gaussian process models and probabilistic inference about unknown task conditions/WM capacities via Bayesian network models.

Structural Modeling and Characteristics Analysis of Flow Interaction Networks in the Internet

International Nuclear Information System (INIS)

Wu Xiao-Yu; Gu Ren-Tao; Pan Zhuo-Ya; Jin Wei-Qi; Ji Yue-Feng

2015-01-01

Applying network duality and elastic mechanics, we investigate the interactions among Internet flows by constructing a weighted undirected network, where the vertices and the edges represent the flows and the mutual dependence between flows, respectively. Based on the obtained flow interaction network, we find the existence of ‘super flow’ in the Internet, indicating that some flows have a great impact on a huge number of other flows; moreover, one flow can spread its influence to another through a limited quantity of flows (less than 5 in the experimental simulations), which shows strong small-world characteristics like the social network. To reflect the flow interactions in the physical network congestion evaluation, the ‘congestion coefficient’ is proposed as a new metric which shows a finer observation on congestion than the conventional one. (paper)

Switching performance of OBS network model under prefetched real traffic

Science.gov (United States)

Huang, Zhenhua; Xu, Du; Lei, Wen

2005-11-01

Optical Burst Switching (OBS) [1] is now widely considered as an efficient switching technique in building the next generation optical Internet .So it's very important to precisely evaluate the performance of the OBS network model. The performance of the OBS network model is variable in different condition, but the most important thing is that how it works under real traffic load. In the traditional simulation models, uniform traffics are usually generated by simulation software to imitate the data source of the edge node in the OBS network model, and through which the performance of the OBS network is evaluated. Unfortunately, without being simulated by real traffic, the traditional simulation models have several problems and their results are doubtable. To deal with this problem, we present a new simulation model for analysis and performance evaluation of the OBS network, which uses prefetched IP traffic to be data source of the OBS network model. The prefetched IP traffic can be considered as real IP source of the OBS edge node and the OBS network model has the same clock rate with a real OBS system. So it's easy to conclude that this model is closer to the real OBS system than the traditional ones. The simulation results also indicate that this model is more accurate to evaluate the performance of the OBS network system and the results of this model are closer to the actual situation.

High Performance Networks for High Impact Science

Energy Technology Data Exchange (ETDEWEB)

Scott, Mary A.; Bair, Raymond A.

2003-02-13

This workshop was the first major activity in developing a strategic plan for high-performance networking in the Office of Science. Held August 13 through 15, 2002, it brought together a selection of end users, especially representing the emerging, high-visibility initiatives, and network visionaries to identify opportunities and begin defining the path forward.

SON for LTE-WLAN access network selection : design and performance

NARCIS (Netherlands)

Willemen, P.; Laselva, D.; Wang, Y.; Kovács, I.; Djapic, R.; Moerman, I.

2016-01-01

Mobile network operators (MNOs) are deploying carrier-grade Wireless Local Area Network (WLAN) as an important complementary system to cellular networks. Access network selection (ANS) between cellular and WLAN is an essential component to improve network performance and user quality-of-service

Bridging Social Circles: Need for Cognition, Prejudicial Judgments, and Personal Social Network Characteristics

Directory of Open Access Journals (Sweden)

Petru L. Curşeu

2017-07-01

Full Text Available Various factors pertaining to the social context (availability of plausible social contacts as well as personality traits influence the emergence of social ties that ultimately compose one’s personal social network. We build on a situational selection model to argue that personality traits influence the cognitive processing of social cues that in turn influences the preference for particular social ties. More specifically, we use a cross-lagged design to test a mediation model explaining the effects of need for cognition (NFC on egocentric network characteristics. We used the data available in the LISS panel, in which a probabilistic sample of Dutch participants were asked to fill in surveys annually. We tested our model on data collected in three successive years and our results show that people scoring high in NFC tend to revolve in information-rich egocentric networks, characterized by high demographic diversity, high interpersonal dissimilarity, and high average education. The results also show that the effect of NFC on social network characteristics is mediated by non-prejudicial judgments.

The performance analysis of linux networking - packet receiving

Energy Technology Data Exchange (ETDEWEB)

Wu, Wenji; Crawford, Matt; Bowden, Mark; /Fermilab

2006-11-01

The computing models for High-Energy Physics experiments are becoming ever more globally distributed and grid-based, both for technical reasons (e.g., to place computational and data resources near each other and the demand) and for strategic reasons (e.g., to leverage equipment investments). To support such computing models, the network and end systems, computing and storage, face unprecedented challenges. One of the biggest challenges is to transfer scientific data sets--now in the multi-petabyte (10{sup 15} bytes) range and expected to grow to exabytes within a decade--reliably and efficiently among facilities and computation centers scattered around the world. Both the network and end systems should be able to provide the capabilities to support high bandwidth, sustained, end-to-end data transmission. Recent trends in technology are showing that although the raw transmission speeds used in networks are increasing rapidly, the rate of advancement of microprocessor technology has slowed down. Therefore, network protocol-processing overheads have risen sharply in comparison with the time spent in packet transmission, resulting in degraded throughput for networked applications. More and more, it is the network end system, instead of the network, that is responsible for degraded performance of network applications. In this paper, the Linux system's packet receive process is studied from NIC to application. We develop a mathematical model to characterize the Linux packet receiving process. Key factors that affect Linux systems network performance are analyzed.

Addressing the Influence of Hidden State on Wireless Network Optimizations using Performance Maps

DEFF Research Database (Denmark)

Højgaard-Hansen, Kim; Madsen, Tatiana Kozlova; Schwefel, Hans-Peter

2015-01-01

be used to optimize the use of the wireless net- work by predicting future network performance and scheduling the net- work communication for certain applications on mobile devices. However, other important factors influence the performance of the wireless communication such as changes in the propagation...... environment and resource sharing. In this work we extend the framework of performance maps for wireless networks by introducing network state as an abstraction for all other factors than location that influence the performance. Since network state might not always be directly observable the framework......Performance of wireless connectivity for network client devices is location dependent. It has been shown that it can be beneficial to collect network performance metrics along with location information to generate maps of the location dependent network performance. These performance maps can...

Correlation between hierarchical structure of crystal networks and macroscopic performance of mesoscopic soft materials and engineering principles.

Science.gov (United States)

Lin, Naibo; Liu, Xiang Yang

2015-11-07

This review examines how the concepts and ideas of crystallization can be extended further and applied to the field of mesoscopic soft materials. It concerns the structural characteristics vs. the macroscopic performance, and the formation mechanism of crystal networks. Although this subject can be discussed in a broad sense across the area of mesoscopic soft materials, our main focus is on supramolecular materials, spider and silkworm silks, and biominerals. First, the occurrence of a hierarchical structure, i.e. crystal network and domain network structures, will facilitate the formation kinetics of mesoscopic phases and boost up the macroscopic performance of materials in some cases (i.e. spider silk fibres). Second, the structure and performance of materials can be correlated in some way by the four factors: topology, correlation length, symmetry/ordering, and strength of association of crystal networks. Moreover, four different kinetic paths of crystal network formation are identified, namely, one-step process of assembly, two-step process of assembly, mixed mode of assembly and foreign molecule mediated assembly. Based on the basic mechanisms of crystal nucleation and growth, the formation of crystal networks, such as crystallographic mismatch (or noncrystallographic) branching (tip branching and fibre side branching) and fibre/polymeric side merging, are reviewed. This facilitates the rational design and construction of crystal networks in supramolecular materials. In this context, the (re-)construction of a hierarchical crystal network structure can be implemented by thermal, precipitate, chemical, and sonication stimuli. As another important class of soft materials, the unusual mechanical performance of spider and silkworm silk fibres are reviewed in comparison with the regenerated silk protein derivatives. It follows that the considerably larger breaking stress and unusual breaking strain of spider silk fibres vs. silkworm silk fibres can be interpreted

TCP Performance Enhancement for UMTS Access Network

DEFF Research Database (Denmark)

Hu, Liang

2008-01-01

is between UMTS access network and Internet. The split proxy divides the bandwidth delay product into two parts, resulting in two TCP connections with smaller bandwidth delay products. Simulation results show, the split TCP proxy can significantly improve the TCP performance under high bit rate DCH channel......We aim at optimize the TCP performance over UMTS access network challenged by the large delay bandwidth product that is mainly caused by the latency from the link layer ARQ retransmissions and diversity technique at physical layer. We propose to place a split TCP proxy at GGSN nodes which...

The Importance of External Contacts in Job Performance: A Study in Healthcare Organizations Using Social Network Analysis

Directory of Open Access Journals (Sweden)

Pilar Marqués-Sánchez

2018-06-01

Full Text Available There is evidence that relations between physicians and nurses within healthcare institutions might be shaped by informal aspects of such relations and by links to people external to the organization, with an impact on work performance. Social network analysis is underutilized in exploring such associations. The paper aims to describe physicians’ and nurses’ relationships outside their clinical units and to explore what kind of ties are related to job performance. A network analysis was performed on cross-sectional data. The study population consisted of 196 healthcare employees working in a public hospital and a primary healthcare centre in Spain. Relational data were analysed using the UCINET software package. Measures included: (i sample characteristics; (ii social network variables; and (iii team performance ratings. Descriptive statistics (means, medians, percentages were used to characterize staff and performance ratings. A correlational analysis was conducted to examine the strength of relationships between four different types of ties. Our findings suggest that external ties only contribute to improving the performance of physicians at both the individual and team level. They are focused on the decision-making process about the therapeutic plan and, therefore, might need to seek advice outside the workplace. In contrast, external ties are not relevant for the work performance of nurses, as they need to find solutions to immediate problems in a short period of time, having strong ties in the workplace. Social network analysis can illuminate relations within healthcare organizations and inform the development of innovative interventions.

Performance Analysis of Congestion Control Mechanism in Software Defined Network (SDN

Directory of Open Access Journals (Sweden)

Rahman M. Z. A.

2017-01-01

Full Text Available In the near future, the traditional networks architecture will be difficult to be managed. Hence, Software Defined Network (SDN will be an alternative in the future of programmable networks to replace the conventional network architecture. The main idea of SDN architecture is to separate the forwarding plane and control plane of network system, where network operators can program packet forwarding behaviour to improve the network performance. Congestion control is important mechanism for network traffic to improve network capability and achieve high end Quality of Service (QoS. In this paper, extensive simulation is conducted to analyse the performance of SDN by implementing Link Layer Discovery Protocol (LLDP under congested network. The simulation was conducted on Mininet by creating four different fanout and the result was analysed based on differences of matrix performance. As a result, the packet loss and throughput reduction were observed when number of fanout in the topology was increased. By using LLDP protocol, huge reduction in packet loss rate has been achieved while maximizing percentage packet delivery ratio.

SME network characteristics vs. product innovativeness: how to achieve high innovation performance

NARCIS (Netherlands)

Pullen, A.J.J.; de Weerd-Nederhof, Petronella C.; Groen, Arend J.; Fisscher, O.A.M.

2012-01-01

Small- and medium-sized enterprises (SMEs) must on the one hand innovate for company survival with the appropriate degree of product innovativeness, and on the other they need to collaborate and focus on core competences for efficiency matters. This research examines the relation of network

Wireless ad hoc and sensor networks management, performance, and applications

CERN Document Server

He, Jing

2013-01-01

Although wireless sensor networks (WSNs) have been employed across a wide range of applications, there are very few books that emphasize the algorithm description, performance analysis, and applications of network management techniques in WSNs. Filling this need, Wireless Ad Hoc and Sensor Networks: Management, Performance, and Applications summarizes not only traditional and classical network management techniques, but also state-of-the-art techniques in this area. The articles presented are expository, but scholarly in nature, including the appropriate history background, a review of current

Classification of Company Performance using Weighted Probabilistic Neural Network

Science.gov (United States)

Yasin, Hasbi; Waridi Basyiruddin Arifin, Adi; Warsito, Budi

2018-05-01

Classification of company performance can be judged by looking at its financial status, whether good or bad state. Classification of company performance can be achieved by some approach, either parametric or non-parametric. Neural Network is one of non-parametric methods. One of Artificial Neural Network (ANN) models is Probabilistic Neural Network (PNN). PNN consists of four layers, i.e. input layer, pattern layer, addition layer, and output layer. The distance function used is the euclidean distance and each class share the same values as their weights. In this study used PNN that has been modified on the weighting process between the pattern layer and the addition layer by involving the calculation of the mahalanobis distance. This model is called the Weighted Probabilistic Neural Network (WPNN). The results show that the company's performance modeling with the WPNN model has a very high accuracy that reaches 100%.

Estimating cellular network performance during hurricanes

International Nuclear Information System (INIS)

Booker, Graham; Torres, Jacob; Guikema, Seth; Sprintson, Alex; Brumbelow, Kelly

2010-01-01

Cellular networks serve a critical role during and immediately after a hurricane, allowing citizens to contact emergency services when land-line communication is lost and serving as a backup communication channel for emergency responders. However, due to their ubiquitous deployment and limited design for extreme loading events, basic network elements, such as cellular towers and antennas are prone to failures during adverse weather conditions such as hurricanes. Accordingly, a systematic and computationally feasible approach is required for assessing and improving the reliability of cellular networks during hurricanes. In this paper we develop a new multi-disciplinary approach to efficiently and accurately assess cellular network reliability during hurricanes. We show how the performance of a cellular network during and immediately after future hurricanes can be estimated based on a combination of hurricane wind field models, structural reliability analysis, Monte Carlo simulation, and cellular network models and simulation tools. We then demonstrate the use of this approach for assessing the improvement in system reliability that can be achieved with discrete topological changes in the system. Our results suggest that adding redundancy, particularly through a mesh topology or through the addition of an optical fiber ring around the perimeter of the system can be an effective way to significantly increase the reliability of some cellular systems during hurricanes.

Hospital network performance: a survey of hospital stakeholders' perspectives.

Science.gov (United States)

Bravi, F; Gibertoni, D; Marcon, A; Sicotte, C; Minvielle, E; Rucci, P; Angelastro, A; Carradori, T; Fantini, M P

2013-02-01

Hospital networks are an emerging organizational form designed to face the new challenges of public health systems. Although the benefits introduced by network models in terms of rationalization of resources are known, evidence about stakeholders' perspectives on hospital network performance from the literature is scanty. Using the Competing Values Framework of organizational effectiveness and its subsequent adaptation by Minvielle et al., we conducted in 2009 a survey in five hospitals of an Italian network for oncological care to examine and compare the views on hospital network performance of internal stakeholders (physicians, nurses and the administrative staff). 329 questionnaires exploring stakeholders' perspectives were completed, with a response rate of 65.8%. Using exploratory factor analysis of the 66 items of the questionnaire, we identified 4 factors, i.e. Centrality of relationships, Quality of care, Attractiveness/Reputation and Staff empowerment and Protection of workers' rights. 42 items were retained in the analysis. Factor scores proved to be high (mean score>8 on a 10-item scale), except for Attractiveness/Reputation (mean score 6.79), indicating that stakeholders attach a higher importance to relational and health care aspects. Comparison of factor scores among stakeholders did not reveal significant differences, suggesting a broadly shared view on hospital network performance. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Environmental investment and firm performance: A network approach

International Nuclear Information System (INIS)

Bostian, Moriah; Färe, Rolf; Grosskopf, Shawna; Lundgren, Tommy

2016-01-01

This study examines the role of investment in environmental production practices for both environmental performance and energy efficiency over time. We employ a network DEA approach that links successive production technologies through intertemporal investment decisions with a period by period estimation. This allows us to estimate energy efficiency and environmental performance separately, as well as productivity change and its associated decompositions into efficiency change and technology change. Incorporating a network model also allows us to account for both short-term environmental management practices and long-term environmental investments in each of our productivity measures. We apply this framework to a panel of detailed plant-level production data for Swedish manufacturing firms covering the years 2002–2008. - Highlights: • We use a network DEA model to account for intertemporal environmental investment decisionsin measures of firm productivity. • We apply our network technology model to a panel of firms in Sweden's pulp and paperindustry for the years 2002 - 2008. • We model environmental investments and expenditures separately from other productionoriented inputs. • We find evidence of positive relationships between energy efficiency, environmental performance, and firm productivity.

An investigation of 'sparse channel networks'. Characteristic behaviours and their causes

International Nuclear Information System (INIS)

Black, J.H.; Barker, J.A.; Woodman, N.D.

2007-09-01

This report represents a third study in a series concerned with groundwater flow in poorly permeable fractured crystalline rocks. The study has brought together three linked, but distinct, elements; a mathematical analysis of the intersection of ellipses, a review of field measurements associated with nuclear waste repository investigations and probabilistic simulations using a lattice network numerical model. We conclude that the model of channels that traverse fracture intersections without necessarily branching is a very likely representation of reality. More generally, assembling all the lines of evidence, it is suggested that groundwater flow systems in fractured crystalline rocks in the environs of underground laboratories have the following characteristics: Groundwater flows within a sparse network of channels just above the percolation limit. The frequency of intersections is low in that individual channels extend considerable distances between significant junctions. Individual channels often extend over many fracture surfaces and the resulting flow system is only weakly related to the density or size of mappable fractures. The sparseness of systems compared to the size of drifts and tunnels means that only a very few flow channels are intersected by drifts and tunnels. Highly convergent flow is required to connect to the rest of the network and this is misinterpreted as a skin of low hydraulic conductivity. Systems are so sparse that they are controlled by a few 'chokes' that give rise to compartments of head, and probably, of groundwater chemistry. Channels occur on all fracture planes, including those within fracture zones, and although the characteristics of the fracture zone channel networks may differ from those in surrounding rocks, they are nonetheless still channel networks. The actively flowing sparse channel network, occurring within any particular rock, is a naturally selected, small sub-set of the available channels. Hence, there are many

A Performance Evaluation Model for Mobile Ad Hoc Networks and Sensor Networks

Directory of Open Access Journals (Sweden)

Heng LUO

2014-03-01

Full Text Available Potential applications in areas such as military sites and disaster relief fields that are characterized by absence of prefixed infrastructure justify the development of mobile ad hoc networks (MANETs and wireless sensor networks (WSNs. However, unfavorable wireless links and dynamic topology are still challenging, leading to the proposal of a collection of routing protocols for MANETs and WSNs. Nevertheless the performance of algorithms may vary with deployment scenario due to the application dependent philosophy behind algorithms. In this paper, the performance evaluation problem for MANETs and WSNs is investigated and a novel performance ranking model, termed AHP-SAW, is proposed. For simplicity but without loss of generality, the performance of two routing protocols DSDV and DSR are studies based on which ranking results are provided. Extensive simulations show that an overall 37.2 %, at most, gain may be achieved based on the AHP-SAW model.

Topological Effects and Performance Optimization in Transportation Continuous Network Design

Directory of Open Access Journals (Sweden)

Jianjun Wu

2014-01-01

Full Text Available Because of the limitation of budget, in the planning of road works, increased efforts should be made on links that are more critical to the whole traffic system. Therefore, it would be helpful to model and evaluate the vulnerability and reliability of the transportation network when the network design is processing. This paper proposes a bilevel transportation network design model, in which the upper level is to minimize the performance of the network under the given budgets, while the lower level is a typical user equilibrium assignment problem. A new solution approach based on particle swarm optimization (PSO method is presented. The topological effects on the performance of transportation networks are studied with the consideration of three typical networks, regular lattice, random graph, and small-world network. Numerical examples and simulations are presented to demonstrate the proposed model.

Performance evaluation of packet video transfer over local area networks

OpenAIRE

Lu, Jie

1993-01-01

This research investigates the implementation and performance of packet video transfer over local area networks. A network architecture is defined for packet video such that most of the processing is performed by the higher layers of the Open Systems Interconnection (OSI) reference model, while the lower layers provide real-time services. Implementation methods are discussed for coding schemes, including data compression, the network interface unit, and the underlying local are...

Network Degradation Effects on Different Codec Types and Characteristics of Video Streaming

Directory of Open Access Journals (Sweden)

Jaroslav Frnda

2014-01-01

Full Text Available Nowadays, there is a quickly growing demand for the transmission of voice, video and data over an IP based network. Multimedia, whether we are talking about broadcast, audio and video transmission and others, from a global perspective is growing exponentially with time. With incoming requests from users, new technologies for data transfer are continually developing. Data must be delivered reliably and with the fewest losses at such high speed. Video quality as part of multimedia technology has a very important role nowadays. It is influenced by several factors, where each of them can have many forms and processing. Network performance is the major degradation effect that influences the quality of resulting image. Poor network performance (lack of link capacity, high network load… causes data packet losses or different delivery time for each packet. This work focuses exactly on these network phenomena. It examines the impact of different delays and packet losses on the quality parameters of triple play services, to evaluate the results using objective methods. The aim of this work is to bring a detailed view on the performance of video streaming over IP-based networks.

A Mathematical Model to Improve the Performance of Logistics Network

Directory of Open Access Journals (Sweden)

Muhammad Izman Herdiansyah

2012-01-01

Full Text Available The role of logistics nowadays is expanding from just providing transportation and warehousing to offering total integrated logistics. To remain competitive in the global market environment, business enterprises need to improve their logistics operations performance. The improvement will be achieved when we can provide a comprehensive analysis and optimize its network performances. In this paper, a mixed integer linier model for optimizing logistics network performance is developed. It provides a single-product multi-period multi-facilities model, as well as the multi-product concept. The problem is modeled in form of a network flow problem with the main objective to minimize total logistics cost. The problem can be solved using commercial linear programming package like CPLEX or LINDO. Even in small case, the solver in Excel may also be used to solve such model.Keywords: logistics network, integrated model, mathematical programming, network optimization

Evaluation of Techniques to Detect Significant Network Performance Problems using End-to-End Active Network Measurements

Energy Technology Data Exchange (ETDEWEB)

Cottrell, R.Les; Logg, Connie; Chhaparia, Mahesh; /SLAC; Grigoriev, Maxim; /Fermilab; Haro, Felipe; /Chile U., Catolica; Nazir, Fawad; /NUST, Rawalpindi; Sandford, Mark

2006-01-25

End-to-End fault and performance problems detection in wide area production networks is becoming increasingly hard as the complexity of the paths, the diversity of the performance, and dependency on the network increase. Several monitoring infrastructures are built to monitor different network metrics and collect monitoring information from thousands of hosts around the globe. Typically there are hundreds to thousands of time-series plots of network metrics which need to be looked at to identify network performance problems or anomalous variations in the traffic. Furthermore, most commercial products rely on a comparison with user configured static thresholds and often require access to SNMP-MIB information, to which a typical end-user does not usually have access. In our paper we propose new techniques to detect network performance problems proactively in close to realtime and we do not rely on static thresholds and SNMP-MIB information. We describe and compare the use of several different algorithms that we have implemented to detect persistent network problems using anomalous variations analysis in real end-to-end Internet performance measurements. We also provide methods and/or guidance for how to set the user settable parameters. The measurements are based on active probes running on 40 production network paths with bottlenecks varying from 0.5Mbits/s to 1000Mbit/s. For well behaved data (no missed measurements and no very large outliers) with small seasonal changes most algorithms identify similar events. We compare the algorithms' robustness with respect to false positives and missed events especially when there are large seasonal effects in the data. Our proposed techniques cover a wide variety of network paths and traffic patterns. We also discuss the applicability of the algorithms in terms of their intuitiveness, their speed of execution as implemented, and areas of applicability. Our encouraging results compare and evaluate the accuracy of our

Use of communication architecture test bed to evaluate data network performance

International Nuclear Information System (INIS)

Clapp, N.E. Jr.; Swail, B.K.; Naser, J.A.

1994-01-01

Local area networks (LANs) are becoming more prevalent in nuclear power plants. Traditionally, LANs were only used as information highways, providing office automation services. LANs are now being used as data highways for applications in plant data acquisition and control systems. A communication architecture test bed, which contains network simulators, is needed to allow network performance studies and to resolve design issues prior to equipment purchase. Two levels of granularity of simulation are needed to provide the dynamic information about network performance. A coarse-grain simulator is used to estimate the dynamic performance of the network due to major resources such as workstations, gateways, and data acquisition systems. A fine-grain simulator allows a greater level of detail about the underlying network protocol and resources to be simulated. The combination of coarse-grain and fine-grain simulation packages provides the network designer with the required tools to thoroughly understand the behavior of the modeled network. This paper describes the development of a communication architecture test bed using commercial network simulation packages. Network simulators allow the resolution of major design issues in software without the expense of purchasing costly hardware components

Optimisation of Software-Defined Networks Performance Using a Hybrid Intelligent System

Directory of Open Access Journals (Sweden)

Ann Sabih

2017-06-01

Full Text Available This paper proposes a novel intelligent technique that has been designed to optimise the performance of Software Defined Networks (SDN. The proposed hybrid intelligent system has employed integration of intelligence-based optimisation approaches with the artificial neural network. These heuristic optimisation methods include Genetic Algorithms (GA and Particle Swarm Optimisation (PSO. These methods were utilised separately in order to select the best inputs to maximise SDN performance. In order to identify SDN behaviour, the neural network model is trained and applied. The maximal optimisation approach has been identified using an analytical approach that considered SDN performance and the computational time as objective functions. Initially, the general model of the neural network was tested with unseen data before implementing the model using GA and PSO to determine the optimal performance of SDN. The results showed that the SDN represented by Artificial Neural Network ANN, and optmised by PSO, generated a better configuration with regards to computational efficiency and performance index.

