H∞ Filtering for Networked Markovian Jump Systems with Multiple Stochastic Communication Delays

Directory of Open Access Journals (Sweden)

Hui Dong

2015-01-01

Full Text Available This paper is concerned with the H∞ filtering for a class of networked Markovian jump systems with multiple communication delays. Due to the existence of communication constraints, the measurement signal cannot arrive at the filter completely on time, and the stochastic communication delays are considered in the filter design. Firstly, a set of stochastic variables is introduced to model the occurrence probabilities of the delays. Then based on the stochastic system approach, a sufficient condition is obtained such that the filtering error system is stable in the mean-square sense and with a prescribed H∞ disturbance attenuation level. The optimal filter gain parameters can be determined by solving a convex optimization problem. Finally, a simulation example is given to show the effectiveness of the proposed filter design method.

Stabilization of Teleoperation Systems with Communication Delays: An IMC Approach

Directory of Open Access Journals (Sweden)

Yuling Li

2018-01-01

Full Text Available The presence of time delays in communication introduces a limitation to the stability of bilateral teleoperation systems. This paper considers internal model control (IMC design of linear teleoperation system with time delays, and the stability of the closed-loop system is analyzed. It is shown that the stability is guaranteed delay-independently. The passivity assumption for external forces is removed for the proposed design of teleoperation systems. The behavior of the resulting teleoperation system is illustrated by simulations.

Hydrodynamic Cucker-Smale model with normalized communication weights and time delay

KAUST Repository

Choi, Young-Pil

2017-07-17

We study a hydrodynamic Cucker-Smale-type model with time delay in communication and information processing, in which agents interact with each other through normalized communication weights. The model consists of a pressureless Euler system with time delayed non-local alignment forces. We resort to its Lagrangian formulation and prove the existence of its global in time classical solutions. Moreover, we derive a sufficient condition for the asymptotic flocking behavior of the solutions. Finally, we show the presence of a critical phenomenon for the Eulerian system posed in the spatially one-dimensional setting.

The complexity of scheduling trees with communication delays

NARCIS (Netherlands)

Lenstra, J.K.; Veldhorst, M.; Veltman, B.

1996-01-01

We consider the problem of finding a minimum-length schedule onmmachines for a set ofnunit-length tasks with a forest of intrees as precedence relation, and with unit interprocessor communication delays. First, we prove that this problem is NP-complete; second, we derive a linear time algorithm for

Polar Cooperative Navigation Algorithm for Multi-Unmanned Underwater Vehicles Considering Communication Delays

Directory of Open Access Journals (Sweden)

Zheping Yan

2018-03-01

Full Text Available To solve the navigation accuracy problems of multi-Unmanned Underwater Vehicles (multi-UUVs in the polar region, a polar cooperative navigation algorithm for multi-UUVs considering communication delays is proposed in this paper. UUVs are important pieces of equipment in ocean engineering for marine development. For UUVs to complete missions, precise navigation is necessary. It is difficult for UUVs to establish true headings because of the rapid convergence of Earth meridians and the severe polar environment. Based on the polar grid navigation algorithm, UUV navigation in the polar region can be accomplished with the Strapdown Inertial Navigation System (SINS in the grid frame. To save costs, a leader-follower type of system is introduced in this paper. The leader UUV helps the follower UUVs to achieve high navigation accuracy. Follower UUVs correct their own states based on the information sent by the leader UUV and the relative position measured by ultra-short baseline (USBL acoustic positioning. The underwater acoustic communication delay is quantized by the model. In this paper, considering underwater acoustic communication delay, the conventional adaptive Kalman filter (AKF is modified to adapt to polar cooperative navigation. The results demonstrate that the polar cooperative navigation algorithm for multi-UUVs that considers communication delays can effectively navigate the sailing of multi-UUVs in the polar region.

Sleep/wake scheduling scheme for minimizing end-to-end delay in multi-hop wireless sensor networks

Directory of Open Access Journals (Sweden)

Madani Sajjad

2011-01-01

Full Text Available Abstract We present a sleep/wake schedule protocol for minimizing end-to-end delay for event driven multi-hop wireless sensor networks. In contrast to generic sleep/wake scheduling schemes, our proposed algorithm performs scheduling that is dependent on traffic loads. Nodes adapt their sleep/wake schedule based on traffic loads in response to three important factors, (a the distance of the node from the sink node, (b the importance of the node's location from connectivity's perspective, and (c if the node is in the proximity where an event occurs. Using these heuristics, the proposed scheme reduces end-to-end delay and maximizes the throughput by minimizing the congestion at nodes having heavy traffic load. Simulations are carried out to evaluate the performance of the proposed protocol, by comparing its performance with S-MAC and Anycast protocols. Simulation results demonstrate that the proposed protocol has significantly reduced the end-to-end delay, as well as has improved the other QoS parameters, like average energy per packet, average delay, packet loss ratio, throughput, and coverage lifetime.

Risks for communication delays and disorders in infants in an urban ...

African Journals Online (AJOL)

... factors associated with communication disorders in South Africa is limited. Objective. To identify and describe risk factors for communication delays in infants 0 - 12 months of age at Daspoort Polyclinic in Gauteng. Methods. A structured interview schedule was utilised to conduct an interview with the caregiver participants.

Peers without fears? Barriers to effective communication among primary care physicians and oncologists about diagnostic delays in cancer.

Science.gov (United States)

Lipitz-Snyderman, Allison; Kale, Minal; Robbins, Laura; Pfister, David; Fortier, Elizabeth; Pocus, Valerie; Chimonas, Susan; Weingart, Saul N

2017-11-01

Relatively little attention has been devoted to the role of communication between physicians as a mechanism for individual and organisational learning about diagnostic delays. This study's objective was to elicit physicians' perceptions about and experiences with communication among physicians regarding diagnostic delays in cancer. Qualitative analysis based on seven focus groups. Fifty-one physicians affiliated with three New York-based academic medical centres participated, with six to nine subjects per group. We used content analysis to identify commonalities among primary care physicians and specialists (ie, medical and surgical oncologists). Perceptions and experiences with physician-to-physician communication about delays in cancer diagnosis. Our analysis identified five major themes: openness to communication, benefits of communication, fears about giving and receiving feedback, infrastructure barriers to communication and overcoming barriers to communication. Subjects valued communication about cancer diagnostic delays, but they had many concerns and fears about providing and receiving feedback in practice. Subjects expressed reluctance to communicate if there was insufficient information to attribute responsibility, if it would have no direct benefit or if it would jeopardise their existing relationships. They supported sensitive approaches to conveying information, as they feared eliciting or being subject to feelings of incompetence or shame. Subjects also cited organisational barriers. They offered suggestions that might facilitate communication about delays. Addressing the barriers to communication among physicians about diagnostic delays is needed to promote a culture of learning across specialties and institutions. Supporting open and honest discussions about diagnostic delays may help build safer health systems. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use

Early detection of communication delays with the PEDS tools in at-risk South African infants

Directory of Open Access Journals (Sweden)

Jeannie van der Linde

2016-04-01

Method: A comparative study design evaluated the accuracy of the PEDS tools to detect communication delays, using an internationally accepted diagnostic assessment tool, the Rossetti Infant-Toddler Language Scale (RITLS. A convenience sample of 201 infants was selected at primary healthcare clinics. Results: Expressive and receptive language sensitivity scores were low across all three screens(ranging between 14% and 44%. The PEDS tools had high sensitivity (71% and specificity (73% ratings for the receptive and expressive language and socio-emotional domain in combination. Conclusion: In the sample population, the PEDS tools did not accurately detect receptive and expressive language delays; however, communication delays in general were identified. Future research determining accuracy of the PEDS, PEDS-Developmental Milestones and PEDS tools for children aged 2–5 years in detecting communication delays should be prioritised.

Using convolutional decoding to improve time delay and phase estimation in digital communications

Science.gov (United States)

Ormesher, Richard C [Albuquerque, NM; Mason, John J [Albuquerque, NM

2010-01-26

The time delay and/or phase of a communication signal received by a digital communication receiver can be estimated based on a convolutional decoding operation that the communication receiver performs on the received communication signal. If the original transmitted communication signal has been spread according to a spreading operation, a corresponding despreading operation can be integrated into the convolutional decoding operation.

Synchronization of Switched Neural Networks With Communication Delays via the Event-Triggered Control.

Science.gov (United States)

Wen, Shiping; Zeng, Zhigang; Chen, Michael Z Q; Huang, Tingwen

2017-10-01

This paper addresses the issue of synchronization of switched delayed neural networks with communication delays via event-triggered control. For synchronizing coupled switched neural networks, we propose a novel event-triggered control law which could greatly reduce the number of control updates for synchronization tasks of coupled switched neural networks involving embedded microprocessors with limited on-board resources. The control signals are driven by properly defined events, which depend on the measurement errors and current-sampled states. By using a delay system method, a novel model of synchronization error system with delays is proposed with the communication delays and event-triggered control in the unified framework for coupled switched neural networks. The criteria are derived for the event-triggered synchronization analysis and control synthesis of switched neural networks via the Lyapunov-Krasovskii functional method and free weighting matrix approach. A numerical example is elaborated on to illustrate the effectiveness of the derived results.

Attitude coordination for spacecraft formation with multiple communication delays

Directory of Open Access Journals (Sweden)

Guo Yaohua

2015-04-01

Full Text Available Communication delays are inherently present in information exchange between spacecraft and have an effect on the control performance of spacecraft formation. In this work, attitude coordination control of spacecraft formation is addressed, which is in the presence of multiple communication delays between spacecraft. Virtual system-based approach is utilized in case that a constant reference attitude is available to only a part of the spacecraft. The feedback from the virtual systems to the spacecraft formation is introduced to maintain the formation. Using backstepping control method, input torque of each spacecraft is designed such that the attitude of each spacecraft converges asymptotically to the states of its corresponding virtual system. Furthermore, the backstepping technique and the Lyapunov–Krasovskii method contribute to the control law design when the reference attitude is time-varying and can be obtained by each spacecraft. Finally, effectiveness of the proposed methodology is illustrated by the numerical simulations of a spacecraft formation.