Performance Analysis of On-Demand Routing Protocols in Wireless Mesh Networks

Directory of Open Access Journals (Sweden)

Arafatur RAHMAN

2009-01-01

Full Text Available Wireless Mesh Networks (WMNs have recently gained a lot of popularity due to their rapid deployment and instant communication capabilities. WMNs are dynamically self-organizing, self-configuring and self-healing with the nodes in the network automatically establishing an adiej hoc network and preserving the mesh connectivity. Designing a routing protocol for WMNs requires several aspects to consider, such as wireless networks, fixed applications, mobile applications, scalability, better performance metrics, efficient routing within infrastructure, load balancing, throughput enhancement, interference, robustness etc. To support communication, various routing protocols are designed for various networks (e.g. ad hoc, sensor, wired etc.. However, all these protocols are not suitable for WMNs, because of the architectural differences among the networks. In this paper, a detailed simulation based performance study and analysis is performed on the reactive routing protocols to verify the suitability of these protocols over such kind of networks. Ad Hoc On-Demand Distance Vector (AODV, Dynamic Source Routing (DSR and Dynamic MANET On-demand (DYMO routing protocol are considered as the representative of reactive routing protocols. The performance differentials are investigated using varying traffic load and number of source. Based on the simulation results, how the performance of each protocol can be improved is also recommended.

Network topology analysis.

Energy Technology Data Exchange (ETDEWEB)

Kalb, Jeffrey L.; Lee, David S.

2008-01-01

Emerging high-bandwidth, low-latency network technology has made network-based architectures both feasible and potentially desirable for use in satellite payload architectures. The selection of network topology is a critical component when developing these multi-node or multi-point architectures. This study examines network topologies and their effect on overall network performance. Numerous topologies were reviewed against a number of performance, reliability, and cost metrics. This document identifies a handful of good network topologies for satellite applications and the metrics used to justify them as such. Since often multiple topologies will meet the requirements of the satellite payload architecture under development, the choice of network topology is not easy, and in the end the choice of topology is influenced by both the design characteristics and requirements of the overall system and the experience of the developer.

Social network characteristics and cervical cancer screening among Quechua women in Andean Peru.

Science.gov (United States)

Luque, John S; Opoku, Samuel; Ferris, Daron G; Guevara Condorhuaman, Wendy S

2016-02-24

Peru has high cervical cancer incidence and mortality rates compared to other Andean countries. Therefore, partnerships between governmental and international organizations have targeted rural areas of Peru to receive cervical cancer screening via outreach campaigns. Previous studies have found a relationship between a person's social networks and cancer screening behaviors. Screening outreach campaigns conducted by the nonprofit organization CerviCusco created an opportunity for a social network study to examine cervical cancer screening history and social network characteristics in a rural indigenous community that participated in these campaigns in 2012 and 2013. The aim of this study was to explore social network characteristics in this community related to receipt of cervical cancer screening following the campaigns. An egocentric social network questionnaire was used to collect cross-sectional network data on community participants. Each survey participant (ego) was asked to name six other women they knew (alters) and identify the nature of their relationship or tie (family, friend, neighbor, other), residential closeness (within 5 km), length of time known, frequency of communication, topics of conversation, and whether they lent money to the person, provided childcare or helped with transportation. In addition, each participant was asked to report the nature of the relationship between all alters identified (e.g., friend, family, or neighbor). Bivariate and multivariate analyses were used to explore the relationship between Pap test receipt at the CerviCusco outreach screening campaigns and social network characteristics. Bivariate results found significant differences in percentage of alter composition for neighbors and family, and for mean number of years known, mean density, and mean degree centrality between women who had received a Pap test (n = 19) compared to those who had not (n = 50) (p's < 0.05). The final logistic regression model was

Friendship Network Characteristics Are Associated with Physical Activity and Sedentary Behavior in Early Adolescence.

Science.gov (United States)

Marks, Jennifer; de la Haye, Kayla; Barnett, Lisa M; Allender, Steven

2015-01-01

There is limited understanding of the association between peer social networks and physical activity (PA), sedentary and screen-related behaviors. This study reports on associations between personal network characteristics and these important health behaviors for early adolescents. Participants were 310 students, aged 11-13 years, from fifteen randomly selected Victorian primary schools (43% response rate). PA and sedentary behaviors were collected via accelerometer and self-report questionnaire, and anthropometric measures via trained researchers. Participants nominated up to fifteen friends, and described the frequency of interaction and perceived activity intensity of these friends. Personal network predictors were examined using regression modelling for PA and sedentary/screen behavior. Perceived activity levels of friends, and friendships with very frequent interaction were associated with outside-of-school PA and/or sedentary/screen time. Differences according to sex were also observed in the association between network characteristics and PA and sedentary time. A higher number of friends and greater proportion of same sex friends were associated with boys engaging in more moderate-to-vigorous PA outside of school hours. PA intensity during school-day breaks was positively associated with having a greater proportion of friends who played sports for girls, and a greater proportion of male friends for boys. Friendship network characteristics are associated with PA and sedentary/screen time in late childhood/early adolescence, and these associations differ by sex. The positive influence of very active peers may be a promising avenue to strengthen traditional interventions for the promotion of PA and reduction in screen time.

Social Network Characteristics, Social Support, and Cigarette Smoking among Asian/Pacific Islander Young Adults.

Science.gov (United States)

Pokhrel, Pallav; Fagan, Pebbles; Cassel, Kevin; Trinidad, Dennis R; Kaholokula, Joseph Keawe'aimoku; Herzog, Thaddeus A

2016-06-01

Cigarette smoking may be one of the factors contributing to the high levels of cancer-related mortality experienced by certain Asian/Pacific Islander (A/PI) subgroups (e.g., Native Hawaiian). Given the collectivist cultural orientation attributed to A/PI groups, social strategies are recommended for substance abuse or smoking cessation treatment among A/PI. However, research examining how social network characteristics and social support relate to smoking across A/PI subgroups has been lacking. This study investigated the associations between social network characteristics (e.g., size, composition), perceived social support, and recent cigarette use across Native Hawaiian, Filipino, and East Asian (e.g., Japanese, Chinese) young adults (18-35 year old). Cross-sectional, self-report data were collected from N = 435 participants (M age = 25.6, SD = 8.3; 61% women). Ethnic differences were found in a number of pathways linking social network characteristics, perceived social support, and cigarette smoking. Larger network size was strongly associated with higher perceived social support and lower recent cigarette smoking among Native Hawaiians but not Filipinos or East Asians. Higher perceived social support was associated with lower recent smoking among East Asians and Filipinos but not Native Hawaiians. Implications are discussed with regard to smoking prevention and cessation among A/PI. © Society for Community Research and Action 2016.

Research about reactor operator's personality characteristics and performance

International Nuclear Information System (INIS)

Wei Li; He Xuhong; Zhao Bingquan

2003-01-01

To predict and evaluate the reactor operator's performance by personality characteristics is an important part of reactor operator safety assessment. Using related psychological theory combined with the Chinese operator's fact and considering the effect of environmental factors to personality analysis, paper does the research about the about the relationships between reactor operator's performance and personality characteristics, and offers the reference for operator's selection, using and performance in the future. (author)

Evaluation of high-performance network technologies for ITER

International Nuclear Information System (INIS)

Zagar, K.; Hunt, S.; Kolaric, P.; Sabjan, R.; Zagar, A.; Dedic, J.

2010-01-01

For the fast feedback plasma controllers, ITER's Control, Data Access and Communication system (CODAC) will need to provide a mechanism for hard real-time communication between its distributed nodes. In particular, the ITER CODAC team identified four types of high-performance communication applications. Synchronous Databus Network (SDN) is to provide an ability to distribute parameters of plasma (estimated to about 5000 double-valued signals) across the system to allow for 1 ms control cycles. Event Distribution Network (EDN) and Time Communication Network (TCN) are to allow synchronization of node I/O operations to 10 ns. Finally, the Audio-Video Network (AVN) is to provide sufficient bandwidth for streaming of surveillance and diagnostics video at a high resolution (1024 x 1024) and frame rate (30 Hz). In this article, we present some combinations of common-off-the-shelf (COTS) technologies that allow the above requirements to be met. Also, we present the performances achieved in a practical (though small scale) technology demonstrator, which involved a real-time Linux operating running on National Instruments' PXI platform, UDP communication implemented directly atop the Ethernet network adapter, CISCO switches, Micro Research Finland's timing and event solution, and GigE audio-video streaming.

An Analysis of Network and Sensor Performance Within IEEE 802.X Wireless MESH Networks in the Tactical Network Topology (TNT)

National Research Council Canada - National Science Library

Davis, Joseph A., Sr

2005-01-01

.... Specifically, this thesis will attempt establish the foundation for the development of wireless MESH "network health" models by examining the performance of sensors operating within a MESH network...

A Step towards Developing a Sustainability Performance Measure within Industrial Networks

Directory of Open Access Journals (Sweden)

Samaneh Shokravi

2014-04-01

Full Text Available Despite the plethora of literature in sustainability and supply chain management in the recent years, a quantitative tool that measures the sustainability performance of an industrial supply network, considering the uncertainties of existing data, is hard to find. This conceptual paper is aimed at establishing a quantitative measure for the sustainability performance of industrial supply networks that considers aleatory and epistemic uncertainties in its environmental performance evaluation. The measure is built upon economic, environmental and social performance evaluation models. These models address a number of shortcomings in the literature, such as incomplete and inaccurate calculation of environmental impacts, as well as the disregard for aleatory and epistemic uncertainties in the input data and, more importantly, the scarce number of quantitative social sustainability measures. Dyadic interactions are chosen for the network, while the network members have a revenue-sharing relationship. This relationship promotes sharing of the required information for the use of the proposed model. This measure provides an approach to quantify the environmental, social and economic sustainability performances of a supply network. Moreover, as this measure is not specifically designed for an industrial sector, it can be employed over an evolving and diverse industrial network.

High Performance Networks From Supercomputing to Cloud Computing

CERN Document Server

Abts, Dennis

2011-01-01

Datacenter networks provide the communication substrate for large parallel computer systems that form the ecosystem for high performance computing (HPC) systems and modern Internet applications. The design of new datacenter networks is motivated by an array of applications ranging from communication intensive climatology, complex material simulations and molecular dynamics to such Internet applications as Web search, language translation, collaborative Internet applications, streaming video and voice-over-IP. For both Supercomputing and Cloud Computing the network enables distributed applicati

Hydraulic and separation characteristics of an industrial gas centrifuge calculated with neural networks

Science.gov (United States)

Butov, Vladimir; Timchenko, Sergey; Ushakov, Ivan; Golovkov, Nikita; Poberezhnikov, Andrey

2018-03-01

Single gas centrifuge (GC) is generally used for the separation of binary mixtures of isotopes. Processes taking place within the centrifuge are complex and non-linear. Their characteristics can change over time with long-term operation due to wear of the main structural elements of the GC construction. The paper is devoted to the determination of basic operation parameters of the centrifuge with the help of neural networks. We have developed a method for determining the parameters of the industrial GC operation by processing statistical data. In this work, we have constructed a neural network that is capable of determining the main hydraulic and separation characteristics of the gas centrifuge, depending on the geometric dimensions of the gas centrifuge, load value, and rotor speed.

Topology design and performance analysis of an integrated communication network

Science.gov (United States)

Li, V. O. K.; Lam, Y. F.; Hou, T. C.; Yuen, J. H.

1985-01-01

A research study on the topology design and performance analysis for the Space Station Information System (SSIS) network is conducted. It is begun with a survey of existing research efforts in network topology design. Then a new approach for topology design is presented. It uses an efficient algorithm to generate candidate network designs (consisting of subsets of the set of all network components) in increasing order of their total costs, and checks each design to see if it forms an acceptable network. This technique gives the true cost-optimal network, and is particularly useful when the network has many constraints and not too many components. The algorithm for generating subsets is described in detail, and various aspects of the overall design procedure are discussed. Two more efficient versions of this algorithm (applicable in specific situations) are also given. Next, two important aspects of network performance analysis: network reliability and message delays are discussed. A new model is introduced to study the reliability of a network with dependent failures. For message delays, a collection of formulas from existing research results is given to compute or estimate the delays of messages in a communication network without making the independence assumption. The design algorithm coded in PASCAL is included as an appendix.

Unmanned Aerial ad Hoc Networks: Simulation-Based Evaluation of Entity Mobility Models’ Impact on Routing Performance

Directory of Open Access Journals (Sweden)

Jean-Daniel Medjo Me Biomo

2015-06-01

Full Text Available An unmanned aerial ad hoc network (UAANET is a special type of mobile ad hoc network (MANET. For these networks, researchers rely mostly on simulations to evaluate their proposed networking protocols. Hence, it is of great importance that the simulation environment of a UAANET replicates as much as possible the reality of UAVs. One major component of that environment is the movement pattern of the UAVs. This means that the mobility model used in simulations has to be thoroughly understood in terms of its impact on the performance of the network. In this paper, we investigate how mobility models affect the performance of UAANET in simulations in order to come up with conclusions/recommendations that provide a benchmark for future UAANET simulations. To that end, we first propose a few metrics to evaluate the mobility models. Then, we present five random entity mobility models that allow nodes to move almost freely and independently from one another and evaluate four carefully-chosen MANET/UAANET routing protocols: ad hoc on-demand distance vector (AODV, optimized link state routing (OLSR, reactive-geographic hybrid routing (RGR and geographic routing protocol (GRP. In addition, flooding is also evaluated. The results show a wide variation of the protocol performance over different mobility models. These performance differences can be explained by the mobility model characteristics, and we discuss these effects. The results of our analysis show that: (i the enhanced Gauss–Markov (EGM mobility model is best suited for UAANET; (ii OLSR, a table-driven proactive routing protocol, and GRP, a position-based geographic protocol, are the protocols most sensitive to the change of mobility models; (iii RGR, a reactive-geographic hybrid routing protocol, is best suited for UAANET.

Performance verification of network function virtualization in software defined optical transport networks

Science.gov (United States)

Zhao, Yongli; Hu, Liyazhou; Wang, Wei; Li, Yajie; Zhang, Jie

2017-01-01

With the continuous opening of resource acquisition and application, there are a large variety of network hardware appliances deployed as the communication infrastructure. To lunch a new network application always implies to replace the obsolete devices and needs the related space and power to accommodate it, which will increase the energy and capital investment. Network function virtualization1 (NFV) aims to address these problems by consolidating many network equipment onto industry standard elements such as servers, switches and storage. Many types of IT resources have been deployed to run Virtual Network Functions (vNFs), such as virtual switches and routers. Then how to deploy NFV in optical transport networks is a of great importance problem. This paper focuses on this problem, and gives an implementation architecture of NFV-enabled optical transport networks based on Software Defined Optical Networking (SDON) with the procedure of vNFs call and return. Especially, an implementation solution of NFV-enabled optical transport node is designed, and a parallel processing method for NFV-enabled OTN nodes is proposed. To verify the performance of NFV-enabled SDON, the protocol interaction procedures of control function virtualization and node function virtualization are demonstrated on SDON testbed. Finally, the benefits and challenges of the parallel processing method for NFV-enabled OTN nodes are simulated and analyzed.

Planning Multitechnology Access Networks with Performance Constraints

Science.gov (United States)

Chamberland, Steven

Considering the number of access network technologies and the investment needed for the “last mile” of a solution, in today’s highly competitive markets, planning tools are crucial for the service providers to optimize the network costs and accelerate the planning process. In this paper, we propose to tackle the problem of planning access networks composed of four technologies/architectures: the digital subscriber line (xDSL) technologies deployed directly from the central office (CO), the fiber-to-the-node (FTTN), the fiber-to-the-micro-node (FTTn) and the fiber-to-the-premises (FTTP). A mathematical programming model is proposed for this planning problem that is solved using a commercial implementation of the branch-and-bound algorithm. Next, a detailed access network planning example is presented followed by a systematic set of experiments designed to assess the performance of the proposed approach.

Analiza karakteristika MPLS simulatora / Characteristics analyse of the MPLS network simulator

Directory of Open Access Journals (Sweden)

Boban Pavlović

2005-05-01

Full Text Available U ovom radu predstavljena je arhitektura i analizirane su karakteristike MPLS mrežnog simulatora MNS (Multiprotocol Label Switching Network Simulator, koji se koristi u projektovanju paketskih mreža zasnovanih na IP (Internet Protocol protokolu koje moraju podržavati saobraćaj u realnom vremenu i multimedijalni saobraćaj. Na bazi mrežnog simulatora prikazane su i opisane procedure simulacije saobraćaja različitog QoS, kao i simulacija posluživanja saobraćaja višeg prioriteta. / In this article are presented architecture and characteristics analyze of the MPLS Network Simulator (MNS. MNS is used for design packet networks based on Internet Protocol (IP which must support Real-time Traffic and Multimedia. In this document are presented and described simulation procedure for traffics -with different QoS and simulation for resource preemption.

EO-Performance relationships in Reverse Internationalization by Chinese Global Startup OEMs: Social Networks and Strategic Flexibility

Science.gov (United States)

Chin, Tachia; Tsai, Sang-Bing; Fang, Kai; Zhu, Wenzhong; Yang, Dongjin; Liu, Ren-huai; Tsuei, Richard Ting Chang

2016-01-01

Due to the context-sensitive nature of entrepreneurial orientation (EO), it is imperative to in-depth explore the EO-performance mechanism in China at its critical, specific stage of economic reform. Under the context of “reverse internationalization” by Chinese global startup original equipment manufacturers (OEMs), this paper aims to manifest the unique links and complicated interrelationships between the individual EO dimensions and firm performance. Using structural equation modeling, we found that during reverse internationalization, proactiveness is positively related to performance; risk taking is not statistically associated with performance; innovativeness is negatively related to performance. The proactiveness-performance relationship is mediated by Strategic flexibility and moderated by social networking relationships. The dynamic and complex institutional setting, coupled with the issues of overcapacity and rising labor cost in China may explain why our distinctive results occur. This research advances the understanding of how contingent factors (social network relationships and strategic flexibility) facilitate entrepreneurial firms to break down institutional barriers and reap the most from EO. It brings new insights into how Chinese global startup OEMs draw on EO to undertake reverse internationalization, responding the calls for unraveling the heterogeneous characteristics of EO sub-dimensions and for more contextually-embedded treatment of EO-performance associations. PMID:27631368

EO-Performance relationships in Reverse Internationalization by Chinese Global Startup OEMs: Social Networks and Strategic Flexibility.

Science.gov (United States)

Chin, Tachia; Tsai, Sang-Bing; Fang, Kai; Zhu, Wenzhong; Yang, Dongjin; Liu, Ren-Huai; Tsuei, Richard Ting Chang

2016-01-01

Due to the context-sensitive nature of entrepreneurial orientation (EO), it is imperative to in-depth explore the EO-performance mechanism in China at its critical, specific stage of economic reform. Under the context of "reverse internationalization" by Chinese global startup original equipment manufacturers (OEMs), this paper aims to manifest the unique links and complicated interrelationships between the individual EO dimensions and firm performance. Using structural equation modeling, we found that during reverse internationalization, proactiveness is positively related to performance; risk taking is not statistically associated with performance; innovativeness is negatively related to performance. The proactiveness-performance relationship is mediated by Strategic flexibility and moderated by social networking relationships. The dynamic and complex institutional setting, coupled with the issues of overcapacity and rising labor cost in China may explain why our distinctive results occur. This research advances the understanding of how contingent factors (social network relationships and strategic flexibility) facilitate entrepreneurial firms to break down institutional barriers and reap the most from EO. It brings new insights into how Chinese global startup OEMs draw on EO to undertake reverse internationalization, responding the calls for unraveling the heterogeneous characteristics of EO sub-dimensions and for more contextually-embedded treatment of EO-performance associations.

Depression, Smoking, and Ego-Centric Social Network Characteristics in Ohio Appalachian Women.

Science.gov (United States)

Lam, Jeffrey; Lu, Bo; Doogan, Nate; Thomson, Tiffany; Ferketich, Amy; Paskett, Electra D; Wewers, Mary Ellen

2017-01-01

Depression is a serious, costly, and debilitating disorder that is understudied in rural women. Studies show that depression is associated with low social integration and support, but few studies investigate the relationship between depression and social network characteristics. This study examined the associations among women from three Ohio Appalachian counties enrolled in a health study, which aimed to collect information for a future social network smoking cessation intervention. An address-based sampling method was used to randomly select and recruit 404 women. A cross-sectional survey and interview were used to collect information about demographic, psychosocial, behavioral factors, and ego-centric social network characteristics, which are variables derived from an individual (ego) and her first degree contacts (alters). The CES-D scale assessed depressive symptoms. A multivariable logistic regression analysis described the association between these factors and participants with depression (defined as CES-D≥16). Higher network density, or greater number of relationships among alters divided by the total amount of alters, reduced the risk for depression (OR = 0.84, 95% confidence interval [CI] 0.73-0.95). Additionally, women with a high percentage of smoking alters were at greater risk for depression (OR = 1.19, 95% CI 1.02-1.39). Other factors associated with risk for depression included perceived stress score (OR = 1.34, 95% CI 1.24-1.45), loneliness score (OR = 1.37, 95% CI 1.05-1.80), and days with poor physical health (OR = 1.06, 95% CI 1.02-1.11). Findings suggest that psychosocial factors and social networks should be considered when addressing depression in clinical practice.

Generating Billion-Edge Scale-Free Networks in Seconds: Performance Study of a Novel GPU-based Preferential Attachment Model

Energy Technology Data Exchange (ETDEWEB)

Perumalla, Kalyan S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Alam, Maksudul [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-10-01

A novel parallel algorithm is presented for generating random scale-free networks using the preferential-attachment model. The algorithm, named cuPPA, is custom-designed for single instruction multiple data (SIMD) style of parallel processing supported by modern processors such as graphical processing units (GPUs). To the best of our knowledge, our algorithm is the first to exploit GPUs, and also the fastest implementation available today, to generate scale free networks using the preferential attachment model. A detailed performance study is presented to understand the scalability and runtime characteristics of the cuPPA algorithm. In one of the best cases, when executed on an NVidia GeForce 1080 GPU, cuPPA generates a scale free network of a billion edges in less than 2 seconds.

Evaluation of High-Performance Network Technologies for ITER

Energy Technology Data Exchange (ETDEWEB)

Zagar, K.; Kolaric, P.; Sabjan, R.; Zagar, A. [Cosylab d.d., Ljubljana (Slovenia); Hunt, S. [Alceli Hunt Beratung, Meisterschwanden (Switzerland)

2009-07-01

To facilitate fast feedback control of plasma, ITER's Control, Data Access and Communication system (CODAC) will need to provide a mechanism for hard real-time communication between its distributed nodes. In particular, four types of high-performance communication have been identified. Synchronous Databus Network (SDN) is to provide an ability to distribute parameters of plasma (estimated to about 5000 double-valued signals) across the system to allow for 1 ms control cycles. Event Distribution Network (EDN) and Time Communication Network (TCN) are to allow synchronization of node I/O operations to 10 ns. Finally, the Audio Video Network (AVN) is to provide sufficient bandwidth for streaming of surveillance and diagnostics video at a high resolution (1024*1024) and frame rate (30 Hz). In this article, we present some combinations of common off-the-shelf (COTS) technologies that allow the above requirements to be met. Also, we present the performances achieved in a practical (though small scale) technology demonstrator, which involved a real-time LINUS operating running on National Instruments' PXI platform, UDP communication implemented directly atop the Ethernet network adapter, CISCO switches, Micro Research Finland's timing and event solution, and GigE audio-video streaming. This document is composed of an abstract followed by the presentation transparencies. (authors)

Evaluation of high-performance network technologies for ITER

Energy Technology Data Exchange (ETDEWEB)

Zagar, K., E-mail: klemen.zagar@cosylab.co [Cosylab d.d., 1000 Ljubljana (Slovenia); Hunt, S. [Alceli Hunt Beratung, 5616 Meisterschwanden (Switzerland); Kolaric, P.; Sabjan, R.; Zagar, A.; Dedic, J. [Cosylab d.d., 1000 Ljubljana (Slovenia)

2010-07-15

For the fast feedback plasma controllers, ITER's Control, Data Access and Communication system (CODAC) will need to provide a mechanism for hard real-time communication between its distributed nodes. In particular, the ITER CODAC team identified four types of high-performance communication applications. Synchronous Databus Network (SDN) is to provide an ability to distribute parameters of plasma (estimated to about 5000 double-valued signals) across the system to allow for 1 ms control cycles. Event Distribution Network (EDN) and Time Communication Network (TCN) are to allow synchronization of node I/O operations to 10 ns. Finally, the Audio-Video Network (AVN) is to provide sufficient bandwidth for streaming of surveillance and diagnostics video at a high resolution (1024 x 1024) and frame rate (30 Hz). In this article, we present some combinations of common-off-the-shelf (COTS) technologies that allow the above requirements to be met. Also, we present the performances achieved in a practical (though small scale) technology demonstrator, which involved a real-time Linux operating running on National Instruments' PXI platform, UDP communication implemented directly atop the Ethernet network adapter, CISCO switches, Micro Research Finland's timing and event solution, and GigE audio-video streaming.

The social support and social network characteristics of smokers in methadone maintenance treatment.

Science.gov (United States)

de Dios, Marcel Alejandro; Stanton, Cassandra A; Caviness, Celeste M; Niaura, Raymond; Stein, Michael

2013-01-01

Previous studies have shown social support and social network variables to be important factors in smoking cessation treatment. Tobacco use is highly prevalent among individuals in methadone maintenance treatment (MMT). However, smoking cessation treatment outcomes in this vulnerable subpopulation have been poor and social support and social network variables may contribute. The current study examined the social support and social network characteristics of 151 MMT smokers involved in a randomized clinical trial of smoking cessation treatments. Participants were 50% women and 78% Caucasian. A high proportion (57%) of MMT smokers had spouses or partners who smoke and over two-thirds of households (68.5%) included at least one smoker. Our sample was characterized by relatively small social networks, but high levels of general social support and quitting support. The number of cigarettes per day was found to be positively associated with the number of smokers in the social network (r = .239, p social support and social networks of smokers in MMT.

Research on robust optimization of emergency logistics network considering the time dependence characteristic

Science.gov (United States)

WANG, Qingrong; ZHU, Changfeng; LI, Ying; ZHANG, Zhengkun

2017-06-01

Considering the time dependence of emergency logistic network and complexity of the environment that the network exists in, in this paper the time dependent network optimization theory and robust discrete optimization theory are combined, and the emergency logistics dynamic network optimization model with characteristics of robustness is built to maximize the timeliness of emergency logistics. On this basis, considering the complexity of dynamic network and the time dependence of edge weight, an improved ant colony algorithm is proposed to realize the coupling of the optimization algorithm and the network time dependence and robustness. Finally, a case study has been carried out in order to testify validity of this robustness optimization model and its algorithm, and the value of different regulation factors was analyzed considering the importance of the value of the control factor in solving the optimal path. Analysis results show that this model and its algorithm above-mentioned have good timeliness and strong robustness.

Social network characteristics and cervical cancer screening among Quechua women in Andean Peru

Directory of Open Access Journals (Sweden)

John S. Luque

2016-02-01

Full Text Available Abstract Background Peru has high cervical cancer incidence and mortality rates compared to other Andean countries. Therefore, partnerships between governmental and international organizations have targeted rural areas of Peru to receive cervical cancer screening via outreach campaigns. Previous studies have found a relationship between a person’s social networks and cancer screening behaviors. Screening outreach campaigns conducted by the nonprofit organization CerviCusco created an opportunity for a social network study to examine cervical cancer screening history and social network characteristics in a rural indigenous community that participated in these campaigns in 2012 and 2013. The aim of this study was to explore social network characteristics in this community related to receipt of cervical cancer screening following the campaigns. Methods An egocentric social network questionnaire was used to collect cross-sectional network data on community participants. Each survey participant (ego was asked to name six other women they knew (alters and identify the nature of their relationship or tie (family, friend, neighbor, other, residential closeness (within 5 km, length of time known, frequency of communication, topics of conversation, and whether they lent money to the person, provided childcare or helped with transportation. In addition, each participant was asked to report the nature of the relationship between all alters identified (e.g., friend, family, or neighbor. Bivariate and multivariate analyses were used to explore the relationship between Pap test receipt at the CerviCusco outreach screening campaigns and social network characteristics. Results Bivariate results found significant differences in percentage of alter composition for neighbors and family, and for mean number of years known, mean density, and mean degree centrality between women who had received a Pap test (n = 19 compared to those who had not (n = 50 (p�

Testing the Feasibility of a Low-Cost Network Performance Measurement Infrastructure

Energy Technology Data Exchange (ETDEWEB)

Chevalier, Scott [Indiana Univ., Bloomington, IN (United States). International Networks; Schopf, Jennifer M. [Indiana Univ., Bloomington, IN (United States). International Networks; Miller, Kenneth [Pennsylvania State Univ., University Park, PA (United States). Telecommunications and Networking Services; Zurawski, Jason [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Energy Sciences Network

2016-07-01

Todays science collaborations depend on reliable, high performance networks, but monitoring the end-to-end performance of a network can be costly and difficult. The most accurate approaches involve using measurement equipment in many locations, which can be both expensive and difficult to manage due to immobile or complicated assets. The perfSONAR framework facilitates network measurement making management of the tests more reasonable. Traditional deployments have used over-provisioned servers, which can be expensive to deploy and maintain. As scientific network uses proliferate, there is a desire to instrument more facets of a network to better understand trends. This work explores low cost alternatives to assist with network measurement. Benefits include the ability to deploy more resources quickly, and reduced capital and operating expenditures. Finally, we present candidate platforms and a testing scenario that evaluated the relative merits of four types of small form factor equipment to deliver accurate performance measurements.

The effects of local street network characteristics on the positional accuracy of automated geocoding for geographic health studies

Directory of Open Access Journals (Sweden)

Zimmerman Dale L

2010-02-01

Full Text Available Abstract Background Automated geocoding of patient addresses for the purpose of conducting spatial epidemiologic studies results in positional errors. It is well documented that errors tend to be larger in rural areas than in cities, but possible effects of local characteristics of the street network, such as street intersection density and street length, on errors have not yet been documented. Our study quantifies effects of these local street network characteristics on the means and the entire probability distributions of positional errors, using regression methods and tolerance intervals/regions, for more than 6000 geocoded patient addresses from an Iowa county. Results Positional errors were determined for 6376 addresses in Carroll County, Iowa, as the vector difference between each 100%-matched automated geocode and its ground-truthed location. Mean positional error magnitude was inversely related to proximate street intersection density. This effect was statistically significant for both rural and municipal addresses, but more so for the former. Also, the effect of street segment length on geocoding accuracy was statistically significant for municipal, but not rural, addresses; for municipal addresses mean error magnitude increased with length. Conclusion Local street network characteristics may have statistically significant effects on geocoding accuracy in some places, but not others. Even in those locales where their effects are statistically significant, street network characteristics may explain a relatively small portion of the variability among geocoding errors. It appears that additional factors besides rurality and local street network characteristics affect accuracy in general.

The Relationship of Policymaking and Networking Characteristics among Leaders of Large Urban Health Departments.

Science.gov (United States)

Leider, Jonathon P; Castrucci, Brian C; Harris, Jenine K; Hearne, Shelley

2015-08-06

The relationship between policy networks and policy development among local health departments (LHDs) is a growing area of interest to public health practitioners and researchers alike. In this study, we examine policy activity and ties between public health leadership across large urban health departments. This study uses data from a national profile of local health departments as well as responses from a survey sent to three staff members (local health official, chief of policy, chief science officer) in each of 16 urban health departments in the United States. Network questions related to frequency of contact with health department personnel in other cities. Using exponential random graph models, network density and centrality were examined, as were patterns of communication among those working on several policy areas using exponential random graph models. All 16 LHDs were active in communicating about chronic disease as well as about use of alcohol, tobacco, and other drugs (ATOD). Connectedness was highest among local health officials (density = .55), and slightly lower for chief science officers (d = .33) and chiefs of policy (d = .29). After accounting for organizational characteristics, policy homophily (i.e., when two network members match on a single characteristic) and tenure were the most significant predictors of formation of network ties. Networking across health departments has the potential for accelerating the adoption of public health policies. This study suggests similar policy interests and formation of connections among senior leadership can potentially drive greater connectedness among other staff.

Network meta-analyses performed by contracting companies and commissioned by industry

NARCIS (Netherlands)

Schuit, Ewoud; Ioannidis, John P A

2016-01-01

Background: Industry commissions contracting companies to perform network meta-analysis for health technology assessment (HTA) and reimbursement submissions. Our objective was to estimate the number of network meta-analyses performed by consulting companies contracted by industry, to assess whether

The Influence of Social Network Characteristics on Peer Clustering in Smoking: A Two-Wave Panel Study of 19- and 23-Year-Old Swedes.

Science.gov (United States)

Miething, Alexander; Rostila, Mikael; Edling, Christofer; Rydgren, Jens

2016-01-01

The present study examines how the composition of social networks and perceived relationship content influence peer clustering in smoking, and how the association changes during the transition from late adolescence to early adulthood. The analysis was based on a Swedish two-wave survey sample comprising ego-centric network data. Respondents were 19 years old in the initial wave, and 23 when the follow-up sample was conducted. 17,227 ego-alter dyads were included in the analyses, which corresponds to an average response rate of 48.7 percent. Random effects logistic regression models were performed to calculate gender-specific average marginal effects of social network characteristics on smoking. The association of egos' and alters' smoking behavior was confirmed and found to be stronger when correlated in the female sample. For females, the associations decreased between age 19 and 23. Interactions between network characteristics and peer clustering in smoking showed that intense social interactions with smokers increase egos' smoking probability. The influence of network structures on peer clustering in smoking decreased during the transition from late adolescence to early adulthood. The study confirmed peer clustering in smoking and revealed that females' smoking behavior in particular is determined by social interactions. Female smokers' propensity to interact with other smokers was found to be associated with the quality of peer relationships, frequent social interactions, and network density. The influence of social networks on peer clustering in smoking decreased during the transition from late adolescence to early adulthood.

Network analysis of patient flow in two UK acute care hospitals identifies key sub-networks for A&E performance.

Science.gov (United States)

Bean, Daniel M; Stringer, Clive; Beeknoo, Neeraj; Teo, James; Dobson, Richard J B

2017-01-01

The topology of the patient flow network in a hospital is complex, comprising hundreds of overlapping patient journeys, and is a determinant of operational efficiency. To understand the network architecture of patient flow, we performed a data-driven network analysis of patient flow through two acute hospital sites of King's College Hospital NHS Foundation Trust. Administration databases were queried for all intra-hospital patient transfers in an 18-month period and modelled as a dynamic weighted directed graph. A 'core' subnetwork containing only 13-17% of all edges channelled 83-90% of the patient flow, while an 'ephemeral' network constituted the remainder. Unsupervised cluster analysis and differential network analysis identified sub-networks where traffic is most associated with A&E performance. Increased flow to clinical decision units was associated with the best A&E performance in both sites. The component analysis also detected a weekend effect on patient transfers which was not associated with performance. We have performed the first data-driven hypothesis-free analysis of patient flow which can enhance understanding of whole healthcare systems. Such analysis can drive transformation in healthcare as it has in industries such as manufacturing.

Effects of Network Characteristics on Reaching the Payoff-Dominant Equilibrium in Coordination Games: A Simulation study.

Science.gov (United States)

Buskens, Vincent; Snijders, Chris

2016-01-01

We study how payoffs and network structure affect reaching the payoff-dominant equilibrium in a [Formula: see text] coordination game that actors play with their neighbors in a network. Using an extensive simulation analysis of over 100,000 networks with 2-25 actors, we show that the importance of network characteristics is restricted to a limited part of the payoff space. In this part, we conclude that the payoff-dominant equilibrium is chosen more often if network density is larger, the network is more centralized, and segmentation of the network is smaller. Moreover, it is more likely that heterogeneity in behavior persists if the network is more segmented and less centralized. Persistence of heterogeneous behavior is not related to network density.

Tuning mechanical performance of poly(ethylene glycol) and agarose interpenetrating network hydrogels for cartilage tissue engineering.

Science.gov (United States)

Rennerfeldt, Deena A; Renth, Amanda N; Talata, Zsolt; Gehrke, Stevin H; Detamore, Michael S

2013-11-01

Hydrogels are attractive for tissue engineering applications due to their incredible versatility, but they can be limited in cartilage tissue engineering applications due to inadequate mechanical performance. In an effort to address this limitation, our team previously reported the drastic improvement in the mechanical performance of interpenetrating networks (IPNs) of poly(ethylene glycol) diacrylate (PEG-DA) and agarose relative to pure PEG-DA and agarose networks. The goal of the current study was specifically to determine the relative importance of PEG-DA concentration, agarose concentration, and PEG-DA molecular weight in controlling mechanical performance, swelling characteristics, and network parameters. IPNs consistently had compressive and shear moduli greater than the additive sum of either single network when compared to pure PEG-DA gels with a similar PEG-DA content. IPNs withstood a maximum stress of up to 4.0 MPa in unconfined compression, with increased PEG-DA molecular weight being the greatest contributing factor to improved failure properties. However, aside from failure properties, PEG-DA concentration was the most influential factor for the large majority of properties. Increasing the agarose and PEG-DA concentrations as well as the PEG-DA molecular weight of agarose/PEG-DA IPNs and pure PEG-DA gels improved moduli and maximum stresses by as much as an order of magnitude or greater compared to pure PEG-DA gels in our previous studies. Although the viability of encapsulated chondrocytes was not significantly affected by IPN formulation, glycosaminoglycan (GAG) content was significantly influenced, with a 12-fold increase over a three-week period in gels with a lower PEG-DA concentration. These results suggest that mechanical performance of IPNs may be tuned with partial but not complete independence from biological performance of encapsulated cells. © 2013 Elsevier Ltd. All rights reserved.

Design, deployment and performance of 4G-LTE networks a practical approach

CERN Document Server

ElNashar, Ayman; Sherif, Mahmoud

2014-01-01

This book provides an insight into the key practical aspects and best practice of 4G-LTE network design, performance, and deployment Design, Deployment and Performance of 4G-LTE Networks addresses the key practical aspects and best practice of 4G networks design, performance, and deployment. In addition, the book focuses on the end-to-end aspects of the LTE network architecture and different deployment scenarios of commercial LTE networks. It describes the air interface of LTE focusing on the access stratum protocol layers: PDCP, RLC, MAC, and Physical Layer. The air interface described in this book covers the concepts of LTE frame structure, downlink and uplink scheduling, and detailed illustrations of the data flow across the protocol layers. It describes the details of the optimization process including performance measurements and troubleshooting mechanisms in addition to demonstrating common issues and case studies based on actual field results. The book provides detailed performance analysis of key fe...

Nonlinear Performance Characteristics of Flux-Switching PM Motors

Directory of Open Access Journals (Sweden)

E. Ilhan

2013-01-01

Full Text Available Nonlinear performance characteristics of 3-phase flux-switching permanent magnet motors (FSPM are overviewed. These machines show advantages of a robust rotor structure and a high energy density. Research on the FSPM is predominated by topics such as modeling and machine comparison, with little emphasis given on its performance and limits. Performance characteristics include phase flux linkage, phase torque, and phase inductance. In the paper, this analysis is done by a cross-correlation of rotor position and armature current. Due to the high amount of processed data, which cannot be handled analytically within an acceptable time period, a multistatic 2D finite element model (FEM is used. For generalization, the most commonly discussed FSPM topology, 12/10 FSPM, is chosen. Limitations on the motor performance due to the saturation are discussed on each characteristic. Additionally, a focused overview is given on energy conversion loops and dq-axes identification for the FSPM.

Mitigating the controller performance bottlenecks in Software Defined Networks

DEFF Research Database (Denmark)

Caba, Cosmin Marius; Soler, José

2016-01-01

The centralization of the control plane decision logic in Software Defined Networking (SDN) has raised concerns regarding the performance of the SDN Controller (SDNC) when the network scales up. A number of solutions have been proposed in the literature to address these concerns. This paper...

Investigation of Hybrid Pseudo Bipolar HVDC Performances Supply Power to Passive AC Network

Directory of Open Access Journals (Sweden)

Kuan Li

2014-07-01

Full Text Available The traditional HVDC plays an important role in the development of power grid. But the traditional HVDC cannot supply power either to entirely passive AC network or to weak AC system. In fact, an entirely passive AC network can be effectively powered through VSC-HVDC. However, the cost of investment in VSC-HVDC is amazingly high due to the limitation of power electronics technology. Based on CSC and VSC, this paper proposes a method to build Hybrid HVDC, which makes the power supply to the passive AC network come true and, at the same time, lowers the investment cost. The effect of topology, steady mathematical model, startup characteristic, steady and transient characteristics in Hybrid HVDC system are systematically studied in this paper. The simulation result shows that Hybrid HVDC can supply power to the passive AC network with high stability. This study provides a theoretical basis for the further development of HVDC.

Performance analysis and improvement of WPAN MAC for home networks.

Science.gov (United States)

Mehta, Saurabh; Kwak, Kyung Sup

2010-01-01

The wireless personal area network (WPAN) is an emerging wireless technology for future short range indoor and outdoor communication applications. The IEEE 802.15.3 medium access control (MAC) is proposed to coordinate the access to the wireless medium among the competing devices, especially for short range and high data rate applications in home networks. In this paper we use analytical modeling to study the performance analysis of WPAN (IEEE 802.15.3) MAC in terms of throughput, efficient bandwidth utilization, and delay with various ACK policies under error channel condition. This allows us to introduce a K-Dly-ACK-AGG policy, payload size adjustment mechanism, and Improved Backoff algorithm to improve the performance of the WPAN MAC. Performance evaluation results demonstrate the impact of our improvements on network capacity. Moreover, these results can be very useful to WPAN application designers and protocol architects to easily and correctly implement WPAN for home networking.

Performance Analysis and Improvement of WPAN MAC for Home Networks

Directory of Open Access Journals (Sweden)

Saurabh Mehta

2010-03-01

Full Text Available The wireless personal area network (WPAN is an emerging wireless technology for future short range indoor and outdoor communication applications. The IEEE 802.15.3 medium access control (MAC is proposed to coordinate the access to the wireless medium among the competing devices, especially for short range and high data rate applications in home networks. In this paper we use analytical modeling to study the performance analysis of WPAN (IEEE 802.15.3 MAC in terms of throughput, efficient bandwidth utilization, and delay with various ACK policies under error channel condition. This allows us to introduce a K-Dly-ACK-AGG policy, payload size adjustment mechanism, and Improved Backoff algorithm to improve the performance of the WPAN MAC. Performance evaluation results demonstrate the impact of our improvements on network capacity. Moreover, these results can be very useful to WPAN application designers and protocol architects to easily and correctly implement WPAN for home networking.

Performance evaluation of a high-speed switched network for PACS

Science.gov (United States)

Zhang, Randy H.; Tao, Wenchao; Huang, Lu J.; Valentino, Daniel J.

1998-07-01

We have replaced our shared-media Ethernet and FDDI network with a multi-tiered, switched network using OC-12 (622 Mbps) ATM for the network backbone, OC3 (155 Mbps) connections to high-end servers and display workstations, and switched 100/10 Mbps Ethernet for workstations and desktop computers. The purpose of this research was to help PACS designers and implementers understand key performance factors in a high- speed switched network by characterizing and evaluating its image delivery performance, specifically, the performance of socket-based TCP (Transmission Control Protocol) and DICOM 3.0 communications. A test network within the UCLA Clinical RIS/PACS was constructed using Sun UltraSPARC-II machines with ATM, Fast Ethernet, and Ethernet network interfaces. To identify performance bottlenecks, we evaluated network throughput for memory to memory, memory to disk, disk to memory, and disk to disk transfers. To evaluate the effect of file size, tests involving disks were further divided using sizes of small (514 KB), medium (8 MB), and large (16 MB) files. The observed maximum throughput for various network configurations using the TCP protocol was 117 Mbps for memory to memory and 88 MBPS for memory to disk. For disk to memory, the peak throughput was 98 Mbps using small files, 114 Mbps using medium files, and 116 Mbps using large files. The peak throughput for disk to disk became 64 Mbps using small files and 96 Mbps using medium and large files. The peak throughput using the DICOM 3.0 protocol was substantially lower in all categories. The measured throughput varied significantly among the tests when TCP socket buffer was raised above the default value. The optimal buffer size was approximately 16 KB or the TCP protocol and around 256 KB for the DICOM protocol. The application message size also displayed distinctive effects on network throughput when the TCP socket buffer size was varied. The throughput results for Fast Ethernet and Ethernet were expectedly

Sustainable Performance in Energy Harvesting - Wireless Sensor Networks

DEFF Research Database (Denmark)

Fafoutis, Xenofon; Di Mauro, Alessio; Dragoni, Nicola

2013-01-01

In this practical demo we illustrate the concept of "sustainable performance" in Energy-Harvesting Wireless Sensor Networks (EH-WSNs). In particular, for different classes of applications and under several energy harvesting scenarios, we show how it is possible to have sustainable performance when...

Improvement of Networked Control Systems Performance Using a New Encryption Algorithm

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Seyed Ali Mesbahifard

2014-07-01

Full Text Available Networked control systems are control systems which controllers and plants are connected via telecommunication network. One of the most important challenges in networked control systems is the problem of network time delay. Increasing of time delay may affect on control system performance extremely. Other important issue in networked control systems is the security problems. Since it is possible that unknown people access to network especially Internet, the probability of terrible attacks such as deception attacks is greater, therefore presentation of methods which could decrease time delay and increase system immunity are desired. In this paper a symmetric encryption with low data volume against deception attacks is proposed. This method has high security and low time delay rather than the other encryption algorithms and could improve the control system performance against deception attacks.

Performance modeling, stochastic networks, and statistical multiplexing

CERN Document Server

Mazumdar, Ravi R

2013-01-01

This monograph presents a concise mathematical approach for modeling and analyzing the performance of communication networks with the aim of introducing an appropriate mathematical framework for modeling and analysis as well as understanding the phenomenon of statistical multiplexing. The models, techniques, and results presented form the core of traffic engineering methods used to design, control and allocate resources in communication networks.The novelty of the monograph is the fresh approach and insights provided by a sample-path methodology for queueing models that highlights the importan

PERFORMANCE COMPARISON FOR INTRUSION DETECTION SYSTEM USING NEURAL NETWORK WITH KDD DATASET

Directory of Open Access Journals (Sweden)

S. Devaraju

2014-04-01

Full Text Available Intrusion Detection Systems are challenging task for finding the user as normal user or attack user in any organizational information systems or IT Industry. The Intrusion Detection System is an effective method to deal with the kinds of problem in networks. Different classifiers are used to detect the different kinds of attacks in networks. In this paper, the performance of intrusion detection is compared with various neural network classifiers. In the proposed research the four types of classifiers used are Feed Forward Neural Network (FFNN, Generalized Regression Neural Network (GRNN, Probabilistic Neural Network (PNN and Radial Basis Neural Network (RBNN. The performance of the full featured KDD Cup 1999 dataset is compared with that of the reduced featured KDD Cup 1999 dataset. The MATLAB software is used to train and test the dataset and the efficiency and False Alarm Rate is measured. It is proved that the reduced dataset is performing better than the full featured dataset.

Analyzing the impact of relay station characteristics on uplink performance in cellular network

NARCIS (Netherlands)

Dimitrova, D.C.; van den Berg, Hans Leo; Heijenk, Geert

2009-01-01

Uplink users in cellular networks, such as UMTS/ HSPA, located at the edge of the cell generally suffer from poor channel conditions. Deploying intermediate relay nodes is seen as a promising approach towards extending cell coverage. This paper focuses on the role of packet scheduling in cellular

The Relationship of Policymaking and Networking Characteristics among Leaders of Large Urban Health Departments

Directory of Open Access Journals (Sweden)

Jonathon P. Leider

2015-08-01

Full Text Available Background: The relationship between policy networks and policy development among local health departments (LHDs is a growing area of interest to public health practitioners and researchers alike. In this study, we examine policy activity and ties between public health leadership across large urban health departments. Methods: This study uses data from a national profile of local health departments as well as responses from a survey sent to three staff members (local health official, chief of policy, chief science officer in each of 16 urban health departments in the United States. Network questions related to frequency of contact with health department personnel in other cities. Using exponential random graph models, network density and centrality were examined, as were patterns of communication among those working on several policy areas using exponential random graph models. Results: All 16 LHDs were active in communicating about chronic disease as well as about use of alcohol, tobacco, and other drugs (ATOD. Connectedness was highest among local health officials (density = .55, and slightly lower for chief science officers (d = .33 and chiefs of policy (d = .29. After accounting for organizational characteristics, policy homophily (i.e., when two network members match on a single characteristic and tenure were the most significant predictors of formation of network ties. Conclusion: Networking across health departments has the potential for accelerating the adoption of public health policies. This study suggests similar policy interests and formation of connections among senior leadership can potentially drive greater connectedness among other staff.

Performance of WLAN RSS-based SON for LTE/WLAN access network selection

NARCIS (Netherlands)

Wang, Y.; Djapic, R.; Bergström, A.; Kovács, I.Z.; Laselva, D.; Spaey, K.; Sas, B.

2014-01-01

Mobile Network Operators (MNOs) are integrating carrier-grade Wireless Local Area Network (WLAN) to cellular networks to improve network performance and user experience. Access network selection (ANS) between cellular and WLAN plays a key role in the integration. Given the complexity of

Prediction of vibration characteristics of a planar mechanism having imperfect joints using neural network

International Nuclear Information System (INIS)

Erkaya, Selcuk

2012-01-01

Clearance is inevitable in the joints of mechanisms due primarily to the design, manufacturing and assembly processes or a wear effect. Excessive value of joint clearance plays a crucial role and has a significant effect on the kinematic and dynamic performances of the mechanism. In this study, effects of joint clearances on bearing vibrations of mechanism are investigated. An experimental test rig is set up, and a planar slider-crank mechanism having two imperfect joints with radial clearance is used as a model mechanism. Three accelerometers are positioned at different points to measure the bearing vibrations during the mechanism motion. For the different running speeds and clearance sizes, this work provides a neural model to predict and estimate the bearing vibrations of the mechanical systems having imperfect joints. The results show that radial basis function (RBF) neural network has a superior performance for predicting and estimating the vibration characteristics of the mechanical system

Towards a Social Networks Model for Online Learning & Performance

Science.gov (United States)

Chung, Kon Shing Kenneth; Paredes, Walter Christian

2015-01-01

In this study, we develop a theoretical model to investigate the association between social network properties, "content richness" (CR) in academic learning discourse, and performance. CR is the extent to which one contributes content that is meaningful, insightful and constructive to aid learning and by social network properties we…

A Framework to Implement IoT Network Performance Modelling Techniques for Network Solution Selection.

Science.gov (United States)

Delaney, Declan T; O'Hare, Gregory M P

2016-12-01

No single network solution for Internet of Things (IoT) networks can provide the required level of Quality of Service (QoS) for all applications in all environments. This leads to an increasing number of solutions created to fit particular scenarios. Given the increasing number and complexity of solutions available, it becomes difficult for an application developer to choose the solution which is best suited for an application. This article introduces a framework which autonomously chooses the best solution for the application given the current deployed environment. The framework utilises a performance model to predict the expected performance of a particular solution in a given environment. The framework can then choose an apt solution for the application from a set of available solutions. This article presents the framework with a set of models built using data collected from simulation. The modelling technique can determine with up to 85% accuracy the solution which performs the best for a particular performance metric given a set of solutions. The article highlights the fractured and disjointed practice currently in place for examining and comparing communication solutions and aims to open a discussion on harmonising testing procedures so that different solutions can be directly compared and offers a framework to achieve this within IoT networks.