Cucker-Smale model with normalized communication weights and time delay

KAUST Repository

Choi, Young-Pil; Haskovec, Jan

2017-01-01

We study a Cucker-Smale-type system with time delay in which agents interact with each other through normalized communication weights. We construct a Lyapunov functional for the system and provide sufficient conditions for asymptotic flocking, i

A simulation study of the effects of communication delay on air traffic control

Science.gov (United States)

1990-09-01

This study was conducted to examine the impacts of voice communications delays : characteristic of Voice Switching and Control System (VSCS) and satellite : communications systems on air traffic system performance, controller stress : and workload, a...

Stable Formation Control of Multi-Robot System with Communication Delay

Directory of Open Access Journals (Sweden)

Limei Jiang

2012-03-01

Full Text Available In this paper, a distributed formation control algorithm with delayed information exchange is discussed. The algorithm, which is derived from the flocking behaviour of birds and consensus theory, enables robots to move in formation at a desired velocity. After a series of orthogonal transformations to the original formation system, the upper bound tolerable delay is obtained by using matrix theory and the Nyquist criterion. According to the results, the upper bound tolerable delay depends on the control parameters and eigenvalues of the Laplacian matrix. Therefore, the effect of the parameters on the maximum tolerable delay is analysed, obtaining the following conclusions: the upper bound tolerable delay is proportional to the parameters associated with the velocity, inversely proportional to the parameters associated with the position, and inversely proportional to the difference between the eigenvalue of Laplacian matrix and 1. The simulation results of a four-robot formation system with different communication delays verify the effectiveness of the formation control algorithm and the correctness of the theoretical analysis.

Remote optimal state estimation over communication channels with random delays

KAUST Repository

Mahmoud, Magdi S.; Al-Sunni, Fouad; Liu, Bo

2014-01-01

This paper considers the optimal estimation of linear systems over unreliable communication channels with random delays. In this work, it is assumed that the system to be estimated is far away from the filter. The observations of the system

Synchronization and bidirectional communication without delay line using strong mutually coupled semiconductor lasers

Science.gov (United States)

Li, Guang-Hui; Wang, An-Bang; Feng, Ye; Wang, Yang

2010-07-01

This paper numerically demonstrates synchronization and bidirectional communication without delay line by using two semiconductor lasers with strong mutual injection in a face-to-face configuration. These results show that both of the two lasers' outputs synchronize with their input chaotic carriers. In addition, simulations demonstrate that this kind of synchronization can be used to realize bidirectional communications without delay line. Further studies indicate that within a small deviation in message amplitudes of two sides (±6%), the message can be extracted with signal-noise-ratio more than 10 dB; and the signal-noise-ratio is extremely sensitive to the message rates mismatch of two sides, which may be used as a key of bidirectional communication.

Synchronization and bidirectional communication without delay line using strong mutually coupled semiconductor lasers

International Nuclear Information System (INIS)

Guang-Hui, Li; An-Bang, Wang; Ye, Feng; Yang, Wang

2010-01-01

This paper numerically demonstrates synchronization and bidirectional communication without delay line by using two semiconductor lasers with strong mutual injection in a face-to-face configuration. These results show that both of the two lasers' outputs synchronize with their input chaotic carriers. In addition, simulations demonstrate that this kind of synchronization can be used to realize bidirectional communications without delay line. Further studies indicate that within a small deviation in message amplitudes of two sides (±6%), the message can be extracted with signal-noise-ratio more than 10 dB; and the signal-noise-ratio is extremely sensitive to the message rates mismatch of two sides, which may be used as a key of bidirectional communication. (general)

Transmission Delay Modeling of Packet Communication over Digital Subscriber Line

Directory of Open Access Journals (Sweden)

Jiri Vodrazka

2013-01-01

Full Text Available Certain multimedia and voice services, such as VoIP, IPTV, etc., are significantly delay sensitive and their performance is influenced by the overall transmission delay and its variance. One of the most common solutions used in access networks are xDSL lines, especially ADSL2+ or VDSL2. Although these subscriber lines also use packet communication, there are several differences and mechanisms, which influence their resulting delay. Their delay characteristics are also dependent on the individual settings of each xDSL provider, therefore we decided to investigate this area for typical commercially available lines in Czech Republic. Based on the measured values and experiments with real ADSL2+ lines we also developed a potential modeling method, which is presented in this article as well. The parameters for packet jitter based on the generalized Pareto distribution were modeled.

UAS Air Traffic Controller Acceptability Study-2: Effects of Communications Delays and Winds in Simulation

Science.gov (United States)

Comstock, James R., Jr.; Ghatas, Rania W.; Consiglio, Maria C.; Chamberlain, James P.; Hoffler, Keith D.

2016-01-01

This study evaluated the effects of Communications Delays and Winds on Air Traffic Controller ratings of acceptability of horizontal miss distances (HMDs) for encounters between UAS and manned aircraft in a simulation of the Dallas-Ft. Worth East-side airspace. Fourteen encounters per hour were staged in the presence of moderate background traffic. Seven recently retired controllers with experience at DFW served as subjects. Guidance provided to the UAS pilots for maintaining a given HMD was provided by information from self-separation algorithms displayed on the Multi-Aircraft Simulation System. Winds tested did not affect the acceptability ratings. Communications delays tested included 0, 400, 1200, and 1800 msec. For longer communications delays, there were changes in strategy and communications flow that were observed and reported by the controllers. The aim of this work is to provide useful information for guiding future rules and regulations applicable to flying UAS in the NAS.

Networked control systems with communication constraints :tradeoffs between sampling intervals, delays and performance

NARCIS (Netherlands)

Heemels, W.P.M.H.; Teel, A.R.; Wouw, van de N.; Nesic, D.

2010-01-01

There are many communication imperfections in networked control systems (NCS) such as varying transmission delays, varying sampling/transmission intervals, packet loss, communication constraints and quantization effects. Most of the available literature on NCS focuses on only some of these aspects,

Understanding the Effect of Audio Communication Delay on Distributed Team Interaction

Science.gov (United States)

2013-06-01

means for members to socialize and learn about each other, engenders development cooperative relationships, and lays a foundation for future interaction...length will result in increases in task completion time and mental workload. 3. Audiovisual technology will moderate the effect of communication...than audio alone. 4. Audiovisual technology will moderate the effect of communication delays such that task completion time and mental workload will

Minimizing SIP Session Re-Setup Delay over Wireless Link in 3G Handover Scenarios

Directory of Open Access Journals (Sweden)

Moon Bongkyo

2010-01-01

Full Text Available The delay in transmitting SIP messages over the wireless link for session resetup at handover is still major bottleneck for interactive multimedia service. In this paper, a proxy agent-based scheme is proposed to minimize the SIP session setup delay over a wireless link in 3G inter-subnet handover scenarios. This scheme is based on the two characteristics. One is that the major factor of SIP session re-setup delay is generally caused by the retransmissions in the unreliable wireless links, and the other is that most of the fields in request messages as well as response messages are duplicated when a set of SIP messages are exchanged during session re-setup procedure. In this scheme, no change is required in the SIP message processing except for the proxy agents in both BS and MH.

Limitations in the design of ancillary service markets imposed by communication network delays

NARCIS (Netherlands)

Hermans, R.M.; Jokic, A.; Bosch, van den P.P.J.; Frunt, J.; Kamphuis, I.G.; Warmer, C.J.

2010-01-01

Real-time balancing of the European electricity grid will become increasingly dependent on market-based control mechanisms that are enabled by connecting millions of prosumers to an open communication network. The use of communication systems inevitably introduces delays in the energy balancing

Remote optimal state estimation over communication channels with random delays

KAUST Repository

Mahmoud, Magdi S.

2014-01-22

This paper considers the optimal estimation of linear systems over unreliable communication channels with random delays. In this work, it is assumed that the system to be estimated is far away from the filter. The observations of the system are capsulized without time stamp and then transmitted to the network node at which the filter is located. The probabilities of time delays are assumed to be known. The event-driven estimation scheme is applied in this paper and the estimate of the states is updated only at each time instant when any measurement arrives. To capture the feature of communication, the system considered is augmented, and the arrived measurements are regarded as the uncertain observations of the augmented system. The corresponding optimal estimation algorithm is proposed and additionally, a numerical simulation represents the performance of this work. © 2014 The authors. Published by Oxford University Press on behalf of the Institute of Mathematics and its Applications. All rights reserved.

Dynamic Resource Allocation and Access Class Barring Scheme for Delay-Sensitive Devices in Machine to Machine (M2M) Communications.

Science.gov (United States)

Li, Ning; Cao, Chao; Wang, Cong

2017-06-15

Supporting simultaneous access of machine-type devices is a critical challenge in machine-to-machine (M2M) communications. In this paper, we propose an optimal scheme to dynamically adjust the Access Class Barring (ACB) factor and the number of random access channel (RACH) resources for clustered machine-to-machine (M2M) communications, in which Delay-Sensitive (DS) devices coexist with Delay-Tolerant (DT) ones. In M2M communications, since delay-sensitive devices share random access resources with delay-tolerant devices, reducing the resources consumed by delay-sensitive devices means that there will be more resources available to delay-tolerant ones. Our goal is to optimize the random access scheme, which can not only satisfy the requirements of delay-sensitive devices, but also take the communication quality of delay-tolerant ones into consideration. We discuss this problem from the perspective of delay-sensitive services by adjusting the resource allocation and ACB scheme for these devices dynamically. Simulation results show that our proposed scheme realizes good performance in satisfying the delay-sensitive services as well as increasing the utilization rate of the random access resources allocated to them.

Delay Tolerance in Underwater Wireless Communications: A Routing Perspective

Directory of Open Access Journals (Sweden)

Safdar Hussain Bouk

2016-01-01

Full Text Available Similar to terrestrial networks, underwater wireless networks (UWNs also aid several critical tasks including coastal surveillance, underwater pollution detection, and other maritime applications. Currently, once underwater sensor nodes are deployed at different levels of the sea, it is nearly impossible or very expensive to reconfigure the hardware, for example, battery. Taking this issue into account, considerable amount of research has been carried out to ensure minimum energy costs and reliable communication between underwater nodes and base stations. As a result, several different network protocols were proposed for UWN, including MAC, PHY, transport, and routing. Recently, a new paradigm was introduced claiming that the intermittent nature of acoustic channel and signal resulted in designing delay tolerant routing schemes for the UWN, known as an underwater delay tolerant network. In this paper, we provide a comprehensive survey of underwater routing protocols with emphasis on the limitations, challenges, and future open issues in the context of delay tolerant network routing.