A Framework to Implement IoT Network Performance Modelling Techniques for Network Solution Selection

Directory of Open Access Journals (Sweden)

Declan T. Delaney

2016-12-01

Full Text Available No single network solution for Internet of Things (IoT networks can provide the required level of Quality of Service (QoS for all applications in all environments. This leads to an increasing number of solutions created to fit particular scenarios. Given the increasing number and complexity of solutions available, it becomes difficult for an application developer to choose the solution which is best suited for an application. This article introduces a framework which autonomously chooses the best solution for the application given the current deployed environment. The framework utilises a performance model to predict the expected performance of a particular solution in a given environment. The framework can then choose an apt solution for the application from a set of available solutions. This article presents the framework with a set of models built using data collected from simulation. The modelling technique can determine with up to 85% accuracy the solution which performs the best for a particular performance metric given a set of solutions. The article highlights the fractured and disjointed practice currently in place for examining and comparing communication solutions and aims to open a discussion on harmonising testing procedures so that different solutions can be directly compared and offers a framework to achieve this within IoT networks.

Predicting Expressive Dynamics in Piano Performances using Neural Networks

NARCIS (Netherlands)

van Herwaarden, Sam; Grachten, Maarten; de Haas, W. Bas

2014-01-01

This paper presents a model for predicting expressive accentuation in piano performances with neural networks. Using Restricted Boltzmann Machines (RBMs), features are learned from performance data, after which these features are used to predict performed loudness. During feature learning, data

Growth performance, carcass and hematological characteristics of ...

African Journals Online (AJOL)

Growth performance, carcass and hematological characteristics of rabbits fed graded levels of tiger nuts ( Cyperus esculentus ) ... (p>0.05) difference between treatments. Results demonstrated that (Cyperus esculentus) could be used up to 5% in rabbit's diets without adverse effect on the animals' performance and health.

Deep Recurrent Convolutional Neural Network: Improving Performance For Speech Recognition

OpenAIRE

Zhang, Zewang; Sun, Zheng; Liu, Jiaqi; Chen, Jingwen; Huo, Zhao; Zhang, Xiao

2016-01-01

A deep learning approach has been widely applied in sequence modeling problems. In terms of automatic speech recognition (ASR), its performance has significantly been improved by increasing large speech corpus and deeper neural network. Especially, recurrent neural network and deep convolutional neural network have been applied in ASR successfully. Given the arising problem of training speed, we build a novel deep recurrent convolutional network for acoustic modeling and then apply deep resid...

A general framework for performance guaranteed green data center networking

OpenAIRE

Wang, Ting; Xia, Yu; Muppala, Jogesh; Hamdi, Mounir; Foufou, Sebti

2014-01-01

From the perspective of resource allocation and routing, this paper aims to save as much energy as possible in data center networks. We present a general framework, based on the blocking island paradigm, to try to maximize the network power conservation and minimize sacrifices of network performance and reliability. The bandwidth allocation mechanism together with power-aware routing algorithm achieve a bandwidth guaranteed tighter network. Besides, our fast efficient heuristics for allocatin...

Influence of current pulse shape on directly modulated system performance in metro area optical networks

Science.gov (United States)

Campos, Carmina del Rio; Horche, Paloma R.; Martin-Minguez, Alfredo

2011-03-01

Due to the fact that a metro network market is very cost sensitive, direct modulated schemes appear attractive. In this paper a CWDM (Coarse Wavelength Division Multiplexing) system is studied in detail by means of an Optical Communication System Design Software; a detailed study of the modulated current shape (exponential, sine and gaussian) for 2.5 Gb/s CWDM Metropolitan Area Networks is performed to evaluate its tolerance to linear impairments such as signal-to-noise-ratio degradation and dispersion. Point-to-point links are investigated and optimum design parameters are obtained. Through extensive sets of simulation results, it is shown that some of these shape pulses are more tolerant to dispersion when compared with conventional gaussian shape pulses. In order to achieve a low Bit Error Rate (BER), different types of optical transmitters are considered including strongly adiabatic and transient chirp dominated Directly Modulated Lasers (DMLs). We have used fibers with different dispersion characteristics, showing that the system performance depends, strongly, on the chosen DML-fiber couple.

Anti-correlations in the degree distribution increase stimulus detection performance in noisy spiking neural networks.

Science.gov (United States)

Martens, Marijn B; Houweling, Arthur R; E Tiesinga, Paul H

2017-02-01

Neuronal circuits in the rodent barrel cortex are characterized by stable low firing rates. However, recent experiments show that short spike trains elicited by electrical stimulation in single neurons can induce behavioral responses. Hence, the underlying neural networks provide stability against internal fluctuations in the firing rate, while simultaneously making the circuits sensitive to small external perturbations. Here we studied whether stability and sensitivity are affected by the connectivity structure in recurrently connected spiking networks. We found that anti-correlation between the number of afferent (in-degree) and efferent (out-degree) synaptic connections of neurons increases stability against pathological bursting, relative to networks where the degrees were either positively correlated or uncorrelated. In the stable network state, stimulation of a few cells could lead to a detectable change in the firing rate. To quantify the ability of networks to detect the stimulation, we used a receiver operating characteristic (ROC) analysis. For a given level of background noise, networks with anti-correlated degrees displayed the lowest false positive rates, and consequently had the highest stimulus detection performance. We propose that anti-correlation in the degree distribution may be a computational strategy employed by sensory cortices to increase the detectability of external stimuli. We show that networks with anti-correlated degrees can in principle be formed by applying learning rules comprised of a combination of spike-timing dependent plasticity, homeostatic plasticity and pruning to networks with uncorrelated degrees. To test our prediction we suggest a novel experimental method to estimate correlations in the degree distribution.

Social networks and small businesses performance in West African border regions

DEFF Research Database (Denmark)

Kuépié, Mathias; Tenikue, Michel; Walther, Olivier

2016-01-01

burden that leads to a negative economic impact. Testing the effect of social networks between small traders and three categories of actors, we find that the most well-connected actors are also the most successful in terms of monthly profit. The effects of social networks are, however, dependent...... with traditional religious leaders has a negative effect on economic performance. Our work has two implications: first, collecting data on social networks remains challenging due to endogeneity. Second, network-enhancing policies should aim at improving both the internal connectivity of economic actors......This paper studies the link between economic performance and social networks in West Africa. Using data collected about 358 small-scale traders in five border markets, we show that social network can simultaneously be a resource which positively contributes to labor market outcomes and a social...

Integrated network design and scheduling problems :

Energy Technology Data Exchange (ETDEWEB)

Nurre, Sarah G.; Carlson, Jeffrey J.

2014-01-01

We consider the class of integrated network design and scheduling problems. These problems focus on selecting and scheduling operations that will change the characteristics of a network, while being speci cally concerned with the performance of the network over time. Motivating applications of INDS problems include infrastructure restoration after extreme events and building humanitarian distribution supply chains. While similar models have been proposed, no one has performed an extensive review of INDS problems from their complexity, network and scheduling characteristics, information, and solution methods. We examine INDS problems under a parallel identical machine scheduling environment where the performance of the network is evaluated by solving classic network optimization problems. We classify that all considered INDS problems as NP-Hard and propose a novel heuristic dispatching rule algorithm that selects and schedules sets of arcs based on their interactions in the network. We present computational analysis based on realistic data sets representing the infrastructures of coastal New Hanover County, North Carolina, lower Manhattan, New York, and a realistic arti cial community CLARC County. These tests demonstrate the importance of a dispatching rule to arrive at near-optimal solutions during real-time decision making activities. We extend INDS problems to incorporate release dates which represent the earliest an operation can be performed and exible release dates through the introduction of specialized machine(s) that can perform work to move the release date earlier in time. An online optimization setting is explored where the release date of a component is not known.

Performance benefits and limitations of a camera network

Science.gov (United States)

Carr, Peter; Thomas, Paul J.; Hornsey, Richard

2005-06-01

Visual information is of vital significance to both animals and artificial systems. The majority of mammals rely on two images, each with a resolution of 107-108 'pixels' per image. At the other extreme are insect eyes where the field of view is segmented into 103-105 images, each comprising effectively one pixel/image. The great majority of artificial imaging systems lie nearer to the mammalian characteristics in this parameter space, although electronic compound eyes have been developed in this laboratory and elsewhere. If the definition of a vision system is expanded to include networks or swarms of sensor elements, then schools of fish, flocks of birds and ant or termite colonies occupy a region where the number of images and the pixels/image may be comparable. A useful system might then have 105 imagers, each with about 104-105 pixels. Artificial analogs to these situations include sensor webs, smart dust and co-ordinated robot clusters. As an extreme example, we might consider the collective vision system represented by the imminent existence of ~109 cellular telephones, each with a one-megapixel camera. Unoccupied regions in this resolution-segmentation parameter space suggest opportunities for innovative artificial sensor network systems. Essential for the full exploitation of these opportunities is the availability of custom CMOS image sensor chips whose characteristics can be tailored to the application. Key attributes of such a chip set might include integrated image processing and control, low cost, and low power. This paper compares selected experimentally determined system specifications for an inward-looking array of 12 cameras with the aid of a camera-network model developed to explore the tradeoff between camera resolution and the number of cameras.

A performance analysis of DS-CDMA and SCPC VSAT networks

Science.gov (United States)

Hayes, David P.; Ha, Tri T.

1990-01-01

Spread-spectrum and single-channel-per-carrier (SCPC) transmission techniques work well in very small aperture terminal (VSAT) networks for multiple-access purposes while allowing the earth station antennas to remain small. Direct-sequence code-division multiple-access (DS-CDMA) is the simplest spread-spectrum technique to use in a VSAT network since a frequency synthesizer is not required for each terminal. An examination is made of the DS-CDMA and SCPC Ku-band VSAT satellite systems for low-density (64-kb/s or less) communications. A method for improving the standardf link analysis of DS-CDMA satellite-switched networks by including certain losses is developed. The performance of 50-channel full mesh and star network architectures is analyzed. The selection of operating conditions producing optimum performance is demonstrated.

Investigation of road network features and safety performance.

Science.gov (United States)

Wang, Xuesong; Wu, Xingwei; Abdel-Aty, Mohamed; Tremont, Paul J

2013-07-01

The analysis of road network designs can provide useful information to transportation planners as they seek to improve the safety of road networks. The objectives of this study were to compare and define the effective road network indices and to analyze the relationship between road network structure and traffic safety at the level of the Traffic Analysis Zone (TAZ). One problem in comparing different road networks is establishing criteria that can be used to scale networks in terms of their structures. Based on data from Orange and Hillsborough Counties in Florida, road network structural properties within TAZs were scaled using 3 indices: Closeness Centrality, Betweenness Centrality, and Meshedness Coefficient. The Meshedness Coefficient performed best in capturing the structural features of the road network. Bayesian Conditional Autoregressive (CAR) models were developed to assess the safety of various network configurations as measured by total crashes, crashes on state roads, and crashes on local roads. The models' results showed that crash frequencies on local roads were closely related to factors within the TAZs (e.g., zonal network structure, TAZ population), while crash frequencies on state roads were closely related to the road and traffic features of state roads. For the safety effects of different networks, the Grid type was associated with the highest frequency of crashes, followed by the Mixed type, the Loops & Lollipops type, and the Sparse type. This study shows that it is possible to develop a quantitative scale for structural properties of a road network, and to use that scale to calculate the relationships between network structural properties and safety. Copyright © 2013 Elsevier Ltd. All rights reserved.

Understanding characteristics in multivariate traffic flow time series from complex network structure

Science.gov (United States)

Yan, Ying; Zhang, Shen; Tang, Jinjun; Wang, Xiaofei

2017-07-01

Discovering dynamic characteristics in traffic flow is the significant step to design effective traffic managing and controlling strategy for relieving traffic congestion in urban cities. A new method based on complex network theory is proposed to study multivariate traffic flow time series. The data were collected from loop detectors on freeway during a year. In order to construct complex network from original traffic flow, a weighted Froenius norm is adopt to estimate similarity between multivariate time series, and Principal Component Analysis is implemented to determine the weights. We discuss how to select optimal critical threshold for networks at different hour in term of cumulative probability distribution of degree. Furthermore, two statistical properties of networks: normalized network structure entropy and cumulative probability of degree, are utilized to explore hourly variation in traffic flow. The results demonstrate these two statistical quantities express similar pattern to traffic flow parameters with morning and evening peak hours. Accordingly, we detect three traffic states: trough, peak and transitional hours, according to the correlation between two aforementioned properties. The classifying results of states can actually represent hourly fluctuation in traffic flow by analyzing annual average hourly values of traffic volume, occupancy and speed in corresponding hours.

A performance study of unmanned aerial vehicle-based sensor networks under cyber attack

Science.gov (United States)

Puchaty, Ethan M.

In UAV-based sensor networks, an emerging area of interest is the performance of these networks under cyber attack. This study seeks to evaluate the performance trade-offs from a System-of-Systems (SoS) perspective between various UAV communications architecture options in the context two missions: tracking ballistic missiles and tracking insurgents. An agent-based discrete event simulation is used to model a sensor communication network consisting of UAVs, military communications satellites, ground relay stations, and a mission control center. Network susceptibility to cyber attack is modeled with probabilistic failures and induced data variability, with performance metrics focusing on information availability, latency, and trustworthiness. Results demonstrated that using UAVs as routers increased network availability with a minimal latency penalty and communications satellite networks were best for long distance operations. Redundancy in the number of links between communication nodes helped mitigate cyber-caused link failures and add robustness in cases of induced data variability by an adversary. However, when failures were not independent, redundancy and UAV routing were detrimental in some cases to network performance. Sensitivity studies indicated that long cyber-caused downtimes and increasing failure dependencies resulted in build-ups of failures and caused significant degradations in network performance.

On the Tradeoff between Performance and Programmability for Software Defined WiFi Networks

Directory of Open Access Journals (Sweden)

Tausif Zahid

2018-01-01

Full Text Available WiFi has become one of the major network access networks due to its simple technical implementation and high-bandwidth provisioning. In this paper, we studied software defined WiFi networks (SDWN against traditional WiFi networks to understand the potential benefits, such as the ability of SDWN to effectively hide the handover delay between access points (AP of the adoption of the SDWN architecture on WiFi networks and identify representative application scenarios where such SDWN approach could bring additional benefits. This study delineated the performance bottlenecks such as the throughput degradation by around 50% compared with the conventional WiFi networks. In addition, our study also shed some insights into performance optimization issues. All of the performance measurements were conducted on a network testbed consisting of a single basic service set (BSS and an extended service set (ESS managed by a single SDN controller deployed with various laboratory settings. Our evaluation included the throughput performance under different traffic loads with different number of nodes and packet sizes for both TCP and UDP traffic flows. Handover delays were measured during the roaming phase between different APs against the traditional WiFi networks. Our results have demonstrated the tradeoff between performance and programmability of software defined APs.

Is functional integration of resting state brain networks an unspecific biomarker for working memory performance?

Science.gov (United States)

Alavash, Mohsen; Doebler, Philipp; Holling, Heinz; Thiel, Christiane M; Gießing, Carsten

2015-03-01

Is there one optimal topology of functional brain networks at rest from which our cognitive performance would profit? Previous studies suggest that functional integration of resting state brain networks is an important biomarker for cognitive performance. However, it is still unknown whether higher network integration is an unspecific predictor for good cognitive performance or, alternatively, whether specific network organization during rest predicts only specific cognitive abilities. Here, we investigated the relationship between network integration at rest and cognitive performance using two tasks that measured different aspects of working memory; one task assessed visual-spatial and the other numerical working memory. Network clustering, modularity and efficiency were computed to capture network integration on different levels of network organization, and to statistically compare their correlations with the performance in each working memory test. The results revealed that each working memory aspect profits from a different resting state topology, and the tests showed significantly different correlations with each of the measures of network integration. While higher global network integration and modularity predicted significantly better performance in visual-spatial working memory, both measures showed no significant correlation with numerical working memory performance. In contrast, numerical working memory was superior in subjects with highly clustered brain networks, predominantly in the intraparietal sulcus, a core brain region of the working memory network. Our findings suggest that a specific balance between local and global functional integration of resting state brain networks facilitates special aspects of cognitive performance. In the context of working memory, while visual-spatial performance is facilitated by globally integrated functional resting state brain networks, numerical working memory profits from increased capacities for local processing

Network Congestion and Performance Management

OpenAIRE

Shewmaker, Andrew Glenn

2016-01-01

We increasingly depend on well-behaved networks in the course of every-day activities for business, community, government, science, and recreation. And with more people demanding a greater variety of services comes sharp disagreement about which needs are most important. Unfortunately, today’s technology is inadequate to guarantee the performance of dynamic and diverse workloads in such a way that we are prevented from hurting each other’s goals.No one likes waiting in traffic, whether on a r...

Performance evaluation of spatial vector routing protocol for wireless sensor networks

International Nuclear Information System (INIS)

Baloch, J.; Jokhio, I.

2012-01-01

WSNs (Wireless Sensor Networks) is an emerging area of research. Researchers worldwide are working on the issues faced by sensor nodes. Communication has been a major issue in wireless networks and the problem is manifolds in WSN s because of the limited resources. The routing protocol in such networks plays a pivotal role, as an effective routing protocol could significantly reduce the energy consumed in transmitting and receiving data packets throughout a network. In this paper the performance of SVR (Spatial Vector Routing) an energy efficient, location aware routing protocol is compared with the existing location aware protocols. The results from the simulation trials show the performance of SVR. (author)

Performance Evaluation of Spatial Vector Routing Protocol for Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Javed Ali Baloch

2012-10-01

Full Text Available WSNs (Wireless Sensor Networks is an emerging area of research. Researchers worldwide are working on the issues faced by sensor nodes. Communication has been a major issue in wireless networks and the problem is manifolds in WSNs because of the limited resources. The routing protocol in such networks plays a pivotal role, as an effective routing protocol could significantly reduce the energy consumed in transmitting and receiving data packets throughout a network. In this paper the performance of SVR (Spatial Vector Routing an energy efficient, location aware routing protocol is compared with the existing location aware protocols. The results from the simulation trials show the performance of SVR.

Performance of highly connected photonic switching lossless metro-access optical networks

Science.gov (United States)

Martins, Indayara Bertoldi; Martins, Yara; Barbosa, Felipe Rudge

2018-03-01

The present work analyzes the performance of photonic switching networks, optical packet switching (OPS) and optical burst switching (OBS), in mesh topology of different sizes and configurations. The "lossless" photonic switching node is based on a semiconductor optical amplifier, demonstrated and validated with experimental results on optical power gain, noise figure, and spectral range. The network performance was evaluated through computer simulations based on parameters such as average number of hops, optical packet loss fraction, and optical transport delay (Am). The combination of these elements leads to a consistent account of performance, in terms of network traffic and packet delivery for OPS and OBS metropolitan networks. Results show that a combination of highly connected mesh topologies having an ingress e-buffer present high efficiency and throughput, with very low packet loss and low latency, ensuring fast data delivery to the final receiver.

Communication, opponents, and clan performance in online games: a social network approach.

Science.gov (United States)

Lee, Hong Joo; Choi, Jaewon; Kim, Jong Woo; Park, Sung Joo; Gloor, Peter

2013-12-01

Online gamers form clans voluntarily to play together and to discuss their real and virtual lives. Although these clans have diverse goals, they seek to increase their rank in the game community by winning more battles. Communications among clan members and battles with other clans may influence the performance of a clan. In this study, we compared the effects of communication structure inside a clan, and battle networks among clans, with the performance of the clans. We collected battle histories, posts, and comments on clan pages from a Korean online game, and measured social network indices for communication and battle networks. Communication structures in terms of density and group degree centralization index had no significant association with clan performance. However, the centrality of clans in the battle network was positively related to the performance of the clan. If a clan had many battle opponents, the performance of the clan improved.

Triangulation positioning system network

Directory of Open Access Journals (Sweden)

Sfendourakis Marios

2017-01-01

Full Text Available This paper presents ongoing work on localization and positioning through triangulation procedure for a Fixed Sensors Network - FSN.The FSN has to work as a system.As the triangulation problem becomes high complicated in a case with large numbers of sensors and transmitters, an adequate grid topology is needed in order to tackle the detection complexity.For that reason a Network grid topology is presented and areas that are problematic and need further analysis are analyzed.The Network System in order to deal with problems of saturation and False Triangulations - FTRNs will have to find adequate methods in every sub-area of the Area Of Interest - AOI.Also, concepts like Sensor blindness and overall Network blindness, are presented. All these concepts affect the Network detection rate and its performance and ought to be considered in a way that the network overall performance won’t be degraded.Network performance should be monitored contentiously, with right algorithms and methods.It is also shown that as the number of TRNs and FTRNs is increased Detection Complexity - DC is increased.It is hoped that with further research all the characteristics of a triangulation system network for positioning will be gained and the system will be able to perform autonomously with a high detection rate.

Characteristic Length Scales in Fracture Networks: Hydraulic Connectivity through Periodic Hydraulic Tests

Science.gov (United States)

Becker, M.; Bour, O.; Le Borgne, T.; Longuevergne, L.; Lavenant, N.; Cole, M. C.; Guiheneuf, N.

2017-12-01

Determining hydraulic and transport connectivity in fractured bedrock has long been an important objective in contaminant hydrogeology, petroleum engineering, and geothermal operations. A persistent obstacle to making this determination is that the characteristic length scale is nearly impossible to determine in sparsely fractured networks. Both flow and transport occur through an unknown structure of interconnected fracture and/or fracture zones making the actual length that water or solutes travel undetermined. This poses difficulties for flow and transport models. For, example, hydraulic equations require a separation distance between pumping and observation well to determine hydraulic parameters. When wells pairs are close, the structure of the network can influence the interpretation of well separation and the flow dimension of the tested system. This issue is explored using hydraulic tests conducted in a shallow fractured crystalline rock. Periodic (oscillatory) slug tests were performed at the Ploemeur fractured rock test site located in Brittany, France. Hydraulic connectivity was examined between three zones in one well and four zones in another, located 6 m apart in map view. The wells are sufficiently close, however, that the tangential distance between the tested zones ranges between 6 and 30 m. Using standard periodic formulations of radial flow, estimates of storativity scale inversely with the square of the separation distance and hydraulic diffusivity directly with the square of the separation distance. Uncertainty in the connection paths between the two wells leads to an order of magnitude uncertainty in estimates of storativity and hydraulic diffusivity, although estimates of transmissivity are unaffected. The assumed flow dimension results in alternative estimates of hydraulic parameters. In general, one is faced with the prospect of assuming the hydraulic parameter and inverting the separation distance, or vice versa. Similar uncertainties exist

Full-Duplex MIMO Small-Cell Networks: Performance Analysis

OpenAIRE

Atzeni, Italo; Kountouris, Marios

2015-01-01

Full-duplex small-cell relays with multiple antennas constitute a core element of the envisioned 5G network architecture. In this paper, we use stochastic geometry to analyze the performance of wireless networks with full-duplex multiple-antenna small cells, with particular emphasis on the probability of successful transmission. To achieve this goal, we additionally characterize the distribution of the self-interference power of the full-duplex nodes. The proposed framework reveals useful ins...

Network characteristics and open innovation in SMEs

DEFF Research Database (Denmark)

Pedersen, Maja; Søndergaard, Helle Alsted; Esbjerg, Lars

The open innovation literature has primarily been concentrating on open innovation (OI) in large companies. Hence it is very unclear whether these findings can be generalized to small and medium-sized enterprises (SMEs). This paper begins filling in this knowledge gap. In doing so, we focus...... explicitly on understanding network characteristics and the unfolding of OI in SMEs. Case studies were used and empirical data was mainly generated through semi-structured interviews. Cases selected for study were companies in the Danish food industry with less than 499 employees. In this paper we report our...... findings for four cases. Our study shows that companies with a relatively open innovation process have both strong and weak ties with external partners. Companies with a relatively more closed innovation process have on the other hand only few weak ties and no strong ties with external partners....

Evaluating Flight Crew Performance by a Bayesian Network Model

Directory of Open Access Journals (Sweden)

Wei Chen

2018-03-01

Full Text Available Flight crew performance is of great significance in keeping flights safe and sound. When evaluating the crew performance, quantitative detailed behavior information may not be available. The present paper introduces the Bayesian Network to perform flight crew performance evaluation, which permits the utilization of multidisciplinary sources of objective and subjective information, despite sparse behavioral data. In this paper, the causal factors are selected based on the analysis of 484 aviation accidents caused by human factors. Then, a network termed Flight Crew Performance Model is constructed. The Delphi technique helps to gather subjective data as a supplement to objective data from accident reports. The conditional probabilities are elicited by the leaky noisy MAX model. Two ways of inference for the BN—probability prediction and probabilistic diagnosis are used and some interesting conclusions are drawn, which could provide data support to make interventions for human error management in aviation safety.

NetBench. Automated Network Performance Testing

CERN Document Server

Cadeddu, Mattia

2016-01-01

In order to evaluate the operation of high performance routers, CERN has developed the NetBench software to run benchmarking tests by injecting various traffic patterns and observing the network devices behaviour in real-time. The tool features a modular design with a Python based console used to inject traffic and collect the results in a database, and a web user

Performability indicators for the traffic analysis of wide area networks

International Nuclear Information System (INIS)

Tsopelas, Panagiotis; Platis, Agapios

2003-01-01

In connecting computing networks, reliability term is strongly related to the availability of connections of Wide Area networks (WANs) or Local Area networks (LANs). In this paper we will examine the network connections activity of a Greek University in order to provide two sources of information: The Quantity of Information Not Delivered (QIND) and the Information Flow Interruption (IFI). These indicators will provide us with the inference of information from observable characteristics of data flow(s), even when the data is encrypted or otherwise not directly available (traffic), which is lost due to failures or upgrades inside this network. The reliability analysis is obtained by collecting the network failures data (duration and frequency) and traffic (total and average) for a specified period of 1 year. It is assumed that the numerical analysis is based on the fact that the lifetime follows and exponential distribution (here as we are working on discrete time the distribution must be the geometric distribution). Hence a Markov chain model seems suitable for modelling the functioning of this system. An algorithm concentrates the results in a transition probability matrix and calculates the reward functions for the QIND/IFI indicators with the use of the power method. Finally, the application part provides an example of how final results can be used to evaluate the observed network

Outage and ser performance of an opportunistic multi-user underlay cognitive network

KAUST Repository

Khan, Fahd Ahmed

2012-10-01

Consider a multi-user underlay cognitive network where multiple cognitive users concurrently share the spectrum with a primary network and a single secondary user is selected for transmission. The channel is assumed to have independent but not identical Nakagami-m fading. Closed form expressions for the outage performance and the symbol-error-rate performance of the opportunistic multi-user secondary network are derived when a peak interference power constraint is imposed on the secondary network in addition to the limited peak transmit power of each secondary user. © 2012 IEEE.

An investigation of 'sparse channel networks'. Characteristic behaviours and their causes

Energy Technology Data Exchange (ETDEWEB)

Black, J.H. (In Situ Solutions, East Bridgford (GB)); Barker, J.A.; Woodman, N.D. (Univ. of Southampton (GB))

2007-09-15

This report represents a third study in a series concerned with groundwater flow in poorly permeable fractured crystalline rocks. The study has brought together three linked, but distinct, elements; a mathematical analysis of the intersection of ellipses, a review of field measurements associated with nuclear waste repository investigations and probabilistic simulations using a lattice network numerical model. We conclude that the model of channels that traverse fracture intersections without necessarily branching is a very likely representation of reality. More generally, assembling all the lines of evidence, it is suggested that groundwater flow systems in fractured crystalline rocks in the environs of underground laboratories have the following characteristics: Groundwater flows within a sparse network of channels just above the percolation limit. The frequency of intersections is low in that individual channels extend considerable distances between significant junctions. Individual channels often extend over many fracture surfaces and the resulting flow system is only weakly related to the density or size of mappable fractures. The sparseness of systems compared to the size of drifts and tunnels means that only a very few flow channels are intersected by drifts and tunnels. Highly convergent flow is required to connect to the rest of the network and this is misinterpreted as a skin of low hydraulic conductivity. Systems are so sparse that they are controlled by a few 'chokes' that give rise to compartments of head, and probably, of groundwater chemistry. Channels occur on all fracture planes, including those within fracture zones, and although the characteristics of the fracture zone channel networks may differ from those in surrounding rocks, they are nonetheless still channel networks. The actively flowing sparse channel network, occurring within any particular rock, is a naturally selected, small sub-set of the available channels. Hence, there are

LTE, WiMAX and WLAN network design, optimization and performance analysis

CERN Document Server

Korowajczuk, Leonhard

2011-01-01

A technological overview of LTE and WiMAX LTE, WiMAX and WLAN Network Design, Optimization and Performance Analysis provides a practical guide to LTE and WiMAX technologies introducing various tools and concepts used within. In addition, topics such as traffic modelling of IP-centric networks, RF propagation, fading, mobility, and indoor coverage are explored; new techniques which increase throughput such as MIMO and AAS technology are highlighted; and simulation, network design and performance analysis are also examined. Finally, in the latter part of the book Korowajczuk gives a step-by-step

Topology and computational performance of attractor neural networks

International Nuclear Information System (INIS)

McGraw, Patrick N.; Menzinger, Michael

2003-01-01

To explore the relation between network structure and function, we studied the computational performance of Hopfield-type attractor neural nets with regular lattice, random, small-world, and scale-free topologies. The random configuration is the most efficient for storage and retrieval of patterns by the network as a whole. However, in the scale-free case retrieval errors are not distributed uniformly among the nodes. The portion of a pattern encoded by the subset of highly connected nodes is more robust and efficiently recognized than the rest of the pattern. The scale-free network thus achieves a very strong partial recognition. The implications of these findings for brain function and social dynamics are suggestive

The Impact of Social Networks on Students’ Performance

Directory of Open Access Journals (Sweden)

Jusuf Zekiri

2016-11-01

Full Text Available The objective of this study is to determine the impact of using social media and its impact on students’ performance and success. This research tries to identify the relationship between students’ use of social networks and their success in their studies. It tries also to find out whether time spent impacts students’ performance and success. Whether students use social media more for entertainment or for teaching and information sharing purposes. The paper uses a quantitative approach for collecting the primary data. The data was collected by surveying 255 respondents from South East European University. The data analyses were done by SPSS so" ware program. Cronbach alpha is used for testing the validity and reliability of variables used in this study. The hypotheses were tested using One Simple T-test. The obtained empirical results show that a great number of students are aware of advantages and disadvantages by the social media. Thus, due to a great percent of times spent on social networking activities, the performance and the success of students suffer setbacks which could lead to a poor performance and they might fail to create a balance between the social media and academic activities. Furthermore, it is about their addiction, the loss of time leading to consequences in their academic development, and they are also influenced to a great extent negatively by the social networking sites, because their attention is focused on chatting and music while their academic activities are neglected. Finally, based on the results of survey, we can conclude that impact of social media on the academic performance of students should focus more on the positive side than on the negative side to achieve balance. Hence, creating more pages for research and academic activities will enable students to improve their performance, thereby avoiding a distraction which leads to deviation from their academic work.

Passive performance monitoring and traffic characteristics on the SLAC internet border

International Nuclear Information System (INIS)

Logg, C.; Cottrell, L.

2001-01-01

Understanding how the Internet is used by HEP is critical to optimizing the performance of the inter-lab computing environment. Typically use requirements have been defined by discussions between collaborators. However, later analysis of the actual traffic has show this is often misunderstood and actual use is significantly different to that predicted. Passive monitoring of the real traffic provides insight into the true communications requirements and the performance of a large number of inter-communicating nodes. It may be useful in identifying performance problems that are due to factors other than Internet congestion, especially when compared to other methods such as active monitoring where traffic is generated specifically to measure its performance. Controlled active monitoring between dedicated servers often gives an indication of what can be achieved on a network. Passive monitoring of the real traffic gives a picture of the true performance. The authors will discuss the method and results of collecting and analyzing flows of data obtained from the SLAC Internet border. The insights this has brought to understanding the network will be reviewed and the benefit it can bring to engineering networks will be discussed

Performers and performance : how to investigate the contribution of the operational network to operational performance

NARCIS (Netherlands)

Wijngaard, J.; Vries, J. de; Nauta, A.

2006-01-01

Purpose This paper seeks to explore the question of how to investigate the contribution of the operational network (comprising sales service, logistics, planning, production, etc.) to operational performance. In doing so, the paper aims to link concepts from organisational and social psychology to

Performers and performance : How to investigate the contribution of the operational network to operational performance

NARCIS (Netherlands)

Wijngaard, J.; de Vries, J.; Nauta, Aukje

2006-01-01

Purpose - This paper seeks to explore the question of how to investigate the contribution of the operational network (comprising sales service, logistics, planning, production, etc.) to operational performance. In doing so, the paper aims to link concepts from organisational and social psychology to

Small Worlds in the Tree Topologies of Wireless Sensor Networks

DEFF Research Database (Denmark)

Qiao, Li; Lingguo, Cui; Baihai, Zhang

2010-01-01

In this study, the characteristics of small worlds are investigated in the context of the tree topologies of wireless sensor networks. Tree topologies, which construct spatial graphs with larger characteristic path lengths than random graphs and small clustering coefficients, are ubiquitous...... in wireless sensor networks. Suffering from the link rewiring or the link addition, the characteristic path length of the tree topology reduces rapidly and the clustering coefficient increases greatly. The variety of characteristic path length influences the time synchronization characteristics of wireless...... sensor networks greatly. With the increase of the link rewiring or the link addition probability, the time synchronization error decreases drastically. Two novel protocols named LEACH-SW and TREEPSI-SW are proposed to improve the performances of the sensor networks, in which the small world...

Covariance of engineering management characteristics with engineering employee performance

Science.gov (United States)

Hesketh, Andrew Arthur

1998-12-01

As business in the 1990's grapples with the impact of continuous improvement and quality to meet market demands, there is an increased need to improve the leadership capabilities of our managers. Engineers have indicated desire for certain managerial characteristics in their leadership but there have been no studies completed that approached the problem of determining what managerial characteristics were best at improving employee performance. This study addressed the idea of identifying certain managerial characteristics that enhance employee performance. In the early 1990's, McDonnell Douglas Aerospace in St. Louis used a forced distribution system and allocated 35% of its employees into a "exceeds expectations" category and 60% into a "meets expectations" category. A twenty-question 5 point Likert scale survey on managerial capabilities was administered to a sample engineering population that also obtained their "expectations" category. A single factor ANOVA on the survey results determined a statistical difference between the "exceeds" and "meets" employees with four of the managerial capability questions. The "exceeds expectations" employee indicated that supervision did a better job of supporting subordinate development, clearly communicating performance expectations, and providing timely performance feedback when compared to the "meets expectations" employee. The "meets expectations" employee felt that their opinions, when different from their supervisor's, were more often ignored when compared to the "exceeds expectations" employee. These four questions relate to two specific managerial characteristics, "gaining (informal) authority and support" or "control" characteristic and "providing assistance and guidance" or "command" characteristic, that can be emphasized in managerial training programs.

Performance analysis of WS-EWC coded optical CDMA networks with/without LDPC codes

Science.gov (United States)

Huang, Chun-Ming; Huang, Jen-Fa; Yang, Chao-Chin

2010-10-01

One extended Welch-Costas (EWC) code family for the wavelength-division-multiplexing/spectral-amplitude coding (WDM/SAC; WS) optical code-division multiple-access (OCDMA) networks is proposed. This system has a superior performance as compared to the previous modified quadratic congruence (MQC) coded OCDMA networks. However, since the performance of such a network is unsatisfactory when the data bit rate is higher, one class of quasi-cyclic low-density parity-check (QC-LDPC) code is adopted to improve that. Simulation results show that the performance of the high-speed WS-EWC coded OCDMA network can be greatly improved by using the LDPC codes.

Performance in wireless networks and industrial wireless networks on control processes in real time under industrial environments

Directory of Open Access Journals (Sweden)

Juan F. Monsalve-Posada

2015-01-01

Full Text Available The growing use of Ethernet networks on the industrial automation pyramid has led many companies to develop new devices to operate in requirements of this level, nowadays it is called Industrial Ethernet network, on the market there are various sensors and actuators to industrial scale equipped with this technology, many of these devices are very expensive. In this paper, the performance of two wireless networks is evaluated, the first network has conventional Ethernet devices, and the second network has Industrial Ethernet devices. For the process we vary four parameters such as distance, number of bytes, the signal to noise ratio, and the packet error rate, and then we measure delays and compare with metric statistics results, Box Plot graphs were used for the analysis. Finally, we conclude that under the parameters and conditions tested, wireless networks can serve as a communication system in control applications with allowable delays of up to 50 ms, in addition, the results show a better performance of Industrial Ethernet networks over conventional networks, with differences in the RTT of milliseconds. Therefore, it is recommended to establish what risk is for the process to control these delays to determine if the equipment conventional applies, since under certain features like humidity and temperature can operate properly for a considerable time and at lower cost than devices to Industrial Ethernet.

The performance evaluation of a new neural network based traffic management scheme for a satellite communication network

Science.gov (United States)

Ansari, Nirwan; Liu, Dequan

1991-01-01

A neural-network-based traffic management scheme for a satellite communication network is described. The scheme consists of two levels of management. The front end of the scheme is a derivation of Kohonen's self-organization model to configure maps for the satellite communication network dynamically. The model consists of three stages. The first stage is the pattern recognition task, in which an exemplar map that best meets the current network requirements is selected. The second stage is the analysis of the discrepancy between the chosen exemplar map and the state of the network, and the adaptive modification of the chosen exemplar map to conform closely to the network requirement (input data pattern) by means of Kohonen's self-organization. On the basis of certain performance criteria, whether a new map is generated to replace the original chosen map is decided in the third stage. A state-dependent routing algorithm, which arranges the incoming call to some proper path, is used to make the network more efficient and to lower the call block rate. Simulation results demonstrate that the scheme, which combines self-organization and the state-dependent routing mechanism, provides better performance in terms of call block rate than schemes that only have either the self-organization mechanism or the routing mechanism.

Evaluation of knowledge management performances in NULIFE network

International Nuclear Information System (INIS)

Nitoi, Mirela; Cojan, Mihai; Pavelescu, Margarit

2009-01-01

One of the objectives of Nuclear Plant Life Prediction (NULIFE) network is the identification of experts and resources which can be used in the future. The major challenge is to use these competent personnel in an efficient manner, in the network. The paper presents the necessity of developing the knowledge management strategy for networks of excellence, as the specific issues of NULIFE network. In order to highlight the progress during the project operating, the developed indicators of performance are specified. The developed questionnaires evaluate the quality of knowledge management (development, use and distribution of knowledge), type of knowledge which is considered important for organization (at present and in future) and the benefits of knowledge transfer (immediate and in perspective). The developed questionnaires permit along with the evaluation of others groups activities, an auto-evaluation for the activity of the group where the subject is involved. (authors)

An evaluation of current high-performance networks

Energy Technology Data Exchange (ETDEWEB)

Bell, Christian; Bonachea, Dan; Cote, Yannick; Duell, Jason; Hargrove, Paul; Husbands, Parry; Iancu, Costin; Welcome, Michael; Yelick, Katherine

2003-01-25

High-end supercomputers are increasingly built out of commodity components, and lack tight integration between the processor and network. This often results in inefficiencies in the communication subsystem, such as high software overheads and/or message latencies. In this paper we use a set of microbenchmarks to quantify the cost of this commoditization, measuring software overhead, latency, and bandwidth on five contemporary supercomputing networks. We compare the performance of the ubiquitous MPI layer to that of lower-level communication layers, and quantify the advantages of the latter for small message performance. We also provide data on the potential for various communication-related optimizations, such as overlapping communication with computation or other communication. Finally, we determine the minimum size needed for a message to be considered 'large' (i.e., bandwidth-bound) on these platforms, and provide historical data on the software overheads of a number of supercomputers over the past decade.

Multicast Performance Analysis for High-Speed Torus Networks

National Research Council Canada - National Science Library

Oral, S; George, A

2002-01-01

... for unicast-based and path-based multicast communication on high-speed torus networks. Software-based multicast performance results of selected algorithms on a 16-node Scalable Coherent Interface (SCI) torus are given...

The influence of passenger flow on the topology characteristics of urban rail transit networks

Science.gov (United States)

Hu, Yingyue; Chen, Feng; Chen, Peiwen; Tan, Yurong

2017-05-01

Current researches on the network characteristics of metro networks are generally carried out on topology networks without passenger flows running on it, thus more complex features of the networks with ridership loaded on it cannot be captured. In this study, we incorporated the load of metro networks, passenger volume, into the exploration of network features. Thus, the network can be examined in the context of operation, which is the ultimate purpose of the existence of a metro network. To this end, section load was selected as an edge weight to demonstrate the influence of ridership on the network, and a weighted calculation method for complex network indicators and robustness were proposed to capture the unique behaviors of a metro network with passengers flowing in it. The proposed method was applied on Beijing Subway. Firstly, the passenger volume in terms of daily origin and destination matrix was extracted from exhausted transit smart card data. Using the established approach and the matrix as weighting, common indicators of complex network including clustering coefficient, betweenness and degree were calculated, and network robustness were evaluated under potential attacks. The results were further compared to that of unweighted networks, and it suggests indicators of the network with consideration of passenger volumes differ from that without ridership to some extent, and networks tend to be more vulnerable than that without load on it. The significance sequence for the stations can be changed. By introducing passenger flow weighting, actual operation status of the network can be reflected more accurately. It is beneficial to determine the crucial stations and make precautionary measures for the entire network’s operation security.

Personal Network Characteristics as Predictors of Change in Obesity Risk Behaviors in Early Adolescence.

Science.gov (United States)

Marks, Jennifer; de la Haye, Kayla; Barnett, Lisa M; Allender, Steven

2018-05-17

The potential for peers to influence obesity risk behavior increases in adolescence, yet there are knowledge gaps of how behaviors are modified in response to peers over time. This study examined how personal friendship network characteristics were associated with obesity-related behaviors from late childhood to early adolescence. Two waves of friendship, physical activity, screen time, and dietary recall data were collected from 11- to 13-year-old students (99% retention) in Australia (n = 308) over a five- to eight-month period. Regression models identified friendship network characteristics that predicted later health behaviors which varied by gender and behavior type, such as the number of friends positively associated with physical activity intensity (males) and screen time (females). The need for considering context to influence behavior change is discussed. © 2018 Society for Research on Adolescence.

Network characteristics emerging from agent interactions in balanced distributed system.

Science.gov (United States)

Salman, Mahdi Abed; Bertelle, Cyrille; Sanlaville, Eric

2015-01-01

A distributed computing system behaves like a complex network, the interactions between nodes being essential information exchanges and migrations of jobs or services to execute. These actions are performed by software agents, which behave like the members of social networks, cooperating and competing to obtain knowledge and services. The load balancing consists in distributing the load evenly between system nodes. It aims at enhancing the resource usage. A load balancing strategy specifies scenarios for the cooperation. Its efficiency depends on quantity, accuracy, and distribution of available information. Nevertheless, the distribution of information on the nodes, together with the initial network structure, may create different logical network structures. In this paper, different load balancing strategies are tested on different network structures using a simulation. The four tested strategies are able to distribute evenly the load so that the system reaches a steady state (the mean response time of the jobs is constant), but it is shown that a given strategy indeed behaves differently according to structural parameters and information spreading. Such a study, devoted to distributed computing systems (DCSs), can be useful to understand and drive the behavior of other complex systems.

Performance and complexity of tunable sparse network coding with gradual growing tuning functions over wireless networks

OpenAIRE

Garrido Ortiz, Pablo; Sørensen, Chres W.; Lucani Roetter, Daniel Enrique; Agüero Calvo, Ramón

2016-01-01

Random Linear Network Coding (RLNC) has been shown to be a technique with several benefits, in particular when applied over wireless mesh networks, since it provides robustness against packet losses. On the other hand, Tunable Sparse Network Coding (TSNC) is a promising concept, which leverages a trade-off between computational complexity and goodput. An optimal density tuning function has not been found yet, due to the lack of a closed-form expression that links density, performance and comp...

Performance Analysis of Cell-Phone Worm Spreading in Cellular Networks through Opportunistic Communications

Directory of Open Access Journals (Sweden)

YAHUI, W.

2012-05-01

Full Text Available Worms spreading directly between cell-phones over short-range radio (Bluetooth, WiFi, etc. are increasing rapidly. Communication by these technologies is opportunistic and has very close relation with the social characteristics of the phone carriers. In this paper, we try to evaluate the impact of different characteristics on the spreading performance of worms. On the other hand, the behaviors of worms may have certain impact, too. For example, worms may make phones be completely dysfunctional and these phones can be seen as killed. We study the impact of the killing speed. Using the Markov model, we propose some theoretical models to evaluate the spreading performance in different cases. Simulation results show the accuracy of our models. Numerical results show that if users do not believe the data coming from others easily, the worms may bring less damage. Surprisingly, if the users are more willing to install the anti-virus software, the worms may bring bigger damage when the software becomes to be outdated with high probability. Though the worms can bring big damage on the network temporarily by killing phones rapidly, numerical results show that this behavior may decrease the total damage in the long time. Therefore, killing nodes more rapidly may be not optimal for worms.

Identifying the relevant dependencies of the neural network response on characteristics of the input space

CERN Multimedia

CERN. Geneva

2018-01-01

This talk presents an approach to identify those characteristics of the neural network inputs that are most relevant for the response and therefore provides essential information to determine the systematic uncertainties.

Visualizing weighted networks: a performance comparison of adjacency matrices versus node-link diagrams

Science.gov (United States)

McIntire, John P.; Osesina, O. Isaac; Bartley, Cecilia; Tudoreanu, M. Eduard; Havig, Paul R.; Geiselman, Eric E.

2012-06-01

Ensuring the proper and effective ways to visualize network data is important for many areas of academia, applied sciences, the military, and the public. Fields such as social network analysis, genetics, biochemistry, intelligence, cybersecurity, neural network modeling, transit systems, communications, etc. often deal with large, complex network datasets that can be difficult to interact with, study, and use. There have been surprisingly few human factors performance studies on the relative effectiveness of different graph drawings or network diagram techniques to convey information to a viewer. This is particularly true for weighted networks which include the strength of connections between nodes, not just information about which nodes are linked to other nodes. We describe a human factors study in which participants performed four separate network analysis tasks (finding a direct link between given nodes, finding an interconnected node between given nodes, estimating link strengths, and estimating the most densely interconnected nodes) on two different network visualizations: an adjacency matrix with a heat-map versus a node-link diagram. The results should help shed light on effective methods of visualizing network data for some representative analysis tasks, with the ultimate goal of improving usability and performance for viewers of network data displays.

The enhancing impact of friendship networks on sales managers' performance

OpenAIRE

Claro, Danny Pimentel; Laban Neto, Silvio Abrahão; Claro, Priscila Borin de Oliveira

2013-01-01

This paper examines how relationships with friends moderate the impact of professional networks on sales performance. Based on a sample of 204 sales managers in a professional service company, this study presents evidence that friendship networks amplify the effect of sales forces’ professional networks on new product sales as well as on prospecting and converting new deals. Our results offer important insights into the socio-cognitive perspective of sales management literature and suggest th...

Evaluating the Impact of Communication Network Performance on Supervisory Supermarket Control

DEFF Research Database (Denmark)

Madsen, Jacob Theilgaard; Minko, Tomasz; Madsen, Tatiana Kozlova

2017-01-01

This paper addresses the evaluation of the impact of non-ideal communication networks on system performance of hierarchical control systems. It develops a stepwise evaluation approach that is applied to the example scenario of a supervisory controller for supermarket temperature control, addressing...... of communication network performance on the supermarket refrigeration control and resulting energy costs using simulation models. The results show that the controller is resilient to downstream information delays, however upstream delays or up- and downstream information loss can cause significant performance...

LEARNING ALGORITHM EFFECT ON MULTILAYER FEED FORWARD ARTIFICIAL NEURAL NETWORK PERFORMANCE IN IMAGE CODING

Directory of Open Access Journals (Sweden)

OMER MAHMOUD

2007-08-01

Full Text Available One of the essential factors that affect the performance of Artificial Neural Networks is the learning algorithm. The performance of Multilayer Feed Forward Artificial Neural Network performance in image compression using different learning algorithms is examined in this paper. Based on Gradient Descent, Conjugate Gradient, Quasi-Newton techniques three different error back propagation algorithms have been developed for use in training two types of neural networks, a single hidden layer network and three hidden layers network. The essence of this study is to investigate the most efficient and effective training methods for use in image compression and its subsequent applications. The obtained results show that the Quasi-Newton based algorithm has better performance as compared to the other two algorithms.

The Gain of Performance of Optical WDM Networks

Directory of Open Access Journals (Sweden)

Miroslav Bahleda

2008-01-01

Full Text Available We study the blocking probability and performance of single-fiber and multifiber optical networks with wavelength division multiplexing (WDM. We extend the well-known analytical blocking probability model by Barry and Humblet to the general model, which is proposed for both single-fiber and multifiber network paths with any kind of wavelength conversion (no, limited, or full wavelength conversion and for uniform and nonuniform link loads. We investigate the effect of the link load, wavelength conversion degree, and the number of wavelengths, fibers, and hops on blocking probability. We also extend the definition of the gain of wavelength conversion by Barry and Humblet to the gain of performance, which is fully general. Thanks to this definition and implementation of our model, we compare different WDM node architectures and present interesting results.

Influence of course characteristics, student characteristics, and behavior in learning management systems on student performance

OpenAIRE

Conijn, Rianne; Kleingeld, Ad; Matzat, Uwe; Snijders, Chris; van Zaanen, Menno

2016-01-01

The use of learning management systems (LMS) in education make it possible to track students’ online behavior. This data can be used for educational data mining and learning analytics, for example, by predicting student performance. Although LMS data might contain useful predictors, course characteristics and student characteristics have shown to influence student performance as well. However, these different sets of features are rarely combined or compared. Therefore, in the current study we...

The Impact of Increases in Subsidiary Autonomy and Network Relationships on Performance

DEFF Research Database (Denmark)

Gammelgaard, Jens; McDonald, Frank; Stephan, Andreas

2012-01-01

This paper uses network approaches to subsidiary theory to investigate the performance impacts of interactions among the factors of autonomy, intra-organizational network relationships, and inter-organizational network relationships. The paper offers an analysis of both direct and indirect intera...

Performance Parameters Analysis of an XD3P Peugeot Engine Using Artificial Neural Networks (ANN) Concept in MATLAB

Science.gov (United States)

Rangaswamy, T.; Vidhyashankar, S.; Madhusudan, M.; Bharath Shekar, H. R.