Pointing with a One-Eyed Cursor for Supervised Training in Minimally Invasive Robotic Surgery

DEFF Research Database (Denmark)

Kibsgaard, Martin; Kraus, Martin

2016-01-01

Pointing in the endoscopic view of a surgical robot is a natural and effcient way for instructors to communicate with trainees in robot-assisted minimally invasive surgery. However, pointing in a stereo-endoscopic view can be limited by problems such as video delay, double vision, arm fatigue......-day training units in robot- assisted minimally invasive surgery on anaesthetised pigs....

Risks for communication delays and disorders in infants in an urban ...

African Journals Online (AJOL)

may result in conditions such as fetal alcohol spectrum disorder. (FASD).[4,5] South ... communication delays or disorders in infants aged 0 12 months in an urban PHC ..... Results from the CHARGE (Childhood Autism Risks from Genetics and ...

Distributed Containment Control of Networked Fractional-Order Systems with Delay-Dependent Communications

Directory of Open Access Journals (Sweden)

Xueliang Liu

2012-01-01

Full Text Available This paper is concerned with a containment problem of networked fractional-order system with multiple leaders under a fixed directed interaction graph. Based on the neighbor rule, a distributed protocol is proposed in delayed communication channels. By employing the algebraic graph theory, matrix theory, Nyquist stability theorem, and frequency domain method, it is analytically proved that the whole follower agents will flock to the convex hull which is formed by the leaders. Furthermore, a tight upper bound on the communication time-delay that can be tolerated in the dynamic network is obtained. As a special case, the interconnection topology under the undirected case is also discussed. Finally, some numerical examples with simulations are presented to demonstrate the effectiveness and correctness of the theoretical results.

Cucker-Smale model with normalized communication weights and time delay

KAUST Repository

Choi, Young-Pil

2017-03-06

We study a Cucker-Smale-type system with time delay in which agents interact with each other through normalized communication weights. We construct a Lyapunov functional for the system and provide sufficient conditions for asymptotic flocking, i.e., convergence to a common velocity vector. We also carry out a rigorous limit passage to the mean-field limit of the particle system as the number of particles tends to infinity. For the resulting Vlasov-type equation we prove the existence, stability and large-time behavior of measure-valued solutions. This is, to our best knowledge, the first such result for a Vlasov-type equation with time delay. We also present numerical simulations of the discrete system with few particles that provide further insights into the flocking and oscillatory behaviors of the particle velocities depending on the size of the time delay.

A Simple Snap Oscillator with Coexisting Attractors, Its Time-Delayed Form, Physical Realization, and Communication Designs

Science.gov (United States)

Rajagopal, Karthikeyan; Jafari, Sajad; Akgul, Akif; Karthikeyan, Anitha; Çiçek, Serdar; Shekofteh, Yasser

2018-05-01

In this paper, we report a novel chaotic snap oscillator with one nonlinear function. Dynamic analysis of the system shows the existence of bistability. To study the time delay effects on the proposed snap oscillator, we introduce multiple time delay in the fourth state equation. Investigation of dynamical properties of the time-delayed system shows that the snap oscillator exhibits the same multistable properties as the nondelayed system. The new multistable hyperjerk chaotic system has been tested in chaos shift keying and symmetric choc shift keying modulated communication designs for engineering applications. It has been determined that the symmetric chaos shift keying modulated communication system implemented with the new chaotic system is more successful than the chaos shift keying modulation for secure communication. Also, circuit implementation of the chaotic snap oscillator with tangent function is carried out showing its feasibility.

Phase-coherence transitions and communication in the gamma range between delay-coupled neuronal populations.

Directory of Open Access Journals (Sweden)

Alessandro Barardi

2014-07-01

Full Text Available Synchronization between neuronal populations plays an important role in information transmission between brain areas. In particular, collective oscillations emerging from the synchronized activity of thousands of neurons can increase the functional connectivity between neural assemblies by coherently coordinating their phases. This synchrony of neuronal activity can take place within a cortical patch or between different cortical regions. While short-range interactions between neurons involve just a few milliseconds, communication through long-range projections between different regions could take up to tens of milliseconds. How these heterogeneous transmission delays affect communication between neuronal populations is not well known. To address this question, we have studied the dynamics of two bidirectionally delayed-coupled neuronal populations using conductance-based spiking models, examining how different synaptic delays give rise to in-phase/anti-phase transitions at particular frequencies within the gamma range, and how this behavior is related to the phase coherence between the two populations at different frequencies. We have used spectral analysis and information theory to quantify the information exchanged between the two networks. For different transmission delays between the two coupled populations, we analyze how the local field potential and multi-unit activity calculated from one population convey information in response to a set of external inputs applied to the other population. The results confirm that zero-lag synchronization maximizes information transmission, although out-of-phase synchronization allows for efficient communication provided the coupling delay, the phase lag between the populations, and the frequency of the oscillations are properly matched.

Delay reduction in multi-hop device-to-device communication using network coding

KAUST Repository

Douik, Ahmed S.; Sorour, Sameh; Al-Naffouri, Tareq Y.; Yang, Hong-Chuan; Alouini, Mohamed-Slim

2015-01-01

This paper considers the problem of reducing the broadcast delay of wireless networks using instantly decodable network coding (IDNC) based device-to-device (D2D) communications. In D2D-enabled networks, devices help hasten the recovery of the lost

Stability of formation control using a consensus protocol under directed communications with two time delays and delay scheduling

Science.gov (United States)

Cepeda-Gomez, Rudy; Olgac, Nejat

2016-01-01

We consider a linear algorithm to achieve formation control in a group of agents which are driven by second-order dynamics and affected by two rationally independent delays. One of the delays is in the position and the other in the velocity information channels. These delays are taken as constant and uniform throughout the system. The communication topology is assumed to be directed and fixed. The formation is attained by adding a supplementary control term to the stabilising consensus protocol. In preparation for the formation control logic, we first study the stability of the consensus, using the recent cluster treatment of characteristic roots (CTCR) paradigm. This effort results in a unique depiction of the non-conservative stability boundaries in the domain of the delays. However, CTCR requires the knowledge of the potential stability switching loci exhaustively within this domain. The creation of these loci is done in a new surrogate coordinate system, called the 'spectral delay space (SDS)'. The relative stability is also investigated, which has to do with the speed of reaching consensus. This step leads to a paradoxical control design concept, called the 'delay scheduling', which highlights the fact that the group behaviour may be enhanced by increasing the delays. These steps lead to a control strategy to establish a desired group formation that guarantees spacing among the agents. Example case studies are presented to validate the underlying analytical derivations.

Examination of Communication Delays on Team Performance: Utilizing the International Space Station (ISS) as a Test Bed for Analog Research

Science.gov (United States)

Keeton, K. E.; Slack, K, J.; Schmidt, L. L.; Ploutz-Snyder, R.; Baskin, P.; Leveton, L. B.

2011-01-01

Operational conjectures about space exploration missions of the future indicate that space crews will need to be more autonomous from mission control and operate independently. This is in part due to the expectation that communication quality between the ground and exploration crews will be more limited and delayed. Because of potential adverse effects on communication quality, both researchers and operational training and engineering experts have suggested that communication delays and the impact these delays have on the quality of communications to the crew will create performance decrements if crews are not given adequate training and tools to support more autonomous operations. This presentation will provide an overview of a research study led by the Behavioral Health and Performance Element (BHP) of the NASA Human Research Program that examines the impact of implementing a communication delay on ISS on individual and team factors and outcomes, including performance and related perceptions of autonomy. The methodological design, data collection efforts, and initial results of this study to date will be discussed . The results will focus on completed missions, DRATS and NEEMO15. Lessons learned from implementing this study within analog environments will also be discussed. One lesson learned is that the complexities of garnishing a successful data collection campaign from these high fidelity analogs requires perseverance and a strong relationship with operational experts. Results of this study will provide a preliminary understanding of the impact of communication delays on individual and team performance as well as an insight into how teams perform and interact in a space-like environment . This will help prepare for implementation of communication delay tests on the ISS, targeted for Increment 35/36.

A reliable, delay bounded and less complex communication protocol for multicluster FANETs

Directory of Open Access Journals (Sweden)

Wajiya Zafar

2017-02-01

Full Text Available Recently, Flying Ad-hoc Networks (FANETs, enabling ad-hoc networking between Unmanned Aerial Vehicles (UAVs is gaining importance in several military and civilian applications. The sensitivity of the applications requires adaptive; efficient; delay bounded and scalable communication network among UAVs for data transmission. Due to communication protocol complexity; rigidity; cost of commercial-off-the-shelf (COT components; limited radio bandwidth; high mobility and computational resources; maintaining the desired level of Quality of Service (QoS becomes a daunting task. For the first time in this research we propose multicluster FANETs for efficient network management; the proposed scheme considerably reduces communication cost and optimizes network performance as well as exploit low power; less complex and low cost IEEE 802.15.4 (MAC protocol for intercluster and intracluster communication. In this research both beacon enabled mode and beaconless modes have been investigated with Guaranteed Time Slots (GTS and virtual Time Division Multiple Access (TDMA respectively. The methodology plays a key role towards reserving bandwidth for latency critical applications; eliminate collisions and medium access delays. Moreover analysis ad-hoc routing protocols including two proactive (OLSR, DSDV and one reactive (AODV is also presented. The results shows that the proposed scheme guarantees high packet delivery ratios while maintaining acceptable levels of latency requirements comparable with more complex and dedicatedly designed protocols in literature.

Synchronization of the chaotic secure communication system with output state delay

International Nuclear Information System (INIS)

Changchien, S.-K.; Huang, C.-K.; Nien, H.-H.; Shieh, H.-W.

2009-01-01

In this paper, we utilize a proper Lyapunov function and Lyapunov theorem, combined with LMIs method, in order to design a controller L, which ensures the synchronization between the transmission and the reception ends of the chaotic secure communication system with time-delay of output state. Meanwhile, for the purpose of increasing communication security, we encrypt and decrypt the original to-be-transmitted message with the techniques of n-shift cipher and public key. The result of simulation shows that the proposed method is able to synchronize the transmission and the reception ends of the system, and moreover, to recover the original message at the reception end. Therefore, the method proposed in this paper is effective and feasible to apply in the chaotic secure communication system.