2015-04-01

The current trends of engineering follow the basic rule of innovation in mechanical engineering aspects. For the engineers to be efficient, problem solving aspects need to be viewed in a multidimensional perspective. One such methodology implemented is the fusion of technologies from other disciplines in order to solve the problems. This paper mainly deals with the application of Neural Networks in order to analyze the performance parameters of an XD3P Peugeot engine (used in Ministry of Defence). The basic propaganda of the work is divided into two main working stages. In the former stage, experimentation of an IC engine is carried out in order to obtain the primary data. In the latter stage the primary database formed is used to design and implement a predictive neural network in order to analyze the output parameters variation with respect to each other. A mathematical governing equation for the neural network is obtained. The obtained polynomial equation describes the characteristic behavior of the built neural network system. Finally, a comparative study of the results is carried out.

The effects of working memory training on functional brain network efficiency.

Science.gov (United States)

Langer, Nicolas; von Bastian, Claudia C; Wirz, Helen; Oberauer, Klaus; Jäncke, Lutz

2013-10-01

The human brain is a highly interconnected network. Recent studies have shown that the functional and anatomical features of this network are organized in an efficient small-world manner that confers high efficiency of information processing at relatively low connection cost. However, it has been unclear how the architecture of functional brain networks is related to performance in working memory (WM) tasks and if these networks can be modified by WM training. Therefore, we conducted a double-blind training study enrolling 66 young adults. Half of the subjects practiced three WM tasks and were compared to an active control group practicing three tasks with low WM demand. High-density resting-state electroencephalography (EEG) was recorded before and after training to analyze graph-theoretical functional network characteristics at an intracortical level. WM performance was uniquely correlated with power in the theta frequency, and theta power was increased by WM training. Moreover, the better a person's WM performance, the more their network exhibited small-world topology. WM training shifted network characteristics in the direction of high performers, showing increased small-worldness within a distributed fronto-parietal network. Taken together, this is the first longitudinal study that provides evidence for the plasticity of the functional brain network underlying WM. Copyright © 2013 Elsevier Ltd. All rights reserved.

A Holistic Approach to ZigBee Performance Enhancement for Home Automation Networks

Directory of Open Access Journals (Sweden)

August Betzler

2014-08-01

Full Text Available Wireless home automation networks are gaining importance for smart homes. In this ambit, ZigBee networks play an important role. The ZigBee specification defines a default set of protocol stack parameters and mechanisms that is further refined by the ZigBee Home Automation application profile. In a holistic approach, we analyze how the network performance is affected with the tuning of parameters and mechanisms across multiple layers of the ZigBee protocol stack and investigate possible performance gains by implementing and testing alternative settings. The evaluations are carried out in a testbed of 57 TelosB motes. The results show that considerable performance improvements can be achieved by using alternative protocol stack configurations. From these results, we derive two improved protocol stack configurations for ZigBee wireless home automation networks that are validated in various network scenarios. In our experiments, these improved configurations yield a relative packet delivery ratio increase of up to 33.6%, a delay decrease of up to 66.6% and an improvement of the energy efficiency for battery powered devices of up to 48.7%, obtainable without incurring any overhead to the network.

A Holistic Approach to ZigBee Performance Enhancement for Home Automation Networks

Science.gov (United States)

Betzler, August; Gomez, Carles; Demirkol, Ilker; Paradells, Josep

2014-01-01

Wireless home automation networks are gaining importance for smart homes. In this ambit, ZigBee networks play an important role. The ZigBee specification defines a default set of protocol stack parameters and mechanisms that is further refined by the ZigBee Home Automation application profile. In a holistic approach, we analyze how the network performance is affected with the tuning of parameters and mechanisms across multiple layers of the ZigBee protocol stack and investigate possible performance gains by implementing and testing alternative settings. The evaluations are carried out in a testbed of 57 TelosB motes. The results show that considerable performance improvements can be achieved by using alternative protocol stack configurations. From these results, we derive two improved protocol stack configurations for ZigBee wireless home automation networks that are validated in various network scenarios. In our experiments, these improved configurations yield a relative packet delivery ratio increase of up to 33.6%, a delay decrease of up to 66.6% and an improvement of the energy efficiency for battery powered devices of up to 48.7%, obtainable without incurring any overhead to the network. PMID:25196004

A holistic approach to ZigBee performance enhancement for home automation networks.

Science.gov (United States)

Betzler, August; Gomez, Carles; Demirkol, Ilker; Paradells, Josep

2014-08-14

Wireless home automation networks are gaining importance for smart homes. In this ambit, ZigBee networks play an important role. The ZigBee specification defines a default set of protocol stack parameters and mechanisms that is further refined by the ZigBee Home Automation application profile. In a holistic approach, we analyze how the network performance is affected with the tuning of parameters and mechanisms across multiple layers of the ZigBee protocol stack and investigate possible performance gains by implementing and testing alternative settings. The evaluations are carried out in a testbed of 57 TelosB motes. The results show that considerable performance improvements can be achieved by using alternative protocol stack configurations. From these results, we derive two improved protocol stack configurations for ZigBee wireless home automation networks that are validated in various network scenarios. In our experiments, these improved configurations yield a relative packet delivery ratio increase of up to 33.6%, a delay decrease of up to 66.6% and an improvement of the energy efficiency for battery powered devices of up to 48.7%, obtainable without incurring any overhead to the network.

Photonic network-on-chip design

CERN Document Server

Bergman, Keren; Biberman, Aleksandr; Chan, Johnnie; Hendry, Gilbert

2013-01-01

This book provides a comprehensive synthesis of the theory and practice of photonic devices for networks-on-chip. It outlines the issues in designing photonic network-on-chip architectures for future many-core high performance chip multiprocessors. The discussion is built from the bottom up: starting with the design and implementation of key photonic devices and building blocks, reviewing networking and network-on-chip theory and existing research, and finishing with describing various architectures, their characteristics, and the impact they will have on a computing system. After acquainting

Performance assessment of air quality monitoring networks using principal component analysis and cluster analysis

International Nuclear Information System (INIS)

Lu, Wei-Zhen; He, Hong-Di; Dong, Li-yun

2011-01-01

This study aims to evaluate the performance of two statistical methods, principal component analysis and cluster analysis, for the management of air quality monitoring network of Hong Kong and the reduction of associated expenses. The specific objectives include: (i) to identify city areas with similar air pollution behavior; and (ii) to locate emission sources. The statistical methods were applied to the mass concentrations of sulphur dioxide (SO 2 ), respirable suspended particulates (RSP) and nitrogen dioxide (NO 2 ), collected in monitoring network of Hong Kong from January 2001 to December 2007. The results demonstrate that, for each pollutant, the monitoring stations are grouped into different classes based on their air pollution behaviors. The monitoring stations located in nearby area are characterized by the same specific air pollution characteristics and suggested with an effective management of air quality monitoring system. The redundant equipments should be transferred to other monitoring stations for allowing further enlargement of the monitored area. Additionally, the existence of different air pollution behaviors in the monitoring network is explained by the variability of wind directions across the region. The results imply that the air quality problem in Hong Kong is not only a local problem mainly from street-level pollutions, but also a region problem from the Pearl River Delta region. (author)

NM-Net Gigabit-based Implementation on Core Network Facilities and Performance Design Hierarchy

International Nuclear Information System (INIS)

Raja Murzaferi Raja Moktar; Mohd Fauzi Haris; Siti Nurbahyah Hamdan

2013-01-01

Nuclear Malaysia computing network or NM-net has been gradually developed since 1990s. Since then it has been the main backbone of inter networking on agency's IT infrastructure, serving users ranging from researchers to operational staffs. Main network operating center or NOC is situated in Block 15 and linkup via fiber or UTP cabling to adjacent main network blocks (18, 29, 11 and 44-Dengkil) and later to other blocks enabling network connections. In 2009 the main core network has been built up form several switches up link to form the main networking switch, while on the adjacent main block networks are mainly based on fast Ethernet technology . With current research and operational tasks highly dependent on IT infrastructure that is being enabled through NM-Net, the performance of the infrastructure are most critical. This paper will discuss NM-Net implementing gigabit-based networking system and performance network design hierarchy in order to achieve highest availability of inter networking services in the agency thus catalyzing Nuclear Malaysia future research initiative. (author)

The establishment of heterogeneous networks in performative spaces

DEFF Research Database (Denmark)

Suenson, Valinka; Harder, Henrik

2010-01-01

This paper presents an empirical research combining the Actor Network Theory with a development of RFID (Radio Frequency Identification) technology for tracking indoor movement behavior. The aim of the paper is to disucss the value of RFID technology as a method for observing heterogeneous networks...... and architecture through this theoretical perspective, it highlights the importance of the user involvement in the performative spaces where materiality becomes an actant on equal terms with the users. This paper discusses the use of RFID technology for tracking indoor movenment behavior as a method for examining...

IDI diesel engine performance and exhaust emission analysis using biodiesel with an artificial neural network (ANN

Directory of Open Access Journals (Sweden)

K. Prasada Rao

2017-09-01

Full Text Available Biodiesel is receiving increasing attention each passing day because of its fuel properties and compatibility. This study investigates the performance and emission characteristics of single cylinder four stroke indirect diesel injection (IDI engine fueled with Rice Bran Methyl Ester (RBME with Isopropanol additive. The investigation is done through a combination of experimental data analysis and artificial neural network (ANN modeling. The study used IDI engine experimental data to evaluate nine engine performance and emission parameters including Exhaust Gas Temperature (E.G.T, Brake Specific Fuel Consumption (BSFC, Brake Thermal Efficiency (B.The and various emissions like Hydrocarbons (HC, Carbon monoxide (CO, Carbon dioxide (CO2, Oxygen (O2, Nitrogen oxides (NOX and smoke. For the ANN modeling standard back propagation algorithm was found to be the optimum choice for training the model. A multi-layer perception (MLP network was used for non-linear mapping between the input and output parameters. It was found that ANN was able to predict the engine performance and exhaust emissions with a correlation coefficient of 0.995, 0.980, 0.999, 0.985, 0.999, 0.999, 0.980, 0.999, and 0.999 for E.G.T, BSFC, B.The, HC, O2, CO2, CO, NOX, smoke respectively.

Enhanced memory performance thanks to neural network assortativity

International Nuclear Information System (INIS)

Franciscis, S. de; Johnson, S.; Torres, J. J.

2011-01-01

The behaviour of many complex dynamical systems has been found to depend crucially on the structure of the underlying networks of interactions. An intriguing feature of empirical networks is their assortativity--i.e., the extent to which the degrees of neighbouring nodes are correlated. However, until very recently it was difficult to take this property into account analytically, most work being exclusively numerical. We get round this problem by considering ensembles of equally correlated graphs and apply this novel technique to the case of attractor neural networks. Assortativity turns out to be a key feature for memory performance in these systems - so much so that for sufficiently correlated topologies the critical temperature diverges. We predict that artificial and biological neural systems could significantly enhance their robustness to noise by developing positive correlations.

A visual analytics system for optimizing the performance of large-scale networks in supercomputing systems

Directory of Open Access Journals (Sweden)

Takanori Fujiwara

2018-03-01

Full Text Available The overall efficiency of an extreme-scale supercomputer largely relies on the performance of its network interconnects. Several of the state of the art supercomputers use networks based on the increasingly popular Dragonfly topology. It is crucial to study the behavior and performance of different parallel applications running on Dragonfly networks in order to make optimal system configurations and design choices, such as job scheduling and routing strategies. However, in order to study these temporal network behavior, we would need a tool to analyze and correlate numerous sets of multivariate time-series data collected from the Dragonfly’s multi-level hierarchies. This paper presents such a tool–a visual analytics system–that uses the Dragonfly network to investigate the temporal behavior and optimize the communication performance of a supercomputer. We coupled interactive visualization with time-series analysis methods to help reveal hidden patterns in the network behavior with respect to different parallel applications and system configurations. Our system also provides multiple coordinated views for connecting behaviors observed at different levels of the network hierarchies, which effectively helps visual analysis tasks. We demonstrate the effectiveness of the system with a set of case studies. Our system and findings can not only help improve the communication performance of supercomputing applications, but also the network performance of next-generation supercomputers. Keywords: Supercomputing, Parallel communication network, Dragonfly networks, Time-series data, Performance analysis, Visual analytics

Performance modeling, loss networks, and statistical multiplexing

CERN Document Server

Mazumdar, Ravi

2009-01-01

This monograph presents a concise mathematical approach for modeling and analyzing the performance of communication networks with the aim of understanding the phenomenon of statistical multiplexing. The novelty of the monograph is the fresh approach and insights provided by a sample-path methodology for queueing models that highlights the important ideas of Palm distributions associated with traffic models and their role in performance measures. Also presented are recent ideas of large buffer, and many sources asymptotics that play an important role in understanding statistical multiplexing. I

The Global Seismographic Network (GSN): Deployment of Next Generation VBB Borehole Sensors and Improving Overall Network Noise Performance

Science.gov (United States)

Hafner, K.; Davis, P.; Wilson, D.; Sumy, D.

2017-12-01

The Global Seismographic Network (GSN) recently received delivery of the next generation Very Broadband (VBB) borehole sensors purchased through funding from the DOE. Deployment of these sensors will be underway during the end of summer and fall of 2017 and they will eventually replace the aging KS54000 sensors at approximately one-third of the GSN network stations. We will present the latest methods of deploying these sensors in the existing deep boreholes. To achieve lower noise performance at some sites, emplacement in shallow boreholes might result in lower noise performance for the existing site conditions. In some cases shallow borehole installations may be adapted to vault stations (which make up two thirds of the network), as a means of reducing tilt-induced signals on the horizontal components. The GSN is creating a prioritized list of equipment upgrades at selected stations with the ultimate goal of optimizing overall network data availability and noise performance. For an overview of the performance of the current GSN relative to selected set of metrics, we are utilizing data quality metrics and Probability Density Functions (PDFs)) generated by the IRIS Data Management Centers' (DMC) MUSTANG (Modular Utility for Statistical Knowledge Gathering) and LASSO (Latest Assessment of Seismic Station Observations) tools. We will present our metric analysis of GSN performance in 2016, and show the improvements at GSN sites resulting from recent instrumentation and infrastructure upgrades.

Energetic Performance of Service-oriented Multi-radio Networks: Issues and Perspectives

OpenAIRE

Caporuscio , Mauro; Charlet , Damien; Issarny , Valérie; Navarra , Alfredo

2006-01-01

Wireless devices now hold multiple radio interfaces, allowing to switch from one network to another according to required connectivity and related quality. Still, the selection of the best radio interface for a specific connection is under the responsibility of the end-user in most cases. Integrated multi-radio network management so as to improve the overall performance of the network(s) has led to a number of research efforts over the last few years. However, several challenges remain due to...

Performance Analysis of RF-FSO Multi-Hop Networks

KAUST Repository

Makki, Behrooz; Svensson, Tommy; Brandt-Pearce, Maite; Alouini, Mohamed-Slim

2017-01-01

We study the performance of multi-hop networks composed of millimeter wave (MMW)-based radio frequency (RF) and free-space optical (FSO) links. The results are obtained in the cases with and without hybrid automatic repeat request (HARQ). Taking

Individual, contextual and network characteristics of blood donors and non-donors: a systematic review of recent literature

Science.gov (United States)

Piersma, Tjeerd W.; Bekkers, René; Klinkenberg, Elisabeth F.; de Kort, Wim L.A.M.; Merz, Eva-Maria

2017-01-01

Background The ageing population and recent migration flows may negatively affect the blood supply in the long term, increasing the importance of targeted recruitment and retention strategies to address donors. This review sought to identify individual, network and contextual characteristics related to blood donor status and behaviour, to systematically discuss differences between study results, and to identify possible factors to target in recruitment and retention efforts. Methods The systematic review was conducted in accordance with a predefined PROSPERO protocol (CRD42016039591). After quality assessments by multiple independent raters, a final set of 66 peer-reviewed papers, published between October 2009 and January 2017, were included for review. Results Individual and contextual characteristics of blood donor status and behaviour were categorised into five main lines of research: donor demographics, motivations and barriers, adverse reactions and deferral, contextual factors, and blood centre factors. Results on donor demographics, motivations and barriers, and contextual factors were inconclusive, differing between studies, countries, and sample characteristics. Adverse reactions and deferral were negatively related to blood donor behaviour. Blood centre factors play an important role in donor management, e.g., providing information, reminders, and (non-)monetary rewards. No studies were found on network characteristics of (non-)donors. Discussion Although individual and contextual characteristics strongly relate to blood donor status and behaviour, mechanisms underlying these relations have not been studied sufficiently. We want to stress the importance of longitudinal studies in donor behaviour, exploring the role of life events and network characteristics within blood donor careers. Increased understanding of donor behaviour will assist policy makers of blood collection agencies, with the ultimate goal of safeguarding a sufficient and matching blood

Individual, contextual and network characteristics of blood donors and non-donors: a systematic review of recent literature.

Science.gov (United States)

Piersma, Tjeerd W; Bekkers, René; Klinkenberg, Elisabeth F; De Kort, Wim L A M; Merz, Eva-Maria

2017-09-01

The ageing population and recent migration flows may negatively affect the blood supply in the long term, increasing the importance of targeted recruitment and retention strategies to address donors. This review sought to identify individual, network and contextual characteristics related to blood donor status and behaviour, to systematically discuss differences between study results, and to identify possible factors to target in recruitment and retention efforts. The systematic review was conducted in accordance with a predefined PROSPERO protocol (CRD42016039591). After quality assessments by multiple independent raters, a final set of 66 peer-reviewed papers, published between October 2009 and January 2017, were included for review. Individual and contextual characteristics of blood donor status and behaviour were categorised into five main lines of research: donor demographics, motivations and barriers, adverse reactions and deferral, contextual factors, and blood centre factors. Results on donor demographics, motivations and barriers, and contextual factors were inconclusive, differing between studies, countries, and sample characteristics. Adverse reactions and deferral were negatively related to blood donor behaviour. Blood centre factors play an important role in donor management, e.g., providing information, reminders, and (non-)monetary rewards. No studies were found on network characteristics of (non-)donors. Although individual and contextual characteristics strongly relate to blood donor status and behaviour, mechanisms underlying these relations have not been studied sufficiently. We want to stress the importance of longitudinal studies in donor behaviour, exploring the role of life events and network characteristics within blood donor careers. Increased understanding of donor behaviour will assist policy makers of blood collection agencies, with the ultimate goal of safeguarding a sufficient and matching blood supply.

Performance Analysis of Receive Diversity in Wireless Sensor Networks over GBSBE Models

Science.gov (United States)

Goel, Shivali; Abawajy, Jemal H.; Kim, Tai-hoon

2010-01-01

Wireless sensor networks have attracted a lot of attention recently. In this paper, we develop a channel model based on the elliptical model for multipath components involving randomly placed scatterers in the scattering region with sensors deployed on a field. We verify that in a sensor network, the use of receive diversity techniques improves the performance of the system. Extensive performance analysis of the system is carried out for both single and multiple antennas with the applied receive diversity techniques. Performance analyses based on variations in receiver height, maximum multipath delay and transmit power have been performed considering different numbers of antenna elements present in the receiver array, Our results show that increasing the number of antenna elements for a wireless sensor network does indeed improve the BER rates that can be obtained. PMID:22163510

Statistical performance evaluation of ECG transmission using wireless networks.

Science.gov (United States)

Shakhatreh, Walid; Gharaibeh, Khaled; Al-Zaben, Awad

2013-07-01

This paper presents simulation of the transmission of biomedical signals (using ECG signal as an example) over wireless networks. Investigation of the effect of channel impairments including SNR, pathloss exponent, path delay and network impairments such as packet loss probability; on the diagnosability of the received ECG signal are presented. The ECG signal is transmitted through a wireless network system composed of two communication protocols; an 802.15.4- ZigBee protocol and an 802.11b protocol. The performance of the transmission is evaluated using higher order statistics parameters such as kurtosis and Negative Entropy in addition to the common techniques such as the PRD, RMS and Cross Correlation.

The Influence of Top Management Team Characteristics on BPD Performance

Directory of Open Access Journals (Sweden)

Joy Elly Tulung

2015-12-01

Full Text Available Based on ”upper echelons theory”, this paper investigates the relation between top management team composition and BPD performance. For top management team characteristics, we employ age, level of education, background of education, gender, and functional background, while for measured the BPD performance we employ return on asset (ROA, return on equity (ROE, capital adequacy ratio (CAR, net interest margin (NIM, loan to deposit ratio (LDR, non-performing loan (NPL and operation expenses to operation income (BOPO. The results show that all characteristics have positive significant influences on BPD performance.

Subjective Evaluation of Packet Service Performance in UMTS and Heterogeneous Networks

DEFF Research Database (Denmark)

Teyeb, Oumer Mohammed; Sørensen, Troels Bundgaard; Mogensen, Preben

2006-01-01

Quality of Service (QoS) in mobile telecommunication systems is usually identified by some basic performance metrics such as delay, throughput and jitter. However, the main impact of service quality is on the end user, and as such a detailed study of service performance should involve the end user......, users rated the perceived quality of the services under different network conditions. The users’ ratings are analyzed and the results showed clear trends with very few outliers. The objective and subjective measures also were found to be in line except for one case where a higher layer effect influenced....... In this paper, such an approach is taken where subjective performance evaluation is undertaken for web browsing and video streaming services in Universal Mobile Telecommunication System (UMTS) and a heterogeneous network comprised of UMTS and Wireless LAN (WLAN). Using a real-time network emulation testbed...

Performance and Complexity of Tunable Sparse Network Coding with Gradual Growing Tuning Functions over Wireless Networks

DEFF Research Database (Denmark)

Garrido, Pablo; Sørensen, Chres Wiant; Roetter, Daniel Enrique Lucani

2016-01-01

Random Linear Network Coding (RLNC) has been shown to be a technique with several benefits, in particular when applied over wireless mesh networks, since it provides robustness against packet losses. On the other hand, Tunable Sparse Network Coding (TSNC) is a promising concept, which leverages...... a trade-off between computational complexity and goodput. An optimal density tuning function has not been found yet, due to the lack of a closed-form expression that links density, performance and computational cost. In addition, it would be difficult to implement, due to the feedback delay. In this work...

NETWORK RELATIONSHIPS IN SMALL INCUBATED TECHNOLOGY-BASED (ITBS FIRMS: A STUDY OF ITS IMPORTANCE TO ORGANIZATIONAL PERFORMANCE IN THE PERCEPTION OF ENTREPRENEURS

Directory of Open Access Journals (Sweden)

Alessandra Vasconcelos Gallon

2010-01-01

Full Text Available The objective of this article is to describe the network of relationships and identify the importance of these relationships to the organizational performance of small ITBs incubated in the perception of entrepreneurs. Therefore, the research was exploratory, with qualitative method in the first part and descriptive, using a quantitative method in the continuation. Data were collected through a script with open questions and two structured questionnaires. The manager of the incubator and entrepreneurs from 14 residents were ITBs social subjects respondents. Component analysis of the relationship network of ITBs was to: (i examine the characteristics of the network of relationships of ITBs incubated by a statement of means-ends relationships, related by links of influence, and (ii note that there are line between efforts to meet the goals set by both ITBs incubated, as the incubator, and the importance of achieving these objectives for the improvement of organizational performance of ITBs.

NETWORK RELATIONSHIPS IN SMALL INCUBATED TECHNOLOGY-BASED (ITBS FIRMS: A STUDY OF ITS IMPORTANCE TO ORGANIZATIONAL PERFORMANCE IN THE PERCEPTION OF ENTREPRENEURS

Directory of Open Access Journals (Sweden)

Alessandra Vasconcelos Gallon

2009-12-01

Full Text Available The objective of this article is to describe the network of relationships and identify the importance of these relationships to the organizational performance of small ITBs incubated in the perception of entrepreneurs. Therefore, the research was exploratory, with qualitative method in the first part and descriptive, using a quantitative method in the continuation. Data were collected through a script with open questions and two structured questionnaires. The manager of the incubator and entrepreneurs from 14 residents were ITBs social subjects respondents. Component analysis of the relationship network of ITBs was to: (i examine the characteristics of the network of relationships of ITBs incubated by a statement of means-ends relationships,related by links of influence, and (ii note that there are line between efforts to meet the goals set by both ITBs incubated, as the incubator, and the importance of achieving these objectives for the improvement of organizational performance of ITBs.

Investigating And Evaluating Of Network Failures And Performance Over Distributed WAN In Application Protocol Layer

Directory of Open Access Journals (Sweden)

Enoch Okoh Kofi

2015-08-01

Full Text Available The Experiment was done to find out network failures and application performance relationship over distributed Wide Area Net WAN. In order to access related application over the cloud there must be an internet connectivity which will help the respective workstations to access the remote server for applications being deployed over the network. Bandwidth improvement helps in reducing utilization over the network and it also helps in improving Application Efficiency of these Applications in terms of Response Time. Routers were configured under Enhance Interior Gateway Routing Protocol EIGRP to reduce utilization and to ensure load sharing over the network. Three scenarios were modeled and their performance efficiency was evaluated. A modeled computer Network with and without a fail Router under different scenarios and such Network was simulated with emphasis on the Application Performance. The Experiment was done for fifty workstations under three scenarios and these three scenarios were accessed and evaluated on experimental basis using Riverbed modeler to show the Effect of Application Network performance. The performance results show that increasing the bandwidth reduces utilization and also with the failure of one communication bandwidth users can still access Network Application with a minimal cost.

Research about reactor operator's personability characteristics and performance

Energy Technology Data Exchange (ETDEWEB)

Wei Li; He Xuhong; Zhao Bingquan [Tsinghua Univ., Institute of Nuclear Energy Technology, Beijing (China)

2003-03-01

To predict and evaluate the reactor operator's performance by personality characteristics is an important part of reactor operator safety assessment. Using related psychological theory combined with the Chinese operator's fact and considering the effect of environmental factors to personality analysis, paper does the research about the about the relationships between reactor operator's performance and personality characteristics, and offers the reference for operator's selection, using and performance in the future. (author)

OPTIMAL CONFIGURATION OF A COMMAND AND CONTROL NETWORK: BALANCING PERFORMANCE AND RECONFIGURATION CONSTRAINTS

Energy Technology Data Exchange (ETDEWEB)

L. DOWELL

1999-08-01

The optimization of the configuration of communications and control networks is important for assuring the reliability and performance of the networks. This paper presents techniques for determining the optimal configuration for such a network in the presence of communication and connectivity constraints. reconfiguration to restore connectivity to a data-fusion network following the failure of a network component.

Relationship Between Job Characteristics And Job Performance Of ...

African Journals Online (AJOL)

The agricultural extension agent is a key stakeholder in extension systems. The nature of their work is so important that it has overriding effect on their job performance. This study investigates the relationship between job characteristics and job performance of agricultural extension agents in Imo and Rivers States, Nigeria.

Performance Analysis of Cluster Formation in Wireless Sensor Networks.

Science.gov (United States)

Montiel, Edgar Romo; Rivero-Angeles, Mario E; Rubino, Gerardo; Molina-Lozano, Heron; Menchaca-Mendez, Rolando; Menchaca-Mendez, Ricardo

2017-12-13

Clustered-based wireless sensor networks have been extensively used in the literature in order to achieve considerable energy consumption reductions. However, two aspects of such systems have been largely overlooked. Namely, the transmission probability used during the cluster formation phase and the way in which cluster heads are selected. Both of these issues have an important impact on the performance of the system. For the former, it is common to consider that sensor nodes in a clustered-based Wireless Sensor Network (WSN) use a fixed transmission probability to send control data in order to build the clusters. However, due to the highly variable conditions experienced by these networks, a fixed transmission probability may lead to extra energy consumption. In view of this, three different transmission probability strategies are studied: optimal, fixed and adaptive. In this context, we also investigate cluster head selection schemes, specifically, we consider two intelligent schemes based on the fuzzy C-means and k-medoids algorithms and a random selection with no intelligence. We show that the use of intelligent schemes greatly improves the performance of the system, but their use entails higher complexity and selection delay. The main performance metrics considered in this work are energy consumption, successful transmission probability and cluster formation latency. As an additional feature of this work, we study the effect of errors in the wireless channel and the impact on the performance of the system under the different transmission probability schemes.

Performance Analysis of Cluster Formation in Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Edgar Romo Montiel

2017-12-01

Full Text Available Clustered-based wireless sensor networks have been extensively used in the literature in order to achieve considerable energy consumption reductions. However, two aspects of such systems have been largely overlooked. Namely, the transmission probability used during the cluster formation phase and the way in which cluster heads are selected. Both of these issues have an important impact on the performance of the system. For the former, it is common to consider that sensor nodes in a clustered-based Wireless Sensor Network (WSN use a fixed transmission probability to send control data in order to build the clusters. However, due to the highly variable conditions experienced by these networks, a fixed transmission probability may lead to extra energy consumption. In view of this, three different transmission probability strategies are studied: optimal, fixed and adaptive. In this context, we also investigate cluster head selection schemes, specifically, we consider two intelligent schemes based on the fuzzy C-means and k-medoids algorithms and a random selection with no intelligence. We show that the use of intelligent schemes greatly improves the performance of the system, but their use entails higher complexity and selection delay. The main performance metrics considered in this work are energy consumption, successful transmission probability and cluster formation latency. As an additional feature of this work, we study the effect of errors in the wireless channel and the impact on the performance of the system under the different transmission probability schemes.

Vibrational characteristics of graphene sheets elucidated using an elastic network model.

Science.gov (United States)

Kim, Min Hyeok; Kim, Daejoong; Choi, Jae Boong; Kim, Moon Ki

2014-08-07

Recent studies of graphene have demonstrated its great potential for highly sensitive resonators. In order to capture the intrinsic vibrational characteristics of graphene, we propose an atomistic modeling method called the elastic network model (ENM), in which a graphene sheet is modeled as a mass-spring network of adjacent atoms connected by various linear springs with specific bond ratios. Normal mode analysis (NMA) reveals the various vibrational features of bi-layer graphene sheets (BLGSs) clamped at two edges. We also propose a coarse-graining (CG) method to extend our graphene study into the meso- and macroscales, at which experimental measurements and synthesis of graphene become practical. The simulation results show good agreement with experimental observations. Therefore, the proposed ENM approach will not only shed light on the theoretical study of graphene mechanics, but also play an important role in the design of highly-sensitive graphene-based resonators.

Social-aware data dissemination in opportunistic mobile social networks

Science.gov (United States)

Yang, Yibo; Zhao, Honglin; Ma, Jinlong; Han, Xiaowei

Opportunistic Mobile Social Networks (OMSNs), formed by mobile users with social relationships and characteristics, enhance spontaneous communication among users that opportunistically encounter each other. Such networks can be exploited to improve the performance of data forwarding. Discovering optimal relay nodes is one of the important issues for efficient data propagation in OMSNs. Although traditional centrality definitions to identify the nodes features in network, they cannot identify effectively the influential nodes for data dissemination in OMSNs. Existing protocols take advantage of spatial contact frequency and social characteristics to enhance transmission performance. However, existing protocols have not fully exploited the benefits of the relations and the effects between geographical information, social features and user interests. In this paper, we first evaluate these three characteristics of users and design a routing protocol called Geo-Social-Interest (GSI) protocol to select optimal relay nodes. We compare the performance of GSI using real INFOCOM06 data sets. The experiment results demonstrate that GSI overperforms the other protocols with highest data delivery ratio and low communication overhead.

Value networks in manufacturing sustainability and performance excellence

CERN Document Server

Uusitalo, Teuvo

2017-01-01

This book highlights innovative solutions together with various techniques and methods that can help support the manufacturing sector to excel in economic, social, and environmental terms in networked business environments. The book also furthers understanding of sustainable manufacturing from the perspective of value creation in manufacturing networks, by capitalizing on the outcomes of the European ‘Sustainable Value Creation in Manufacturing Networks’ project. New dynamics and uncertainties in modern markets call for innovative solutions in the global manufacturing sector. While the manufacturing sector is traditionally driven by technology, it also requires other managerial and organizational solutions in terms of network governance, business models, sustainable solution development for products and services, performance management portals, etc., which can provide major competitive advantages for companies. At the same time, the manufacturing industry is subject to a change process, where business net...

Network Performance Evaluation of Abis Interface over DVB-S2 in the GSM over Satellite Network

Directory of Open Access Journals (Sweden)

S. B. Musabekov

2010-01-01

Full Text Available This paper deals with establishing a GSM link over Satellite. Abis interface, which is defined between Base Transceiver Station (BTS and Base Station Controller (BSC, in a GSM network is considered here to be routed over the Satellite. The satellite link enables a quick and cost-effective GSM link in meagerly populated areas. A different scenario comparison was done to understand the impact of Satellite environment on network availability comparing to terrestrial scenario. We have implemented an Abis interface over DVB S2 in NS2 and evaluated the performance over the high delay and loss satellite channel. Network performance was evaluated with respect to Satellite channel delay and DVB S2 encapsulation efficiency under different amount of user traffic and compared with the terrestrial scenario. The results clearly showed an increased amount of SDCCH and TCH channels required in the case of satellite scenario for the same amount of traffic in comparison to conventional terrestrial scenario. We have optimized the parameters based on the simulation results. Link budget estimation considering DVB-S2 platform was done to find satellite bandwidth and cost requirements for different network setups.

Performance Analysis of Receive Diversity in Wireless Sensor Networks over GBSBE Models

Directory of Open Access Journals (Sweden)

Tai-hoon Kim

2010-12-01

Full Text Available Wireless sensor networks have attracted a lot of attention recently. In this paper, we develop a channel model based on the elliptical model for multipath components involving randomly placed scatterers in the scattering region with sensors deployed on a field. We verify that in a sensor network, the use of receive diversity techniques improves the performance of the system. Extensive performance analysis of the system is carried out for both single and multiple antennas with the applied receive diversity techniques. Performance analyses based on variations in receiver height, maximum multipath delay and transmit power have been performed considering different numbers of antenna elements present in the receiver array, Our results show that increasing the number of antenna elements for a wireless sensor network does indeed improve the BER rates that can be obtained.

Factors Influencing the Performance of German Food SME Formal Networks

Directory of Open Access Journals (Sweden)

Jivka Deiters

2014-08-01

Full Text Available The food sector in Europe can be characterized as a complex, global and dynamically changing network of trade streams, food supply network relations and related product flows which offers a big spectrum for economic output and employment. Innovation is important for the competitiveness of the food industry that is to a large extent comprised of small and medium sized enterprises (SMEs. For them, innovation has grown extremely subordinate to interaction in networks. Network initiatives that could provide appropriate support involve social interaction and knowledge exchange, learning and competence development, and coordination (organization and management ofimplementation. This paper is designed to assess the factors that affect the performance of German food SME formal networks. It also addresses the consequences at the network and macro level. The analysis was explored by using the laddering technique based on the means‐end chain theory. The findings will help to build up a “network learning toolbox” that is adapted to the particular requirements of the different target groups such as of SMEs, network managers and policy makers. The “network learning toolbox” should improve network learning, which is adriver for improvements in innovation, economic growth and sustainable competitive advantage for food SMEs.

From Network to Research – Ten Years of Music Informatics, Performance and Aesthetics

DEFF Research Database (Denmark)

Frimodt-Møller, Søren R.; Grund, Cynthia M.; Jensen, Kristoffer

2011-01-01

This article briefly chronicles the history of the Nordic Network of Music Informatics, Performance and Aesthetics (NNIMIPA) and its roots in previous research networks and milieus. It explains how a cross-disciplinary network works and gives rise to research projects that bridge the gap between...... the disciplines involved. As examples, three thematically linked projects within NNIMIPA are presented. These projects all have performance interaction (between musicians and between musician and audience) as their nexus....

PERFORMANCE EVALUATION OF VARIANCES IN BACKPROPAGATION NEURAL NETWORK USED FOR HANDWRITTEN CHARACTER RECOGNITION

OpenAIRE

Vairaprakash Gurusamy *1 & K.Nandhini2

2017-01-01

A Neural Network is a powerful data modeling tool that is able to capture and represent complex input/output relationships. The motivation for the development of neural network technology stemmed from the desire to develop an artificial system that could perform "intelligent" tasks similar to those performed by the human brain.Back propagation was created by generalizing the Widrow-Hoff learning rule to multiple-layer networks and nonlinear differentiable transfer functions. The term back pro...

Externally induced frontoparietal synchronization modulates network dynamics and enhances working memory performance.

Science.gov (United States)

Violante, Ines R; Li, Lucia M; Carmichael, David W; Lorenz, Romy; Leech, Robert; Hampshire, Adam; Rothwell, John C; Sharp, David J

2017-03-14

Cognitive functions such as working memory (WM) are emergent properties of large-scale network interactions. Synchronisation of oscillatory activity might contribute to WM by enabling the coordination of long-range processes. However, causal evidence for the way oscillatory activity shapes network dynamics and behavior in humans is limited. Here we applied transcranial alternating current stimulation (tACS) to exogenously modulate oscillatory activity in a right frontoparietal network that supports WM. Externally induced synchronization improved performance when cognitive demands were high. Simultaneously collected fMRI data reveals tACS effects dependent on the relative phase of the stimulation and the internal cognitive processing state. Specifically, synchronous tACS during the verbal WM task increased parietal activity, which correlated with behavioral performance. Furthermore, functional connectivity results indicate that the relative phase of frontoparietal stimulation influences information flow within the WM network. Overall, our findings demonstrate a link between behavioral performance in a demanding WM task and large-scale brain synchronization.

A network application for modeling a centrifugal compressor performance map

Science.gov (United States)

Nikiforov, A.; Popova, D.; Soldatova, K.

2017-08-01

The approximation of aerodynamic performance of a centrifugal compressor stage and vaneless diffuser by neural networks is presented. Advantages, difficulties and specific features of the method are described. An example of a neural network and its structure is shown. The performances in terms of efficiency, pressure ratio and work coefficient of 39 model stages within the range of flow coefficient from 0.01 to 0.08 were modeled with mean squared error 1.5 %. In addition, the loss and friction coefficients of vaneless diffusers of relative widths 0.014-0.10 are modeled with mean squared error 2.45 %.

A New Processing Method Combined with BP Neural Network for Francis Turbine Synthetic Characteristic Curve Research

Directory of Open Access Journals (Sweden)

Junyi Li

2017-01-01

Full Text Available A BP (backpropagation neural network method is employed to solve the problems existing in the synthetic characteristic curve processing of hydroturbine at present that most studies are only concerned with data in the high efficiency and large guide vane opening area, which can hardly meet the research requirements of transition process especially in large fluctuation situation. The principle of the proposed method is to convert the nonlinear characteristics of turbine to torque and flow characteristics, which can be used for real-time simulation directly based on neural network. Results show that obtained sample data can be extended successfully to cover working areas wider under different operation conditions. Another major contribution of this paper is the resampling technique proposed in the paper to overcome the limitation to sample period simulation. In addition, a detailed analysis for improvements of iteration convergence of the pressure loop is proposed, leading to a better iterative convergence during the head pressure calculation. Actual applications verify that methods proposed in this paper have better simulation results which are closer to the field and provide a new perspective for hydroturbine synthetic characteristic curve fitting and modeling.

Ensemble of classifiers based network intrusion detection system performance bound

CSIR Research Space (South Africa)

Mkuzangwe, Nenekazi NP

2017-11-01

Full Text Available This paper provides a performance bound of a network intrusion detection system (NIDS) that uses an ensemble of classifiers. Currently researchers rely on implementing the ensemble of classifiers based NIDS before they can determine the performance...

Performance Analysis of TDMA Protocol in a Femtocell Network

Directory of Open Access Journals (Sweden)

Wanod Kumar

2014-07-01

Full Text Available In this paper, we evaluate the performance of TDMA (Time Division Multiple Access protocol using queuing theory in a femtocell network. The fair use of wireless channel among the users of network is carried out using TDMA protocol. The arrival of data packets from M communicating nodes becomes multiple Poisson process. The time slots of TDMA protocol represent c servers to communicate data packets coming from communicating nodes to the input of FAP (Femtocell Access Point. The service time of each server (time slot is exponentially distributed. This complete communication scenario using TDMA protocol is modeled using M/M/c queue. The performance of the protocol is evaluated in terms of mean number in system, average system delay and utilization for varying traffic intensity

Rumor diffusion in heterogeneous networks by considering the individuals' subjective judgment and diverse characteristics

Science.gov (United States)

Ma, Jing; Zhu, He

2018-06-01

In this study, we propose a novel rumor spreading model in consideration of the individuals' subjective judgment and diverse characteristics. To reflect the diversity of the individuals' characteristics, we introduce two probability distribution functions, which could be chosen arbitrarily or given by empirical data, to characterize individuals' mastering degree of knowledge with respect to the domain of a specific rumor and individuals' rationality degree. Different from existing models, no two persons in our model are identical, and each individual can judge the authenticity of the information, e.g., rumors, with his distinctive characteristics. In addition, by means of the mean-field method, we establish the expression of the dynamics of the rumor propagation in the complex heterogeneous networks and derive the rumor spreading threshold. Through the theoretical analysis, we find that the threshold is independent of the forms of the two introduced functions. Furthermore, we prove the stability of the rumor-free equilibrium set E0. That is if and only if R0 series of numerical simulations to verify the theoretical results and comprehensively illustrate the evolution of the model. The simulation results show that because of the diversity of individuals' characteristics, it becomes more difficult for the rumor to disseminate in the networks and the higher the mean of knowledge and the mean of rationality are, the more time it will take for the model to evolve to the steady state.

Consensus group sessions are useful to reconcile stakeholders’ perspectives about network performance evaluation

Directory of Open Access Journals (Sweden)

Marie-Eve Lamontagne

2010-12-01

Full Text Available Background: Having a common vision among network stakeholders is an important ingredient to developing a performance evaluation process. Consensus methods may be a viable means to reconcile the perceptions of different stakeholders about the dimensions to include in a performance evaluation framework.Objectives: To determine whether individual organizations within traumatic brain injury (TBI networks differ in perceptions about the importance of performance dimensions for the evaluation of TBI networks and to explore the extent to which group consensus sessions could reconcile these perceptions.Methods: We used TRIAGE, a consensus technique that combines an individual and a group data collection phase to explore the perceptions of network stakeholders and to reach a consensus within structured group discussions.Results: One hundred and thirty-nine professionals from 43 organizations within eight TBI networks participated in the individual data collection; 62 professionals from these same organisations contributed to the group data collection. The extent of consensus based on questionnaire results (e.g. individual data collection was low, however, 100% agreement was obtained for each network during the consensus group sessions. The median importance scores and mean ranks attributed to the dimensions by individuals compared to groups did not differ greatly. Group discussions were found useful in understanding the reasons motivating the scoring, for resolving differences among participants, and for harmonizing their values.Conclusion: Group discussions, as part of a consensus technique, appear to be a useful process to reconcile diverging perceptions of network performance among stakeholders.

On the estimation variance for the specific Euler-Poincaré characteristic of random networks.

Science.gov (United States)

Tscheschel, A; Stoyan, D

2003-07-01

The specific Euler number is an important topological characteristic in many applications. It is considered here for the case of random networks, which may appear in microscopy either as primary objects of investigation or as secondary objects describing in an approximate way other structures such as, for example, porous media. For random networks there is a simple and natural estimator of the specific Euler number. For its estimation variance, a simple Poisson approximation is given. It is based on the general exact formula for the estimation variance. In two examples of quite different nature and topology application of the formulas is demonstrated.

Function-Oriented Networking and On-Demand Routing System in Network Using Ant Colony Optimization Algorithm

Directory of Open Access Journals (Sweden)

Young-Bo Sim

2017-11-01

Full Text Available In this paper, we proposed and developed Function-Oriented Networking (FON, a platform for network users. It has a different philosophy as opposed to technologies for network managers of Software-Defined Networking technology, OpenFlow. It is a technology that can immediately reflect the demands of the network users in the network, unlike the existing OpenFlow and Network Functions Virtualization (NFV, which do not reflect directly the needs of the network users. It allows the network user to determine the policy of the direct network, so it can be applied more precisely than the policy applied by the network manager. This is expected to increase the satisfaction of the service users when the network users try to provide new services. We developed FON function that performs on-demand routing for Low-Delay Required service. We analyzed the characteristics of the Ant Colony Optimization (ACO algorithm and found that the algorithm is suitable for low-delay required services. It was also the first in the world to implement the routing software using ACO Algorithm in the real Ethernet network. In order to improve the routing performance, several algorithms of the ACO Algorithm have been developed to enable faster path search-routing and path recovery. The relationship between the network performance index and the ACO routing parameters is derived, and the results are compared and analyzed. Through this, it was possible to develop the ACO algorithm.

Performing particle image velocimetry using artificial neural networks: a proof-of-concept

Science.gov (United States)

Rabault, Jean; Kolaas, Jostein; Jensen, Atle

2017-12-01

Traditional programs based on feature engineering are underperforming on a steadily increasing number of tasks compared with artificial neural networks (ANNs), in particular for image analysis. Image analysis is widely used in fluid mechanics when performing particle image velocimetry (PIV) and particle tracking velocimetry (PTV), and therefore it is natural to test the ability of ANNs to perform such tasks. We report for the first time the use of convolutional neural networks (CNNs) and fully connected neural networks (FCNNs) for performing end-to-end PIV. Realistic synthetic images are used for training the networks and several synthetic test cases are used to assess the quality of each network’s predictions and compare them with state-of-the-art PIV software. In addition, we present tests on real-world data that prove ANNs can be used not only with synthetic images but also with more noisy, imperfect images obtained in a real experimental setup. While the ANNs we present have slightly higher root mean square error than state-of-the-art cross-correlation methods, they perform better near edges and allow for higher spatial resolution than such methods. In addition, it is likely that one could with further work develop ANNs which perform better that the proof-of-concept we offer.

Performance Modeling of Communication Networks with Markov Chains

CERN Document Server

Mo, Jeonghoon

2010-01-01

This book is an introduction to Markov chain modeling with applications to communication networks. It begins with a general introduction to performance modeling in Chapter 1 where we introduce different performance models. We then introduce basic ideas of Markov chain modeling: Markov property, discrete time Markov chain (DTMe and continuous time Markov chain (CTMe. We also discuss how to find the steady state distributions from these Markov chains and how they can be used to compute the system performance metric. The solution methodologies include a balance equation technique, limiting probab

Performance Analysis of Non-saturated IEEE 802.11 DCF Networks

Science.gov (United States)

Zhai, Linbo; Zhang, Xiaomin; Xie, Gang

This letter presents a model with queueing theory to analyze the performance of non-saturated IEEE 802.11 DCF networks. We use the closed queueing network model and derive an approximate representation of throughput which can reveal the relationship between the throughput and the total offered load under finite traffic load conditions. The accuracy of the model is verified by extensive simulations.

Monofractal Characteristics of Traffic in Wireless Sensor Networks for Smart Grid

Directory of Open Access Journals (Sweden)

Ming-Yue Zhai

2014-05-01

Full Text Available Wireless sensor networks (WSNs have extensive applications in the smart grid in recently years. The time series in WSNs in smart grid should be discussed by analysis method which is non-linear. The method of monofractal is used here. Self-similar Hurst parameter calculated by the algorithm of Rescaled Range Analysis (R/S and fractal dimension are obtained, which confirm that the time sequences in WSNs for smart grid belong to the fractal sets and have the characteristic of self- similarity.

Relationships between Isometric Force-Time Characteristics and Dynamic Performance

Directory of Open Access Journals (Sweden)

Thomas Dos’Santos

2017-09-01

Full Text Available The purpose of this study was to explore the relationships between isometric mid-thigh pull (IMTP force-time characteristics (peak force and time-specific force vales (100–250 ms and dynamic performance and compare dynamic performance between stronger and weaker athletes. Forty-three athletes from different sports (rowing, soccer, bicycle motocross, and hockey performed three trials of the squat jump (SJ, countermovement jump (CMJ, and IMTP, and performed a one repetition maximum power clean (PC. Reactive strength index modified (RSImod was also calculated from the CMJ. Statistically significant large correlations between IMTP force-time characteristics and PC (ρ = 0.569–0.674, p < 0.001, and moderate correlations between IMTP force-time characteristics (excluding force at 100 ms and RSImod (ρ = 0.389–0.449, p = 0.013–0.050 were observed. Only force at 250 ms demonstrated a statistically significant moderate correlation with CMJ height (ρ = 0.346, p = 0.016 and no statistically significant associations were observed between IMTP force-time characteristics and SJ height. Stronger athletes (top 10 demonstrated statistically significantly greater CMJ heights, RSImods, and PCs (p ≤ 0.004, g = 1.32–1.89 compared to weaker (bottom 10 athletes, but no differences in SJ height were observed (p = 0.871, g = 0.06. These findings highlight that the ability to apply rapidly high levels of force in short time intervals is integral for PC, CMJ height, and reactive strength.

Changes in brain network efficiency and working memory performance in aging.

Science.gov (United States)

Stanley, Matthew L; Simpson, Sean L; Dagenbach, Dale; Lyday, Robert G; Burdette, Jonathan H; Laurienti, Paul J

2015-01-01

Working memory is a complex psychological construct referring to the temporary storage and active processing of information. We used functional connectivity brain network metrics quantifying local and global efficiency of information transfer for predicting individual variability in working memory performance on an n-back task in both young (n = 14) and older (n = 15) adults. Individual differences in both local and global efficiency during the working memory task were significant predictors of working memory performance in addition to age (and an interaction between age and global efficiency). Decreases in local efficiency during the working memory task were associated with better working memory performance in both age cohorts. In contrast, increases in global efficiency were associated with much better working performance for young participants; however, increases in global efficiency were associated with a slight decrease in working memory performance for older participants. Individual differences in local and global efficiency during resting-state sessions were not significant predictors of working memory performance. Significant group whole-brain functional network decreases in local efficiency also were observed during the working memory task compared to rest, whereas no significant differences were observed in network global efficiency. These results are discussed in relation to recently developed models of age-related differences in working memory.

Visualizing Network Traffic to Understand the Performance of Massively Parallel Simulations

KAUST Repository

Landge, A. G.

2012-12-01

The performance of massively parallel applications is often heavily impacted by the cost of communication among compute nodes. However, determining how to best use the network is a formidable task, made challenging by the ever increasing size and complexity of modern supercomputers. This paper applies visualization techniques to aid parallel application developers in understanding the network activity by enabling a detailed exploration of the flow of packets through the hardware interconnect. In order to visualize this large and complex data, we employ two linked views of the hardware network. The first is a 2D view, that represents the network structure as one of several simplified planar projections. This view is designed to allow a user to easily identify trends and patterns in the network traffic. The second is a 3D view that augments the 2D view by preserving the physical network topology and providing a context that is familiar to the application developers. Using the massively parallel multi-physics code pF3D as a case study, we demonstrate that our tool provides valuable insight that we use to explain and optimize pF3D-s performance on an IBM Blue Gene/P system. © 1995-2012 IEEE.

The company you keep: Effects of leader and teams network position on performance

NARCIS (Netherlands)

Vernet, A; Deichmann, D.; Moser, C.