Novel Wireless-Communicating Textiles Made from Multi-Material and Minimally-Invasive Fibers

Directory of Open Access Journals (Sweden)

Stepan Gorgutsa

2014-10-01

Full Text Available The ability to integrate multiple materials into miniaturized fiber structures enables the realization of novel biomedical textile devices with higher-level functionalities and minimally-invasive attributes. In this work, we present novel textile fabrics integrating unobtrusive multi-material fibers that communicate through 2.4 GHz wireless networks with excellent signal quality. The conductor elements of the textiles are embedded within the fibers themselves, providing electrical and chemical shielding against the environment, while preserving the mechanical and cosmetic properties of the garments. These multi-material fibers combine insulating and conducting materials into a well-defined geometry, and represent a cost-effective and minimally-invasive approach to sensor fabrics and bio-sensing textiles connected in real time to mobile communications infrastructures, suitable for a variety of health and life science applications.

Minimization of Delay Costs in the Realization of Production Orders in Two-Machine System

Science.gov (United States)

Dylewski, Robert; Jardzioch, Andrzej; Dworak, Oliver

2018-03-01

The article presents a new algorithm that enables the allocation of the optimal scheduling of the production orders in the two-machine system based on the minimum cost of order delays. The formulated algorithm uses the method of branch and bounds and it is a particular generalisation of the algorithm enabling for the determination of the sequence of the production orders with the minimal sum of the delays. In order to illustrate the proposed algorithm in the best way, the article contains examples accompanied by the graphical trees of solutions. The research analysing the utility of the said algorithm was conducted. The achieved results proved the usefulness of the proposed algorithm when applied to scheduling of orders. The formulated algorithm was implemented in the Matlab programme. In addition, the studies for different sets of production orders were conducted.

Impact of communication delays to and from the International Space Station on self-reported individual and team behavior and performance: A mixed-methods study

Science.gov (United States)

Kintz, Natalie M.; Chou, Chih-Ping; Vessey, William B.; Leveton, Lauren B.; Palinkas, Lawrence A.

2016-12-01

Deep space explorations will involve significant delays in communication to and from Earth that will likely impact individual and team outcomes. However, the extent of these impacts and the appropriate countermeasures for their mitigation remain largely unknown. This study utilized the International Space Station (ISS), a high-fidelity analog for deep space, as a research platform to assess the impact of communication delays on individual and team performance, mood, and behavior. Three astronauts on the ISS and 18 mission support personnel performed tasks with and without communication delays (50-s one-way) during a mission lasting 166 days. Self-reported assessments of individual and team performance and mood were obtained after each task. Secondary outcomes included communication quality and task autonomy. Qualitative data from post-mission interviews with astronauts were used to validate and expand on quantitative data, and to elicit recommendations for countermeasures. Crew well-being and communication quality were significantly reduced in communication delay tasks compared to control. Communication delays were also significantly associated with increased individual stress/frustration. Qualitative data suggest communication delays impacted operational outcomes (i.e. task efficiency), teamwork processes (i.e. team/task coordination) and mood (i.e. stress/frustration), particularly when tasks involved high task-related communication demands, either because of poor communication strategies or low crew autonomy. Training, teamwork, and technology-focused countermeasures were identified to mitigate or prevent adverse impacts.

Measuring propagation delay over a coded serial communication channel using FPGAs

International Nuclear Information System (INIS)

Jansweijer, P.P.M.; Peek, H.Z.

2011-01-01

Measurement and control applications are increasingly using distributed system technologies. In such applications, which may be spread over large distances, it is often necessary to synchronize system timing and know with great precision the time offsets between parts of the system. Measuring the propagation delay over a coded serial communication channel using serializer/deserializer (SerDes) functionality in FPGAs is described. The propagation delay between transmitter and receiver is measured with a resolution of a single unit interval (i.e. a serial link running at 3.125 Gbps provides a 320 ps resolution). The technique has been demonstrated to work over 100 km fibre to verify the feasibility for application in the future KM3NeT telescope.

Passive Transparency Compensation for Bilateral Teleoperators with Communication Delays

Directory of Open Access Journals (Sweden)

Erick J. Rodríguez-Seda

2015-01-01

Full Text Available One of the main challenges in the realization of time-delayed bilateral teleoperators is the stable adaptation of transparency when the remote environmental dynamics are time-varying. In this paper, we propose a bilateral control strategy that passively adjusts the transparency of the system when the slave robot transitions between two different environments. The proposed controller exploits the effect that the wave impedance (a design parameter of the passivity-based scattering transformation has on transparency without comprising closed-loop stability, regardless of time-varying communication delays. To properly adjust transparency, the control scheme smoothly switches the wave impedance parameter between a low value, ideal for free motion, and a sufficiently large value, suited for hard-contact tasks. We show that, by adopting this strategy, the transmitted impedance to the operator approximates more closely the environmental impedance value. Furthermore, we theoretically prove master-slave position coordination and force tracking under different scenarios. Simulation results illustrate the effectiveness of the proposed control strategy.

Increasing Social Behaviors in Young Children with Social-Communication Delays in a Group Arrangement in Preschool

Science.gov (United States)

Lane, Justin D.; Gast, David L.; Ledford, Jennifer R.; Shepley, Collin

2017-01-01

Young children with disabilities are less likely to display age-appropriate social behaviors than same-age peers with typical social development, especially children who display social-communication delays. In this study, two concurrently operating single case designs were used to evaluate the use of progressive time delay (PTD) to teach children…

UAS Air Traffic Controller Acceptability Study. 2; Evaluating Detect and Avoid Technology and Communication Delays in Simulation

Science.gov (United States)

Comstock, James R., Jr.; Ghatas, Rania W.; Consiglio, Maria C.; Chamberlain, James P.; Hoffler, Keith D.

2015-01-01

This study evaluated the effects of communications delays and winds on air traffic controller ratings of acceptability of horizontal miss distances (HMDs) for encounters between Unmanned Aircraft Systems (UAS) and manned aircraft in a simulation of the Dallas-Ft. Worth (DFW) airspace. Fourteen encounters per hour were staged in the presence of moderate background traffic. Seven recently retired controllers with experience at DFW served as subjects. Guidance provided to the UAS pilots for maintaining a given HMD was provided by information from Detect and Avoid (DAA) self-separation algorithms (Stratway+) displayed on the Multi-Aircraft Control System. This guidance consisted of amber "bands" on the heading scale of the UAS navigation display indicating headings that would result in a loss of well clear between the UAS and nearby traffic. Winds tested were successfully handled by the DAA algorithms and did not affect the controller acceptability ratings of the HMDs. Voice communications delays for the UAS were also tested and included one-way delay times of 0, 400, 1200, and 1800 msec. For longer communications delays, there were changes in strategy and communications flow that were observed and reported by the controllers. The aim of this work is to provide useful information for guiding future rules and regulations applicable to flying UAS in the NAS. Information from this study will also be of value to the Radio Technical Commission for Aeronautics (RTCA) Special Committee 228 - Minimum Performance Standards for UAS.

Comparing Pictures and Videos for Teaching Action Labels to Children with Communication Delays

Science.gov (United States)

Schebell, Shannon; Shepley, Collin; Mataras, Theologia; Wunderlich, Kara

2018-01-01

Children with communication delays often display difficulties labeling stimuli in their environment, particularly related to actions. Research supports direct instruction with video and picture stimuli for increasing children's action labeling repertoires; however, no studies have compared which type of stimuli results in more efficient,…

Bipartite consensus for multi-agent systems with antagonistic interactions and communication delays

Science.gov (United States)

Guo, Xing; Lu, Jianquan; Alsaedi, Ahmed; Alsaadi, Fuad E.

2018-04-01

This paper studies the consensus problems over signed digraphs with arbitrary finite communication delays. For the considered system, the information flow is directed and only locally delayed information can be used for each node. We derive that bipartite consensus of this system can be realized when the associated signed digraph is strongly connected. Furthermore, for structurally balanced networks, this paper studies the pinning partite consensus for the considered system. we design a pinning scheme to pin any one agent in the signed network, and obtain that the network achieves pinning bipartite consensus with any initial conditions. Finally, two examples are provided to demonstrate the effectiveness of our main results.

Optimal Joint Expected Delay Forwarding in Delay Tolerant Networks

OpenAIRE

Jia Xu; Xin Feng; Wen Jun Yang; Ru Chuan Wang; Bing Qing Han

2013-01-01

Multicopy forwarding schemes have been employed in delay tolerant network (DTN) to improve the delivery delay and delivery rate. Much effort has been focused on reducing the routing cost while retaining high performance. This paper aims to provide an optimal joint expected delay forwarding (OJEDF) protocol which minimizes the expected delay while satisfying a certain constant on the number of forwardings per message. We propose a comprehensive forwarding metric called joint expected delay (JE...

Security-enhanced chaos communication with time-delay signature suppression and phase encryption.

Science.gov (United States)

Xue, Chenpeng; Jiang, Ning; Lv, Yunxin; Wang, Chao; Li, Guilan; Lin, Shuqing; Qiu, Kun

2016-08-15

A security-enhanced chaos communication scheme with time delay signature (TDS) suppression and phase-encrypted feedback light is proposed, in virtue of dual-loop feedback with independent high-speed phase modulation. We numerically investigate the property of TDS suppression in the intensity and phase space and quantitatively discuss security of the proposed system by calculating the bit error rate of eavesdroppers who try to crack the system by directly filtering the detected signal or by using a similar semiconductor laser to synchronize the link signal and extract the data. The results show that TDS embedded in the chaotic carrier can be well suppressed by properly setting the modulation frequency, which can keep the time delay a secret from the eavesdropper. Moreover, because the feedback light is encrypted, without the accurate time delay and key, the eavesdropper cannot reconstruct the symmetric operation conditions and decode the correct data.

Communication growth in minimally verbal children with ASD: The importance of interaction.

Science.gov (United States)

DiStefano, Charlotte; Shih, Wendy; Kaiser, Ann; Landa, Rebecca; Kasari, Connie

2016-10-01

Little is known about language development in children with Autism Spectrum Disorders (ASD) who remain minimally verbal past age 5. While there is evidence that children can develop language after age 5, we lack detailed information. Studies of this population generally focus on discrete language skills without addressing broader social-communication abilities. As communication and social deficits are both inherent to ASD, an examination of not only what language skills are acquired, but how those skills are used in interactions is relevant. Research in typical development has examined how communication interchanges (unbroken back-and-forth exchanges around a unified purpose) develop, which can be used as a framework for studying minimally verbal children. This study examined the interchange use by 55 children with ASD over the course of a 6-month play and engagement-based communication intervention. Half of the children received intervention sessions that also incorporated a speech-generating device (SGD). Interchanges were coded by: frequency, length, function, and initiator (child or adult). Results indicated that children initiated a large proportion of interchanges and this proportion increased over time. The average length and number of interchanges increased over time, with children in the SGD group showing even greater growth. Finally, children's total number of interchanges at baseline was positively associated with their spoken language gains over the course of intervention. This study supports the crucial relationship between social engagement and expressive language development, and highlights the need to include sustained communication interchanges as a target for intervention with this population. Autism Res 2016, 9: 1093-1102. © 2016 International Society for Autism Research, Wiley Periodicals, Inc. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

Communication Delays in the Cooperative Control of Wide Area Search Munitions Via Iterative Network Flow

National Research Council Canada - National Science Library

Mitchell, Jason

2003-01-01

.... This model is used to study the effect of communication delays on the performance of an iteractive network flow optimization model that results in a sequence of linear programs for the optimal...

Small-Signal Analysis of the Microgrid Secondary Control Considering a Communication Time Delay

DEFF Research Database (Denmark)

Coelho, Ernane Antônio Alves; Wu, Dan; Guerrero, Josep M.

2016-01-01

This paper presents a small-signal analysis of an islanded microgrid composed of two or more voltage-source inverters connected in parallel. The primary control of each inverter is integrated through an internal current and voltage loops using proportional resonant compensators, a virtual impedance......, and an external power controller based on frequency and voltage droops. The frequency restoration function is implemented at the secondary control level, which executes a consensus algorithm that consists of a load-frequency control and a single time delay communication network. The consensus network consists...... the behavior of the system considering control parameters and time delay variation....

Sleep/wake scheduling scheme for minimizing end-to-end delay in multi-hop wireless sensor networks

OpenAIRE

Madani Sajjad; Nazir Babar; Hasbullah Halabi

2011-01-01

Abstract We present a sleep/wake schedule protocol for minimizing end-to-end delay for event driven multi-hop wireless sensor networks. In contrast to generic sleep/wake scheduling schemes, our proposed algorithm performs scheduling that is dependent on traffic loads. Nodes adapt their sleep/wake schedule based on traffic loads in response to three important factors, (a) the distance of the node from the sink node, (b) the importance of the node's location from connectivity's perspective, and...

Asynchronous anti-noise hyper chaotic secure communication system based on dynamic delay and state variables switching

Energy Technology Data Exchange (ETDEWEB)

Liu, Hongjun [Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 (China); Weifang Vocational College, Weifang 261041 (China); Wang, Xingyuan, E-mail: wangxy@dlut.edu.cn [Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 (China); Zhu, Quanlong [Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 (China)

2011-07-18

This Letter designs an asynchronous hyper chaotic secure communication system, which possesses high stability against noise, using dynamic delay and state variables switching to ensure the high security. The relationship between the bit error ratio (BER) and the signal-to-noise ratio (SNR) is analyzed by simulation tests, the results show that the BER can be ensured to reach zero by proportionally adjusting the amplitudes of the state variables and the noise figure. The modules of the transmitter and receiver are implemented, and numerical simulations demonstrate the effectiveness of the system. -- Highlights: → Asynchronous anti-noise hyper chaotic secure communication system. → Dynamic delay and state switching to ensure the high security. → BER can reach zero by adjusting the amplitudes of state variables and noise figure.

Local empathy provides global minimization of congestion in communication networks

Science.gov (United States)

Meloni, Sandro; Gómez-Gardeñes, Jesús

2010-11-01

We present a mechanism to avoid congestion in complex networks based on a local knowledge of traffic conditions and the ability of routers to self-coordinate their dynamical behavior. In particular, routers make use of local information about traffic conditions to either reject or accept information packets from their neighbors. We show that when nodes are only aware of their own congestion state they self-organize into a hierarchical configuration that delays remarkably the onset of congestion although leading to a sharp first-order-like congestion transition. We also consider the case when nodes are aware of the congestion state of their neighbors. In this case, we show that empathy between nodes is strongly beneficial to the overall performance of the system and it is possible to achieve larger values for the critical load together with a smooth, second-order-like, transition. Finally, we show how local empathy minimize the impact of congestion as much as global minimization. Therefore, here we present an outstanding example of how local dynamical rules can optimize the system’s functioning up to the levels reached using global knowledge.

Round-Trip Delay Estimation in OPC UA Server-Client Communication Channel

OpenAIRE

Nakutis, Zilvinas; Deksnys, Vytautas; Jarusevicius, Ignas; Dambrauskas, Vilius; Cincikas, Gediminas; Kriauceliunas, Alenas

2017-01-01

In this paper an estimation of round-trip delay (RTD) in OPC UA server-client channel was investigated in various data communication networks including Ethernet, WiFi, and 3G. Testing was carried out using the developed IoT gateway device running OPC UA server and remote computer running OPC UA client. The server and the client machines were configured to operate in Virtual Private Network powered by OpenVPN. Experimental analysis revealed that RTD values are distributed in the wide range exh...

Meaning Making Through Minimal Linguistic Forms in Computer-Mediated Communication

Directory of Open Access Journals (Sweden)

Muhammad Shaban Rafi

2014-05-01

Full Text Available The purpose of this study was to investigate the linguistic forms, which commonly constitute meanings in the digital environment. The data were sampled from 200 Bachelor of Science (BS students (who had Urdu as their primary language of communication and English as one of the academic languages or the most prestigious second language of five universities situated in Lahore, Pakistan. The procedure for analysis was conceived within much related theoretical work on text analysis. The study reveals that cyber-language is organized through patterns of use, which can be broadly classified into minimal linguistic forms constituting a meaning-making resource. In addition, the expression of syntactic mood, and discourse roles the participants technically assume tend to contribute to the theory of meaning in the digital environment. It is hoped that the study would make some contribution to the growing literature on multilingual computer-mediated communication (CMC.

The relationship of early communication concerns to developmental delay and symptoms of autism spectrum disorders.

Science.gov (United States)

Turygin, Nicole; Matson, Johnny L; Konst, Matthew; Williams, Lindsey

2013-08-01

Parental concerns related to communication are an oft-cited reason that children present to early intervention clinics. We examine the relationship between early communication first concerns (FCs) and symptoms of ASD. The present study included 3173 toddlers at risk for developmental delay. The Battelle Developmental Inventory, 2nd edition and the Baby and Infant Screen for Children with aUtIsm Traits (BISCUIT) were used to examine developmental quotient scores and autism symptoms. Significant results were observed with respect to FC group and gender. A significant effect of FC-Communication group was observed with respect to developmental quotient overall and subscale scores, as well as autism symptom scores. Those with communication disorders are a heterogeneous population and do not account for all children who will meet criteria for a diagnosis of an ASD.

Synchronization of delayed systems in the presence of delay time modulation

International Nuclear Information System (INIS)

Kye, Won-Ho; Choi, Muhan; Kim, Myung-Woon; Lee, Soo-Young; Rim, Sunghwan; Kim, Chil-Min; Park, Young-Jai

2004-01-01

We investigate synchronization in the presence of delay time modulation for application to communication. We have observed that the robust synchronization is established by a common delay signal and its threshold is presented using Lyapunov exponents analysis. The influence of the delay time modulation in chaotic oscillators is also discussed

Event-Triggered Control for Multiagent Systems with the Problem of Packet Losses and Communication Delays When Using the Second-Order Neighbors’ Information

Directory of Open Access Journals (Sweden)

Chuan Yan

2014-01-01

Full Text Available This paper mainly investigates the event-triggered control for discrete-time multiagent systems with the problem of packet losses and communication delays when both the first-order and the second-order neighbors’ information are used. Event-triggered control laws are adopted so as to reduce the frequency of individual actuation updating under the sampled-data framework for discrete-time agent dynamics. The communication graph is undirected and the loss of data across each communication link occurs at certain probability, which is governed by a Bernoulli process. It is found that the distributed consensus speeds up by using the second-order neighbors’ information when packet losses and communication delays occur. Numerical examples are given to demonstrate the effectiveness of the proposed methods.

Parents' Adoption of Social Communication Intervention Strategies: Families Including Children with Autism Spectrum Disorder Who Are Minimally Verbal

Science.gov (United States)

Shire, Stephanie Y.; Goods, Kelly; Shih, Wendy; Distefano, Charlotte; Kaiser, Ann; Wright, Courtney; Mathy, Pamela; Landa, Rebecca; Kasari, Connie

2015-01-01

Notably absent from the intervention literature are parent training programs targeting school-aged children with autism who have limited communication skills (Tager-Flusberg and Kasari in "Autism Res" 6:468-478, 2013). Sixty-one children with autism age 5-8 with minimal spontaneous communication received a 6-month social communication…

Delay reduction in multi-hop device-to-device communication using network coding

KAUST Repository

Douik, Ahmed S.

2015-08-12

This paper considers the problem of reducing the broadcast delay of wireless networks using instantly decodable network coding (IDNC) based device-to-device (D2D) communications. In D2D-enabled networks, devices help hasten the recovery of the lost packets of devices in their transmission range by sending network coded packets. To solve the problem, the different events occurring at each device are identified so as to derive an expression for the probability distribution of the decoding delay. The joint optimization problem over the set of transmitting devices and the packet combinations of each is formulated. Due to the high complexity of finding the optimal solution, this paper focuses on cooperation without interference between the transmitting users. The optimal solution, in such interference-less scenario, is expressed using a graph theory approach by introducing the cooperation graph. Extensive simulations compare the decoding delay experienced in the Point to Multi-Point (PMP), the fully connected D2D (FC-D2D) and the more practical partially connected D2D (PC-D2D) configurations and suggest that the PC-D2D outperforms the FC-D2D in all situations and provides an enormous gain for poorly connected networks.