2016-01-01

In this paper we argue that leaders positively influence team performance through their positions in a collaboration network. We propose also that the leader’s effect on team performance is moderated by the position of the team in the larger collaboration network. We distinguish between brokerage

Social support network characteristics of incarcerated women with co-occurring major depressive and substance use disorders

OpenAIRE

Nargiso, Jessica E.; Kuo, Caroline C.; Zlotnick, Caron; Johnson, Jennifer E.

2014-01-01

The nature of social support available to incarcerated women is not well understood, particularly among women at high risk of negative outcomes, including women dually-diagnosed with Major Depressive Disorder and a Substance Use Disorder (MDD-SUD). Descriptive statistics and paired-tests were conducted on 60 incarcerated MDD-SUD women receiving in-prison substance use and depression treatments to characterize the women’s social networks, including the strength of support, network characterist...

A Public-Private Partnership Improves Clinical Performance In A Hospital Network In Lesotho.

Science.gov (United States)

McIntosh, Nathalie; Grabowski, Aria; Jack, Brian; Nkabane-Nkholongo, Elizabeth Limakatso; Vian, Taryn

2015-06-01

Health care public-private partnerships (PPPs) between a government and the private sector are based on a business model that aims to leverage private-sector expertise to improve clinical performance in hospitals and other health facilities. Although the financial implications of such partnerships have been analyzed, few studies have examined the partnerships' impact on clinical performance outcomes. Using quantitative measures that reflected capacity, utilization, clinical quality, and patient outcomes, we compared a government-managed hospital network in Lesotho, Africa, and the new PPP-managed hospital network that replaced it. In addition, we used key informant interviews to help explain differences in performance. We found that the PPP-managed network delivered more and higher-quality services and achieved significant gains in clinical outcomes, compared to the government-managed network. We conclude that health care public-private partnerships may improve hospital performance in developing countries and that changes in management and leadership practices might account for differences in clinical outcomes. Project HOPE—The People-to-People Health Foundation, Inc.

South African exporter performance: new research into firm-specific and market characteristics

Directory of Open Access Journals (Sweden)

Christopher May

2012-05-01

Full Text Available The export marketing performance of any firm is influenced by a multitude of different factors. Given the multi-faceted nature of the export market, this research study investigated specific factors such as how firm-specific characteristics, product characteristics, market characteristics and export marketing strategies impact on the export marketing performance of South African manufacturing firms. Some of the findings of this research study indicated that firm size, investment commitment and careful planning, as firm-specific characteristics, had a significant influence on export marketing performance. The relationship between export experience and export marketing performance was insignificant. The degree of pricing adaptation and product adaptation had a significant effect on export marketing performance, while this was not the case with respect to the degree of promotion adaptation and distributor support.

High Performance All-solid Supercapacitors Based on the Network of Ultralong Manganese dioxide/Polyaniline Coaxial Nanowires.

Science.gov (United States)

Zhou, Junli; Yu, Lin; Liu, Wei; Zhang, Xiaodan; Mu, Wei; Du, Xu; Zhang, Zhe; Deng, Yulin

2015-12-08

In recent years, thin, lightweight and flexible solid supercapacitors are of considerable interest as energy storage devices. Here we demonstrated all-solid supercapacitors (SSCs) with high electrochemical properties, low self-discharge characteristics based on manganese dioxide/polyaniline (MNW/PANI) coaxial nanowire networks. The synergistic effect of MnO2/PANI plus the unique coaxial nanostructure of the ultralong nanowires with a highly interconnected network effectively enhance the conductivity and capacitive performance of the SSCs device. The MNW/PANI composite with 62.5% MnO2 exhibits an outstanding areal specific capacitance reaching 346 mF/cm(2) at 5 mV s(-1) which is significant higher than most previously reported solid supercapacitors (15.3 mF/cm(2)-109 mF/cm(2)) and is close to the that of the best graphene films solid state supercapacitors (372 mF/cm(2)). In contrast, only 190 mF/cm(2) of areal specific capacitance was obtained for the pure MnO2 NW network. The supercapacitors also exhibited low leakage current as small as 20.1 μA, which demonstrated that the MNW/PANI SSCs have great potential for practical applications.

High Performance All-solid Supercapacitors Based on the Network of Ultralong Manganese dioxide/Polyaniline Coaxial Nanowires

Science.gov (United States)

Zhou, Junli; Yu, Lin; Liu, Wei; Zhang, Xiaodan; Mu, Wei; Du, Xu; Zhang, Zhe; Deng, Yulin

2015-12-01

In recent years, thin, lightweight and flexible solid supercapacitors are of considerable interest as energy storage devices. Here we demonstrated all-solid supercapacitors (SSCs) with high electrochemical properties, low self-discharge characteristics based on manganese dioxide/polyaniline (MNW/PANI) coaxial nanowire networks. The synergistic effect of MnO2/PANI plus the unique coaxial nanostructure of the ultralong nanowires with a highly interconnected network effectively enhance the conductivity and capacitive performance of the SSCs device. The MNW/PANI composite with 62.5% MnO2 exhibits an outstanding areal specific capacitance reaching 346 mF/cm2 at 5 mV s-1 which is significant higher than most previously reported solid supercapacitors (15.3 mF/cm2-109 mF/cm2) and is close to the that of the best graphene films solid state supercapacitors (372 mF/cm2). In contrast, only 190 mF/cm2 of areal specific capacitance was obtained for the pure MnO2 NW network. The supercapacitors also exhibited low leakage current as small as 20.1 μA, which demonstrated that the MNW/PANI SSCs have great potential for practical applications.

Thermic diode performance characteristics and design manual

Science.gov (United States)

Bernard, D. E.; Buckley, S.

1979-01-01

Thermic diode solar panels are a passive method of space and hot water heating using the thermosyphon principle. Simplified methods of sizing and performing economic analyses of solar heating systems had until now been limited to passive systems. A mathematical model of the thermic diode including its high level of stratification has been constructed allowing its performance characteristics to be studied. Further analysis resulted in a thermic diode design manual based on the f-chart method.

Evaluation of the productive performance characteristics of red ...

African Journals Online (AJOL)

Evaluation of the productive performance characteristics of red tilapia ( Oreochromis sp.) injected with shark DNA into skeletal muscles and maintained diets containing different levels of probiotic and amino yeast.

Performance and carcass characteristics of Yankasa ram fed with ...

African Journals Online (AJOL)

Remember me ... and 50% maize and wheat offal mixture, were better when compared to the control (B0) and other test diet in terms of performance and carcass characteristics. ... Key words: Performance, carcass, biscuit waste, Yankasa ram.

A Hybrid Testbed for Performance Evaluation of Large-Scale Datacenter Networks

DEFF Research Database (Denmark)

Pilimon, Artur; Ruepp, Sarah Renée

2018-01-01

Datacenters (DC) as well as their network interconnects are growing in scale and complexity. They are constantly being challenged in terms of energy and resource utilization efficiency, scalability, availability, reliability and performance requirements. Therefore, these resource-intensive enviro......Datacenters (DC) as well as their network interconnects are growing in scale and complexity. They are constantly being challenged in terms of energy and resource utilization efficiency, scalability, availability, reliability and performance requirements. Therefore, these resource......-intensive environments must be properly tested and analyzed in order to make timely upgrades and transformations. However, a limited number of academic institutions and Research and Development companies have access to production scale DC Network (DCN) testing facilities, and resource-limited studies can produce...... misleading or inaccurate results. To address this problem, we introduce an alternative solution, which forms a solid base for a more realistic and comprehensive performance evaluation of different aspects of DCNs. It is based on the System-in-the-loop (SITL) concept, where real commercial DCN equipment...

High-performance, scalable optical network-on-chip architectures

Science.gov (United States)

Tan, Xianfang

The rapid advance of technology enables a large number of processing cores to be integrated into a single chip which is called a Chip Multiprocessor (CMP) or a Multiprocessor System-on-Chip (MPSoC) design. The on-chip interconnection network, which is the communication infrastructure for these processing cores, plays a central role in a many-core system. With the continuously increasing complexity of many-core systems, traditional metallic wired electronic networks-on-chip (NoC) became a bottleneck because of the unbearable latency in data transmission and extremely high energy consumption on chip. Optical networks-on-chip (ONoC) has been proposed as a promising alternative paradigm for electronic NoC with the benefits of optical signaling communication such as extremely high bandwidth, negligible latency, and low power consumption. This dissertation focus on the design of high-performance and scalable ONoC architectures and the contributions are highlighted as follow: 1. A micro-ring resonator (MRR)-based Generic Wavelength-routed Optical Router (GWOR) is proposed. A method for developing any sized GWOR is introduced. GWOR is a scalable non-blocking ONoC architecture with simple structure, low cost and high power efficiency compared to existing ONoC designs. 2. To expand the bandwidth and improve the fault tolerance of the GWOR, a redundant GWOR architecture is designed by cascading different type of GWORs into one network. 3. The redundant GWOR built with MRR-based comb switches is proposed. Comb switches can expand the bandwidth while keep the topology of GWOR unchanged by replacing the general MRRs with comb switches. 4. A butterfly fat tree (BFT)-based hybrid optoelectronic NoC (HONoC) architecture is developed in which GWORs are used for global communication and electronic routers are used for local communication. The proposed HONoC uses less numbers of electronic routers and links than its counterpart of electronic BFT-based NoC. It takes the advantages of

The APS control system network

International Nuclear Information System (INIS)

Sidorowicz, K.V.; McDowell, W.P.

1995-01-01

The APS accelerator control system is a distributed system consisting of operator interfaces, a network, and computer-controlled interfaces to hardware. This implementation of a control system has come to be called the open-quotes Standard Model.close quotes The operator interface is a UNDC-based workstation with an X-windows graphical user interface. The workstation may be located at any point on the facility network and maintain full functionality. The function of the network is to provide a generalized communication path between the host computers, operator workstations, input/output crates, and other hardware that comprise the control system. The crate or input/output controller (IOC) provides direct control and input/output interfaces for each accelerator subsystem. The network is an integral part of all modem control systems and network performance will determine many characteristics of a control system. This paper will describe the overall APS network and examine the APS control system network in detail. Metrics are provided on the performance of the system under various conditions

Throughput performance analysis of multirate, multiclass S-ALOHA OFFH-CDMA packet networks

DEFF Research Database (Denmark)

Raddo, Thiago R.; Sanches, Anderson L.; Borges, Ben Hur V

2015-01-01

In this paper, we propose a new throughput expression for multirate, multiclass slotted-ALOHA optical fast frequency hopping code-division multiple-access (OFFH-CDMA) packet networks considering a Poisson distribution for packet composite arrivals. We analyze the packet throughput performance...... of a three-class OFFH-CDMA network, where multirate transmissions are achieved via manipulation of the user's code parameters. It is shown that users transmitting at low rates interfere considerably in the performance of high rate users. Finally, we perform a validation procedure to demonstrate...

OPTIMAL CONFIGURATION OF A COMMAND AND CONTROL NETWORK: BALANCING PERFORMANCE AND RECONFIGURATION CONSTRAINTS

Energy Technology Data Exchange (ETDEWEB)

L. DOWELL

1999-07-01

The optimization of the configuration of communications and control networks is important for assuring the reliability and performance of the networks. This paper presents techniques for determining the optimal configuration for such a network in the presence of communication and connectivity constraints.

The Impact of Social Networks on Students’ Performance

OpenAIRE

Jusuf Zekiri

2016-01-01

The objective of this study is to determine the impact of using social media and its impact on students’ performance and success. This research tries to identify the relationship between students’ use of social networks and their success in their studies. It tries also to find out whether time spent impacts students’ performance and success. Whether students use social media more for entertainment or for teaching and information sharing purposes. The paper uses a quantitative approach for col...

An Efficient Scheme for Aggregation and Presentation of Network Performance in Distributed Brokering Systems

Directory of Open Access Journals (Sweden)

Gurhan Gunduz

2003-12-01

Full Text Available The Internet is presently being used to support increasingly complex interaction models as a result of more and more applications, services and frameworks becoming network centric. Efficient utilization of network and networkedresources is of paramount importance. Network performance gathering is a precursor to any scheme that seeks to provide adaptive routing capabilities for interactions. In this paper we present a network performance aggregation framework that is extensible and appropriate for distributed messaging systems that span multiple realms, disparate communication protocols and support different applications.

HPNAIDM: The High-Performance Network Anomaly/Intrusion Detection and Mitigation System

Energy Technology Data Exchange (ETDEWEB)

Chen, Yan [Northwesten University

2013-12-05

Identifying traffic anomalies and attacks rapidly and accurately is critical for large network operators. With the rapid growth of network bandwidth, such as the next generation DOE UltraScience Network, and fast emergence of new attacks/virus/worms, existing network intrusion detection systems (IDS) are insufficient because they: • Are mostly host-based and not scalable to high-performance networks; • Are mostly signature-based and unable to adaptively recognize flow-level unknown attacks; • Cannot differentiate malicious events from the unintentional anomalies. To address these challenges, we proposed and developed a new paradigm called high-performance network anomaly/intrustion detection and mitigation (HPNAIDM) system. The new paradigm is significantly different from existing IDSes with the following features (research thrusts). • Online traffic recording and analysis on high-speed networks; • Online adaptive flow-level anomaly/intrusion detection and mitigation; • Integrated approach for false positive reduction. Our research prototype and evaluation demonstrate that the HPNAIDM system is highly effective and economically feasible. Beyond satisfying the pre-set goals, we even exceed that significantly (see more details in the next section). Overall, our project harvested 23 publications (2 book chapters, 6 journal papers and 15 peer-reviewed conference/workshop papers). Besides, we built a website for technique dissemination, which hosts two system prototype release to the research community. We also filed a patent application and developed strong international and domestic collaborations which span both academia and industry.

The Enhancing Impact of Friendship Networks on Sales Managers’ Performance

Directory of Open Access Journals (Sweden)

Danny Pimentel Claro

2013-04-01

Full Text Available This paper examines how relationships with friends moderate the impact of professional networks on sales performance. Based on a sample of 204 sales managers in a professional service company, this study presents evidence that friendship networks amplify the effect of sales forces’ professional networks on new product sales as well as on prospecting and converting new deals. Our results offer important insights into the socio-cognitive perspective of sales management literature and suggest that firms should encourage managers to improve their friendships in order to access valuable information that will enhance customer knowledge and support their sales efforts.

172 Networks, Micro Small Enterprises (MSE'S) and Performance ...

African Journals Online (AJOL)

User

It is no doubt that the role of entrepreneurship in the emerging economies such like Kenya ... understand networking and small business performance as there is no single general ... solution for small firm development (Borg 1991, Donckels and Lambrecht. 1995 ..... Scandinavian Journal of Management , 31 (3/4), 83-99.

Multi-objective optimal power flow for active distribution network considering the stochastic characteristic of photovoltaic

Science.gov (United States)

Zhou, Bao-Rong; Liu, Si-Liang; Zhang, Yong-Jun; Yi, Ying-Qi; Lin, Xiao-Ming

2017-05-01

To mitigate the impact on the distribution networks caused by the stochastic characteristic and high penetration of photovoltaic, a multi-objective optimal power flow model is proposed in this paper. The regulation capability of capacitor, inverter of photovoltaic and energy storage system embedded in active distribution network are considered to minimize the expected value of active power the T loss and probability of voltage violation in this model. Firstly, a probabilistic power flow based on cumulant method is introduced to calculate the value of the objectives. Secondly, NSGA-II algorithm is adopted for optimization to obtain the Pareto optimal solutions. Finally, the best compromise solution can be achieved through fuzzy membership degree method. By the multi-objective optimization calculation of IEEE34-node distribution network, the results show that the model can effectively improve the voltage security and economy of the distribution network on different levels of photovoltaic penetration.

Growth performance, blood parameters and carcass characteristics ...

African Journals Online (AJOL)

This study was carried out with one hundred and twenty (120) day-old marshal chicks to investigate the effect of Maxigrain® enzyme supplementation of corn bran based diets on growth performance, carcass characteristics, haematology and serum biochemistry of broilers in an eight weeks experiment. Four experimental ...

Application and Network-Cognizant Proxies - Final Report

Energy Technology Data Exchange (ETDEWEB)

Antonio Ortega; Daniel C. Lee

2003-03-24

OAK B264 Application and Network-Cognizant Proxies - Final Report. Current networks show increasing heterogeneity both in terms of their bandwidths/delays and the applications they are required to support. This is a trend that is likely to intensify in the future, as real-time services, such as video, become more widely available and networking access over wireless links becomes more widespread. For this reason they propose that application-specific proxies, intermediate network nodes that broker the interactions between server and client, will become an increasingly important network element. These proxies will allow adaptation to changes in network characteristics without requiring a direct intervention of either server or client. Moreover, it will be possible to locate these proxies strategically at those points where a mismatch occurs between subdomains (for example, a proxy could be placed so as to act as a bridge between a reliable network domain and an unreliable one). This design philosophy favors scalability in the sense that the basic network infrastructure can remain unchanged while new functionality can be added to proxies, as required by the applications. While proxies can perform numerous generic functions, such as caching or security, they concentrate here on media-specific, and in particular video-specific, tasks. The goal of this project was to demonstrate that application- and network-specific knowledge at a proxy can improve overall performance especially under changing network conditions. They summarize below the work performed to address these issues. Particular effort was spent in studying caching techniques and on video classification to enable DiffServ delivery. other work included analysis of traffic characteristics, optimized media scheduling, coding techniques based on multiple description coding, and use of proxies to reduce computation costs. This work covered much of what was originally proposed but with a necessarily reduced scope.

Distributed dynamic simulations of networked control and building performance applications.

Science.gov (United States)

Yahiaoui, Azzedine

2018-02-01

The use of computer-based automation and control systems for smart sustainable buildings, often so-called Automated Buildings (ABs), has become an effective way to automatically control, optimize, and supervise a wide range of building performance applications over a network while achieving the minimum energy consumption possible, and in doing so generally refers to Building Automation and Control Systems (BACS) architecture. Instead of costly and time-consuming experiments, this paper focuses on using distributed dynamic simulations to analyze the real-time performance of network-based building control systems in ABs and improve the functions of the BACS technology. The paper also presents the development and design of a distributed dynamic simulation environment with the capability of representing the BACS architecture in simulation by run-time coupling two or more different software tools over a network. The application and capability of this new dynamic simulation environment are demonstrated by an experimental design in this paper.

Attenuation characteristics of monolayer graphene by Pi-and T-networks modeling of multilayer microstrip line

Institute of Scientific and Technical Information of China (English)

Pulkit Sharma; Sumit Pratap Singh; Kamlesh Patel

2017-01-01

The impedances of Pi-and T-networks are obtained from the measured S-parameters of the multilayer microstrip line by modeling as an attenuator.The changes in impedances have been analyzed for the properties of various superstrates at the microwave ranges.With graphene on glass and graphene on quartz loadings,the impedances have increased and shifted towards lower frequency more in Pi-network than T-network modeling.This shift has become more prominent at higher frequency for the graphene on glass than graphene on quartz.A little increase in attenuation is found for graphene on glass or quartz than bare glass and quartz.The present study can be extended to obtain attenuation characteristic of any thin film by simple experimental method in the microwave frequencies.

From Network to Research – Ten Years of Music Informatics, Performance and Aesthetics

DEFF Research Database (Denmark)

Frimodt-Møller, Søren; Grund, Cynthia M.; Jensen, Kristoffer

2011-01-01

This article briefly chronicles the history of the Nordic Network of Music Informatics, Performance and Aesthetics (NNIMIPA) and its roots in previous research networks and milieus. It explains how a cross-disciplinary network works and gives rise to research projects that bridge the gap between...

Advanced Communication Technology Satellite (ACTS) Very Small Aperture Terminal (VSAT) Network Control Performance

Science.gov (United States)

Coney, T. A.

1996-01-01

This paper discusses the performance of the network control function for the Advanced Communications Technology Satellite (ACTS) very small aperture terminal (VSAT) full mesh network. This includes control of all operational activities such as acquisition, synchronization, timing and rain fade compensation as well as control of all communications activities such as on-demand integrated services (voice, video, and date) connects and disconnects Operations control is provided by an in-band orderwire carried in the baseboard processor (BBP) control burst, the orderwire burst, the reference burst, and the uplink traffic burst. Communication services are provided by demand assigned multiple access (DAMA) protocols. The ACTS implementation of DAMA protocols ensures both on-demand and integrated voice, video and data services. Communications services control is also provided by the in-band orderwire but uses only the reference burst and the uplink traffic burst. The performance of the ACTS network control functions have been successfully tested during on-orbit checkout and in various VSAT networks in day to day operations. This paper discusses the network operations and services control performance.

An exploratory analysis of network characteristics and quality of interactions among public health collaboratives

Directory of Open Access Journals (Sweden)

Danielle M. Varda

2012-06-01

Full Text Available While the benefits of collaboration have become widely accepted and the practice of collaboration is growing within the public health system, a paucity of research exists that examines factors and mechanisms related to effective collaboration between public health and their partner organizations. The purpose of this paper is to address this gap by exploring the structural and organizational characteristics of public health collaboratives. Design and Methods. Using both social network analysis and traditional statistical methods, we conduct an exploratory secondary data analysis of 11 public health collaboratives chosen from across the United States. All collaboratives are part of the PARTNER (www.partnertool.net database. We analyze data to identify relational patterns by exploring the structure (the way that organizations connect and exchange relationships, in relation to perceptions of value and trust, explanations for varying reports of success, and factors related to outcomes. We describe the characteristics of the collaboratives, types of resource contributions, outcomes of the collaboratives, perceptions of success, and reasons for success. We found high variation and significant differences within and between these collaboratives including perceptions of success. There were significant relationships among various factors such as resource contributions, reasons cited for success, and trust and value perceived by organizations. We find that although the unique structure of each collaborative makes it challenging to identify a specific set of factors to determine when a collaborative will be successful, the organizational characteristics and interorganizational dynamics do appear to impact outcomes. We recommend a quality improvement process that suggests matching assessment to goals and developing action steps for performance improvement.

Evaluation of the Performance of Feedforward and Recurrent Neural Networks in Active Cancellation of Sound Noise

Directory of Open Access Journals (Sweden)

Mehrshad Salmasi

2012-07-01

Full Text Available Active noise control is based on the destructive interference between the primary noise and generated noise from the secondary source. An antinoise of equal amplitude and opposite phase is generated and combined with the primary noise. In this paper, performance of the neural networks is evaluated in active cancellation of sound noise. For this reason, feedforward and recurrent neural networks are designed and trained. After training, performance of the feedforwrad and recurrent networks in noise attenuation are compared. We use Elman network as a recurrent neural network. For simulations, noise signals from a SPIB database are used. In order to compare the networks appropriately, equal number of layers and neurons are considered for the networks. Moreover, training and test samples are similar. Simulation results show that feedforward and recurrent neural networks present good performance in noise cancellation. As it is seen, the ability of recurrent neural network in noise attenuation is better than feedforward network.

Energy efficient mechanisms for high-performance Wireless Sensor Networks

Science.gov (United States)

Alsaify, Baha'adnan

2009-12-01

Due to recent advances in microelectronics, the development of low cost, small, and energy efficient devices became possible. Those advances led to the birth of the Wireless Sensor Networks (WSNs). WSNs consist of a large set of sensor nodes equipped with communication capabilities, scattered in the area to monitor. Researchers focus on several aspects of WSNs. Such aspects include the quality of service the WSNs provide (data delivery delay, accuracy of data, etc...), the scalability of the network to contain thousands of sensor nodes (the terms node and sensor node are being used interchangeably), the robustness of the network (allowing the network to work even if a certain percentage of nodes fails), and making the energy consumption in the network as low as possible to prolong the network's lifetime. In this thesis, we present an approach that can be applied to the sensing devices that are scattered in an area for Sensor Networks. This work will use the well-known approach of using a awaking scheduling to extend the network's lifespan. We designed a scheduling algorithm that will reduce the delay's upper bound the reported data will experience, while at the same time keeps the advantages that are offered by the use of the awaking scheduling -- the energy consumption reduction which will lead to the increase in the network's lifetime. The wakeup scheduling is based on the location of the node relative to its neighbors and its distance from the Base Station (the terms Base Station and sink are being used interchangeably). We apply the proposed method to a set of simulated nodes using the "ONE Simulator". We test the performance of this approach with three other approaches -- Direct Routing technique, the well known LEACH algorithm, and a multi-parent scheduling algorithm. We demonstrate a good improvement on the network's quality of service and a reduction of the consumed energy.

Crosstalk-aware virtual network embedding over inter-datacenter optical networks with few-mode fibers

Science.gov (United States)

Huang, Haibin; Guo, Bingli; Li, Xin; Yin, Shan; Zhou, Yu; Huang, Shanguo

2017-12-01

Virtualization of datacenter (DC) infrastructures enables infrastructure providers (InPs) to provide novel services like virtual networks (VNs). Furthermore, optical networks have been employed to connect the metro-scale geographically distributed DCs. The synergistic virtualization of the DC infrastructures and optical networks enables the efficient VN service over inter-DC optical networks (inter-DCONs). While the capacity of the used standard single-mode fiber (SSMF) is limited by their nonlinear characteristics. Thus, mode-division multiplexing (MDM) technology based on few-mode fibers (FMFs) could be employed to increase the capacity of optical networks. Whereas, modal crosstalk (XT) introduced by optical fibers and components deployed in the MDM optical networks impacts the performance of VN embedding (VNE) over inter-DCONs with FMFs. In this paper, we propose a XT-aware VNE mechanism over inter-DCONs with FMFs. The impact of XT is considered throughout the VNE procedures. The simulation results show that the proposed XT-aware VNE can achieves better performances of blocking probability and spectrum utilization compared to conventional VNE mechanisms.