Synchronization of conference presentation sequence using delay equalization approach

Science.gov (United States)

Godavari, Rakesh K.; Celenk, Mehmet

2001-11-01

In this paper, a delay equalization approach is proposed for cohesive conference presentation with minimal screen- freezing effect. The underlying screen-freezing effect is due to varying delays in the communication channels involved in broadcasting. In turn, this poses a threat to the goal of uniform delay distribution among data packets for synchronized presentation broadcast. We wish to achieve uniformity among packet arrival times to the recipients. This objective is achieved by transforming a given input delay distribution (D) to the desired output density through a delay equalization process. Considering a general case of between packet and frame delay distributions for a given input, the desired output is obtained through a delay equalization process. In case of a specific normal delay distribution, a memory-less system g(D) is determined as an approximation to the delay equalizer such that the equalizer output O(t)equalsg[D(t)] is uniformly distributed in the allowable delay limits of (a,b) assuring the specified quality of service (QoS) parameters. The corresponding delay is added at each recipient workstation, which acts as the wait period required before it begins its designated presentation.For a zero mean normal delay density case, the equalizer transfer function can be given in a closed from solution as O(t)equalsg[D(t)[equals(b-a)]0.5+eft(-D/$RO OTR(0)))[+a, where erf(x) is the standard error function. The histogram approximation is adopted as an asymptotically delay equalization means for general cases. This technique provides a means for modifying the dynamic range of data acquired by altering it into a desired distribution. In experimentation, equalizer characteristic functions are derived for a set of selected input delays to obtain the desired output. The delay equalizer system developed here is suited for deployment in a distributed hierarchical conferencing environment. To accommodate a broadcast continuity, the multimedia presentation is

The use of cell phones and radio communication systems to reduce delays in getting help for pregnant women in low- and middle-income countries: a scoping review.

Science.gov (United States)

Oyeyemi, Sunday O; Wynn, Rolf

2015-01-01

Delays in getting medical help are important factors in the deaths of many pregnant women and unborn children in the low- and middle-income countries (LMIC). Studies have suggested that the use of cell phones and radio communication systems might reduce such delays. We review the literature regarding the impact of cell phones and radio communication systems on delays in getting medical help by pregnant women in the LMIC. Cochrane Library, PubMed, Maternity and Infant care (Ovid), Web of Science (ISI), and Google Scholar were searched for studies relating to the use of cell phones for maternal and child health services, supplemented with hand searches. We included studies in LMIC and in English involving the simple use of cell phones (or radio communication) to either make calls or send text messages. Fifteen studies met the inclusion criteria. All the studies, while of various designs, demonstrated positive contributory effects of cell phones or radio communication systems in reducing delays experienced by pregnant women in getting medical help. While the results suggested that cell phones could contribute in reducing delays, more studies of a longer duration are needed to strengthen the finding.

The use of cell phones and radio communication systems to reduce delays in getting help for pregnant women in low- and middle-income countries: a scoping review

Directory of Open Access Journals (Sweden)

Sunday O. Oyeyemi

2015-09-01

Full Text Available Background: Delays in getting medical help are important factors in the deaths of many pregnant women and unborn children in the low- and middle-income countries (LMIC. Studies have suggested that the use of cell phones and radio communication systems might reduce such delays. Objectives: We review the literature regarding the impact of cell phones and radio communication systems on delays in getting medical help by pregnant women in the LMIC. Design: Cochrane Library, PubMed, Maternity and Infant care (Ovid, Web of Science (ISI, and Google Scholar were searched for studies relating to the use of cell phones for maternal and child health services, supplemented with hand searches. We included studies in LMIC and in English involving the simple use of cell phones (or radio communication to either make calls or send text messages. Results: Fifteen studies met the inclusion criteria. All the studies, while of various designs, demonstrated positive contributory effects of cell phones or radio communication systems in reducing delays experienced by pregnant women in getting medical help. Conclusions: While the results suggested that cell phones could contribute in reducing delays, more studies of a longer duration are needed to strengthen the finding.

Performance Analysis of Mobile Ad Hoc Unmanned Aerial Vehicle Communication Networks with Directional Antennas

Directory of Open Access Journals (Sweden)

Abdel Ilah Alshbatat

2010-01-01

Full Text Available Unmanned aerial vehicles (UAVs have the potential of creating an ad hoc communication network in the air. Most UAVs used in communication networks are equipped with wireless transceivers using omnidirectional antennas. In this paper, we consider a collection of UAVs that communicate through wireless links as a mobile ad-hoc network using directional antennas. The network design goal is to maximize the throughput and minimize the end-to-end delay. In this respect, we propose a new medium access control protocol for a network of UAVs with directional antennas. We analyze the communication channel between the UAVs and the effect of aircraft attitude on the network performance. Using the optimized network engineering tool (OPNET, we compare our protocol with the IEEE 802.11 protocol for omnidirectional antennas. The simulation results show performance improvement in end-to-end delay as well as throughput.

Group Delay of High Q Antennas

DEFF Research Database (Denmark)

Bahramzy, Pevand; Pedersen, Gert Frølund

2013-01-01

Group Delay variations versus frequency is an essential factor which can cause distortion and degradation in the signals. Usually this is an issue in wideband communication systems, such as satellite communication systems, which are used for transmitting wideband data. However, group delay can also...... become an issue, when working with high Q antennas, because of the steep phase shift over the frequency. In this paper, it is measured how large group delay variations can become, when going from a low Q antenna to a high Q antenna. The group delay of a low Q antenna is shown to be around 1.3 ns, whereas...... a high Q antenna has group delay of around 22 ns. It is due to this huge group delay variation characteristics of high Q antennas, that signal distortion might occur in the radio system with high Q antennas....

Personal communications via ACTS satellite HBR transponders

Science.gov (United States)

Fang, Russell J. F.

1991-01-01

The concept of a fully meshed network of briefcase-sized terminals is presented for personal communications over Ka-band satellite transponders. In this concept, undesirable double-hop delays are avoided for voice communications. The bandwidth and power resources of the transponder are efficiently shared by users in a simple demand-assigned manner via code-division multiple access (CDMA). Voice, data, and facsimile are statistically multiplexed at each terminal. In order to minimize terminal costs, frequency-precorrected, and level-preadjusted continuous-wave tones are sent from the central network control station in each beam so that the terminals in each down-link beam can use these pilots as references for antenna acquisition and tracking, as reliable frequency sources, and as indicators of signal fade for up-link power control (ULPC). The potential CDMA 'near-far' problem due to up-link fades is mitigated by using ULPC. Quasi-burst mode transmission is employed to minimize the potential clock and pseudorandom number code synchronization.

Delayed Ejaculation

Science.gov (United States)

... cases, it is due to a combination of physical and psychological concerns. Psychological causes of delayed ejaculation include: Depression, anxiety or other mental health conditions Relationship problems due to stress, poor communication ...

Some Protocols For Optical-Fiber Digital Communications

Science.gov (United States)

Yeh, Cavour; Gerla, Mario

1989-01-01

One works best in heavy traffic, another, in light traffic. Three protocols proposed for digital communications among stations connected by passive taps to pair of uni-directional optical-fiber buses. Mediate round-robin, bounded-delay access to buses by all stations and particularly suited to fast transmission. Partly because transmission medium passive (no relay stations) and partly because protocols distribute control of network among all stations with provision for addition and deletion of stations (no control stations), communication network able to resist and recover from failures. Implicit token propagates in one direction on one bus and in opposite direction on other bus, minimizing interval of silence between end of one round and beginning of next.

Impulsive control of time-delay systems using delayed impulse and its application to impulsive master-slave synchronization

International Nuclear Information System (INIS)

Sun Jitao; Han Qinglong; Jiang Xiefu

2008-01-01

This Letter is concerned with impulsive control of a class of nonlinear time-delay systems. Some uniform stability criteria for the closed-loop time-delay system under delayed impulsive control are derived by using piecewise Lyapunov functions. Then the criteria are applied to impulsive master-slave synchronization of some secure communication systems with transmission delays and sample delays under delayed impulsive control. Two numerical examples are given to illustrate the effectiveness of the derived results

A Cooperative Traffic Control of Vehicle–Intersection (CTCVI) for the Reduction of Traffic Delays and Fuel Consumption

Science.gov (United States)

Li, Jinjian; Dridi, Mahjoub; El-Moudni, Abdellah

2016-01-01

The problem of reducing traffic delays and decreasing fuel consumption simultaneously in a network of intersections without traffic lights is solved by a cooperative traffic control algorithm, where the cooperation is executed based on the connection of Vehicle-to-Infrastructure (V2I). This resolution of the problem contains two main steps. The first step concerns the itinerary of which intersections are chosen by vehicles to arrive at their destination from their starting point. Based on the principle of minimal travel distance, each vehicle chooses its itinerary dynamically based on the traffic loads in the adjacent intersections. The second step is related to the following proposed cooperative procedures to allow vehicles to pass through each intersection rapidly and economically: on one hand, according to the real-time information sent by vehicles via V2I in the edge of the communication zone, each intersection applies Dynamic Programming (DP) to cooperatively optimize the vehicle passing sequence with minimal traffic delays so that the vehicles may rapidly pass the intersection under the relevant safety constraints; on the other hand, after receiving this sequence, each vehicle finds the optimal speed profiles with the minimal fuel consumption by an exhaustive search. The simulation results reveal that the proposed algorithm can significantly reduce both travel delays and fuel consumption compared with other papers under different traffic volumes. PMID:27999333

A Cooperative Traffic Control of Vehicle–Intersection (CTCVI for the Reduction of Traffic Delays and Fuel Consumption

Directory of Open Access Journals (Sweden)

Jinjian Li

2016-12-01

Full Text Available The problem of reducing traffic delays and decreasing fuel consumption simultaneously in a network of intersections without traffic lights is solved by a cooperative traffic control algorithm, where the cooperation is executed based on the connection of Vehicle-to-Infrastructure (V2I. This resolution of the problem contains two main steps. The first step concerns the itinerary of which intersections are chosen by vehicles to arrive at their destination from their starting point. Based on the principle of minimal travel distance, each vehicle chooses its itinerary dynamically based on the traffic loads in the adjacent intersections. The second step is related to the following proposed cooperative procedures to allow vehicles to pass through each intersection rapidly and economically: on one hand, according to the real-time information sent by vehicles via V2I in the edge of the communication zone, each intersection applies Dynamic Programming (DP to cooperatively optimize the vehicle passing sequence with minimal traffic delays so that the vehicles may rapidly pass the intersection under the relevant safety constraints; on the other hand, after receiving this sequence, each vehicle finds the optimal speed profiles with the minimal fuel consumption by an exhaustive search. The simulation results reveal that the proposed algorithm can significantly reduce both travel delays and fuel consumption compared with other papers under different traffic volumes.

Transmission delays in hardware clock synchronization

Science.gov (United States)

Shin, Kang G.; Ramanathan, P.

1988-01-01

Various methods, both with software and hardware, have been proposed to synchronize a set of physical clocks in a system. Software methods are very flexible and economical but suffer an excessive time overhead, whereas hardware methods require no time overhead but are unable to handle transmission delays in clock signals. The effects of nonzero transmission delays in synchronization have been studied extensively in the communication area in the absence of malicious or Byzantine faults. The authors show that it is easy to incorporate the ideas from the communication area into the existing hardware clock synchronization algorithms to take into account the presence of both malicious faults and nonzero transmission delays.

Clinical application of minimizing picture archiving and communication system

International Nuclear Information System (INIS)

Chen Lixin; Zhao Weijiang; Jin Qiongying; Gu Wenxiang; Yuan Quan

2003-01-01

Objective: To investigate the use of the minimizing picture archiving and communication system (mini-PACS) in practical work and to realize the advent of filmless radiology. Methods: A PC-based ethernet was set up. The medical imaging equipments including CT, MR, digital fluoroscopy, DSA, and a laser camera were combined with the ethernet, and the digital imaging network (DIN) was integrated with the medical diagnostic imaging system (MDIS). In this way, the radiology information system (RIS) was established. Through one of the PC workstations with a double network card, this RIS was connected to the hospital information system (HIS). Results: The mini-PACS has been repeatedly used for more than 2 years. The system in Radiology department has been established and improved. With the present digital imaging system, such functions as the acquiring, storing, transmitting, printing, and browsing of digital images have been put into practice, all in accordance with the manners of the digital imaging communication in medicine 3.0 (DICOM 3.0). Digital imaging and diagnostic reports were managed through Microsoft Access database. Images may be kept on line in different kinds of equipment for 3-6 months. All images have been recorded on CD-R disks, so as to be kept off line permanently. So far, over 32700 reports have been stored in the database. From mini-PACS HIS terminals images and diagnostic information may be acquired on a limited scale. Conclusion: mini-PACS needs only a low cost of investment and operation. Its maintenance is simple and its performance is efficient. The main functions of the PACS can mostly be achieved. There lies a bright prospect for its use in small and medium hospitals

Maternal postpartum depressive symptoms predict delay in non-verbal communication in 14-month-old infants.

Science.gov (United States)

Kawai, Emiko; Takagai, Shu; Takei, Nori; Itoh, Hiroaki; Kanayama, Naohiro; Tsuchiya, Kenji J

2017-02-01

We investigated the potential relationship between maternal depressive symptoms during the postpartum period and non-verbal communication skills of infants at 14 months of age in a birth cohort study of 951 infants and assessed what factors may influence this association. Maternal depressive symptoms were measured using the Edinburgh Postnatal Depression Scale, and non-verbal communication skills were measured using the MacArthur-Bates Communicative Development Inventories, which include Early Gestures and Later Gestures domains. Infants whose mothers had a high level of depressive symptoms (13+ points) during both the first month postpartum and at 10 weeks were approximately 0.5 standard deviations below normal in Early Gestures scores and 0.5-0.7 standard deviations below normal in Later Gestures scores. These associations were independent of potential explanations, such as maternal depression/anxiety prior to birth, breastfeeding practices, and recent depressive symptoms among mothers. These findings indicate that infants whose mothers have postpartum depressive symptoms may be at increased risk of experiencing delay in non-verbal development. Copyright © 2016 Elsevier Inc. All rights reserved.

Development of an Android OS Based Controller of a Double Motor Propulsion System for Connected Electric Vehicles and Communication Delays Analysis

Directory of Open Access Journals (Sweden)

Pedro Daniel Urbina Coronado

2015-01-01

Full Text Available Developments of technologies that facilitate vehicle connectivity represent a market demand. In particular, mobile device (MD technology provides advanced user interface, customization, and upgradability characteristics that can facilitate connectivity and possibly aid in the goal of autonomous driving. This work explores the use of a MD in the control system of a conceptual electric vehicle (EV. While the use of MD for real-time control and monitoring has been reported, proper consideration has not been given to delays in data flow and their effects on system performance. The motor of a novel propulsion system for an EV was conditioned to be controlled in a wireless local area network by an ecosystem that includes a MD and an electronic board. An intended accelerator signal is predefined and sent to the motor and rotational speed values produced in the motor are sent back to the MD. Sample periods in which the communication really occurs are registered. Delays in the sample periods and produced errors in the accelerator and rotational speed signals are presented and analyzed. Maximum delays found in communications were of 0.2 s, while the maximum error produced in the accelerator signal was of 3.54%. Delays are also simulated, with a response that is similar to the behavior observed in the experiments.

Sliding mode control for synchronization of Roessler systems with time delays and its application to secure communication

International Nuclear Information System (INIS)

Chen, C-K; Yan, J-J; Liao, T-L

2007-01-01

This study is concerned with the chaos synchronization problem of Roessler systems subjected to multiple time delays. Based on the sliding mode control (SMC) technique, we first propose an adaptive switching surface which does not allow for a reduction of system order, as is the case in most SMC schemes. Then both a sliding mode controller and a new sufficient condition are derived to guarantee, respectively, the global hitting of the sliding mode and stability of the equivalent error dynamics in the sliding mode. Thus, the chaos synchronization for Roessler systems with multiple time delays can surely be achieved. Moreover, the proposed scheme is then applied to the secure communication system. Numerical simulations are included to demonstrate the feasibility of the proposed scheme

Teaching a Child with Autism and Severe Language Delays to Reject: Direct and Indirect Effects of Functional Communication Training

Science.gov (United States)

Martin, Christian A.; Drasgow, Erik; Halle, James W.; Brucker, Jennifer M.

2005-01-01

We used functional communication training to teach Bob, a 10-year-old student with autism and severe language delays, to reject items by touching an icon. Our initial assessment revealed that Bob's behaviours serving a rejecting function consisted of pushing away, yelling, bear hugging-grabbing, and leaving. We used prompting, differential…

Simulation of activation and propagation delay during tripolar neural stimulation

NARCIS (Netherlands)

Goodall, E.V.; Goodall, Eleanor V.; Kosterman, L. Martin; Struijk, Johannes J.; Struijk, J.J.; Holsheimer, J.

1993-01-01

Computer simulations were perfonned to investigate the influence of stimulus amplitude on cathodal activation delay, propagation delay and blocking during stimulation with a bipolar cuff electrode. Activation and propagation delays were combined in a total delay term which was minimized between the

Radio resource allocation over fading channels under statistical delay constraints

CERN Document Server

Le-Ngoc, Tho

2017-01-01

This SpringerBrief presents radio resource allocation schemes for buffer-aided communications systems over fading channels under statistical delay constraints in terms of upper-bounded average delay or delay-outage probability. This Brief starts by considering a source-destination communications link with data arriving at the source transmission buffer. The first scenario, the joint optimal data admission control and power allocation problem for throughput maximization is considered, where the source is assumed to have a maximum power and an average delay constraints. The second scenario, optimal power allocation problems for energy harvesting (EH) communications systems under average delay or delay-outage constraints are explored, where the EH source harvests random amounts of energy from renewable energy sources, and stores the harvested energy in a battery during data transmission. Online resource allocation algorithms are developed when the statistical knowledge of the random channel fading, data arrivals...

MAC layer power management schemes for efficient energy- delay tradeoffs in wireless local area networks

OpenAIRE

Sarkar, Mahasweta

2006-01-01

In order to minimize power consumption and thereby prolong the system lifetime of battery powered wireless devices, it makes sense for such devices to transit to a very low power "Sleep" state when they are not communicating with their peers. However the main challenge of the sleep mechanism lies in the wireless nodes inability to "wake up" as soon as a packet arrives for it during its sleep state. This leads to an obvious tradeoff between power saving and packet delay. In this dissertation w...

Minimal Coleman-Weinberg theory explains the diphoton excess

DEFF Research Database (Denmark)

Antipin, Oleg; Mojaza, Matin; Sannino, Francesco

2016-01-01

It is possible to delay the hierarchy problem, by replacing the standard Higgs-sector by the Coleman-Weinberg mechanism, and at the same time ensure perturbative naturalness through the so-called Veltman conditions. As we showed in a previous study, minimal models of this type require the introdu......It is possible to delay the hierarchy problem, by replacing the standard Higgs-sector by the Coleman-Weinberg mechanism, and at the same time ensure perturbative naturalness through the so-called Veltman conditions. As we showed in a previous study, minimal models of this type require...

A Prospective Randomized Study on Operative Treatment for Simple Distal Tibial Fractures-Minimally Invasive Plate Osteosynthesis Versus Minimal Open Reduction and Internal Fixation.

Science.gov (United States)

Kim, Ji Wan; Kim, Hyun Uk; Oh, Chang-Wug; Kim, Joon-Woo; Park, Ki Chul

2018-01-01

To compare the radiologic and clinical results of minimally invasive plate osteosynthesis (MIPO) and minimal open reduction and internal fixation (ORIF) for simple distal tibial fractures. Randomized prospective study. Three level 1 trauma centers. Fifty-eight patients with simple and distal tibial fractures were randomized into a MIPO group (treatment with MIPO; n = 29) or a minimal group (treatment with minimal ORIF; n = 29). These numbers were designed to define the rate of soft tissue complication; therefore, validation of superiority in union time or determination of differences in rates of delayed union was limited in this study. Simple distal tibial fractures treated with MIPO or minimal ORIF. The clinical outcome measurements included operative time, radiation exposure time, and soft tissue complications. To evaluate a patient's function, the American Orthopedic Foot and Ankle Society ankle score (AOFAS) was used. Radiologic measurements included fracture alignment, delayed union, and union time. All patients acquired bone union without any secondary intervention. The mean union time was 17.4 weeks and 16.3 weeks in the MIPO and minimal groups, respectively. There was 1 case of delayed union and 1 case of superficial infection in each group. The radiation exposure time was shorter in the minimal group than in the MIPO group. Coronal angulation showed a difference between both groups. The American Orthopedic Foot and Ankle Society ankle scores were 86.0 and 86.7 in the MIPO and minimal groups, respectively. Minimal ORIF resulted in similar outcomes, with no increased rate of soft tissue problems compared to MIPO. Both MIPO and minimal ORIF have high union rates and good functional outcomes for simple distal tibial fractures. Minimal ORIF did not result in increased rates of infection and wound dehiscence. Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Analysis of Time Delay Simulation in Networked Control System

OpenAIRE

Nyan Phyo Aung; Zaw Min Naing; Hla Myo Tun

2016-01-01

The paper presents a PD controller for the Networked Control Systems (NCS) with delay. The major challenges in this networked control system (NCS) are the delay of the data transmission throughout the communication network. The comparative performance analysis is carried out for different delays network medium. In this paper, simulation is carried out on Ac servo motor control system using CAN Bus as communication network medium. The True Time toolbox of MATLAB is used for simulation to analy...

Information transfer via implicit encoding with delay time modulation in a time-delay system

Energy Technology Data Exchange (ETDEWEB)

Kye, Won-Ho, E-mail: whkye@kipo.go.kr [Korean Intellectual Property Office, Government Complex Daejeon Building 4, 189, Cheongsa-ro, Seo-gu, Daejeon 302-701 (Korea, Republic of)

2012-08-20

A new encoding scheme for information transfer with modulated delay time in a time-delay system is proposed. In the scheme, the message is implicitly encoded into the modulated delay time. The information transfer rate as a function of encoding redundancy in various noise scales is presented and it is analyzed that the implicit encoding scheme (IES) has stronger resistance against channel noise than the explicit encoding scheme (EES). In addition, its advantages in terms of secure communication and feasible applications are discussed. -- Highlights: ► We propose new encoding scheme with delay time modulation. ► The message is implicitly encoded with modulated delay time. ► The proposed scheme shows stronger resistance against channel noise.

Emergency Communication

Science.gov (United States)

: Environmental Documents, Reports LANL Home Calendar Search Contacts Resources » Emergency Communication Emergency Communication Stay informed of emergencies, weather delays, closures, other alerts. Find links to

Delayed Consensus Problem for Single and Double Integrator Systems

Directory of Open Access Journals (Sweden)

Martín Velasco-Villa

2015-01-01

Full Text Available This work deals with the analysis of the consensus problem for networks of agents constituted by single and double integrator systems. It is assumed that the communication among agents is affected by a constant time-delay. Previous and numerous analysis of the problem shows that the maximum communication time-delay that can be introduced to the network without affecting the consensus of the group of the agents depends on the considered topology. In this work, a control scheme that is based on the estimation of future states of the agents and that allows increasing the magnitude of a possible time-delay affecting the communication channels is proposed. How the proposed delay compensation strategy is independent of the network topology in the sense that the maximum allowable time-delay that could be supported by the network depends on a design parameter and not on the maximum eigenvalue of the corresponding Laplacian matrix is shown. It is formally proven that, under the proposed prediction scheme, the consensus of the group can be achieved by improving the maximum time-delay bounds previously reported in the literature. Numerical simulations show the effectiveness of the proposed solution.

Delay tolerant networks

CERN Document Server

Gao, Longxiang; Luan, Tom H

2015-01-01

This brief presents emerging and promising communication methods for network reliability via delay tolerant networks (DTNs). Different from traditional networks, DTNs possess unique features, such as long latency and unstable network topology. As a result, DTNs can be widely applied to critical applications, such as space communications, disaster rescue, and battlefield communications. The brief provides a complete investigation of DTNs and their current applications, from an overview to the latest development in the area. The core issue of data forward in DTNs is tackled, including the importance of social characteristics, which is an essential feature if the mobile devices are used for human communication. Security and privacy issues in DTNs are discussed, and future work is also discussed.

A Robust Longitudinal Control Strategy of Platoons under Model Uncertainties and Time Delays

Directory of Open Access Journals (Sweden)

Na Chen

2018-01-01

Full Text Available Automated vehicles are designed to free drivers from driving tasks and are expected to improve traffic safety and efficiency when connected via vehicle-to-vehicle communication, that is, connected automated vehicles (CAVs. The time delays and model uncertainties in vehicle control systems pose challenges for automated driving in real world. Ignoring them may render the performance of cooperative driving systems unsatisfactory or even unstable. This paper aims to design a robust and flexible platooning control strategy for CAVs. A centralized control method is presented, where the leader of a CAV platoon collects information from followers, computes the desired accelerations of all controlled vehicles, and broadcasts the desired accelerations to followers. The robust platooning is formulated as a Min-Max Model Predictive Control (MM-MPC problem, where optimal accelerations are generated to minimize the cost function under the worst case, where the worst case is taken over the possible models. The proposed method is flexible in such a way that it can be applied to both homogeneous platoon and heterogeneous platoon with mixed human-driven and automated controlled vehicles. A third-order linear vehicle model with fixed feedback delay and stochastic actuator lag is used to predict the platoon behavior. Actuator lag is assumed to vary randomly with unknown distributions but a known upper bound. The controller regulates platoon accelerations over a time horizon to minimize a cost function representing driving safety, efficiency, and ride comfort, subject to speed limits, plausible acceleration range, and minimal net spacing. The designed strategy is tested by simulating homogeneous and heterogeneous platoons in a number of typical and extreme scenarios to assess the system stability and performance. The test results demonstrate that the designed control strategy for CAV can ensure the robustness of stability and performance against model uncertainties

Self-Adaptive Context Aware Routing Protocol for Unicast Communication in Delay and Tolerant Network

Directory of Open Access Journals (Sweden)

Yunbo Chen

2014-05-01

Full Text Available At present, most of research works in mobile network focus on the network overhead of the known path which exists between the sender and the receiver. However, the trend of the current practical application demands is becoming increasingly distributed and decentralized. The Delay and Tolerant Network (DTN just comes out of such background of the conflicts between them. The DTN could effectively eliminate the gap between the mobile network and the practical application demands. In this paper, a Self-Adaptive Context Aware Routing Protocol (SACARP for the unicast communication in delay and tolerant networks is presented. Meanwhile, according to the real-time context information of DTN, the Kalman filter theory is introduced to predict the information state of mobility for the optional message ferrying node, and then gives the optimal selection strategy of the message ferrying nodes. The simulation experiments have shown that, compared to the familiar single- copy and multi-copy protocols, the SACARP proposed in this paper has better transmission performance and stability, especially when the network is free, the protocol would keep a good performance with fewer connections and less buffer space.

Fiducial marker guided stereotactic liver radiotherapy: Is a time delay between marker implantation and planning CT needed?

DEFF Research Database (Denmark)

Worm, Esben S; Bertholet, Jenny; Høyer, Morten

2016-01-01

To minimize the risk of marker migration in fiducial marker guided liver SBRT it is common to add a delay of a week between marker implantation and planning CT. This study found that such a delay is unnecessary and could be avoided to minimize the treatment preparation time.......To minimize the risk of marker migration in fiducial marker guided liver SBRT it is common to add a delay of a week between marker implantation and planning CT. This study found that such a delay is unnecessary and could be avoided to minimize the treatment preparation time....

Autonomous Congestion Control in Delay-Tolerant Networks

Science.gov (United States)

Burleigh, Scott; Jennings, Esther; Schoolcraft, Joshua

2006-01-01

This presentation highlights communication congestion control in delay-tolerant networks (DTNs). Large-scale future space exploration will offer complex communication challenges that may be best addressed by establishing a network infrastructure. However, current internet techniques for congestion control are not well suited for operation of a network over interplanetary distances. An alternative, delay-tolerant technique for congestion control in a delay-tolerant network is presented. A simple DTN was constructed and an experimental congestion control mechanism was applied. The mechanism appeared to be effective and each router was able to make its bundle acceptance decisions autonomously. Future research will examine more complex topologies and alternative bundle acceptance rules that might enhance performance.

Heterogeneous Cellular Networks with Spatio-Temporal Traffic: Delay Analysis and Scheduling

OpenAIRE

Zhong, Yi; Quek, Tony Q. S.; Ge, Xiaohu

2016-01-01

Emergence of new types of services has led to various traffic and diverse delay requirements in fifth generation (5G) wireless networks. Meeting diverse delay requirements is one of the most critical goals for the design of 5G wireless networks. Though the delay of point-to-point communications has been well investigated, the delay of multi-point to multi-point communications has not been thoroughly studied since it is a complicated function of all links in the network. In this work, we propo...

Parents' Adoption of Social Communication Intervention Strategies: Families Including Children with Autism Spectrum Disorder Who are Minimally Verbal.

Science.gov (United States)

Shire, Stephanie Y; Goods, Kelly; Shih, Wendy; Distefano, Charlotte; Kaiser, Ann; Wright, Courtney; Mathy, Pamela; Landa, Rebecca; Kasari, Connie

2015-06-01

Notably absent from the intervention literature are parent training programs targeting school-aged children with autism who have limited communication skills (Tager-Flusberg and Kasari in Autism Res 6:468-478, 2013). Sixty-one children with autism age 5-8 with minimal spontaneous communication received a 6-month social communication intervention including parent training. Parent-child play interactions were coded for parents' strategy implementation and children's time jointly engaged (Adamson et al. in J Autism Dev Disord 39:84-96, 2009). Parents mastered an average of 70% of the strategies. Further analyses indicated some gains in implementation occurred from mere observation of sessions, while the greatest gains occurred in the first month of active coaching and workshops. Children's joint engagement was associated with parents' implementation success across time demonstrating parents' implementation was relevant to children's social engagement.

Performance Analysis and Evaluation of Advanced Designs for Radio Communication Systems for Communications-Based Train Control (CBTC)

DEFF Research Database (Denmark)

Farooq, Jahanzeb

-consuming process associated with a certain delay. Additionally, these APs are connected to the wayside infrastructure via optical fiber cables that incurs huge costs. To address these problems, a novel design of the CBTC trackside network was proposed at Siemens. In this design, trackside nodes function in ad......Communications-Based Train Control (CBTC) is a modern signalling system that uses radio communication to enable the exchange of high resolution and real-time train control information between the train and the wayside infrastructure. A vast majority of CBTC systems worldwide use IEEE 802.11 Wi......-hoc Wi-Fi mode, which means no associations have to be performed with them prior to transmitting. A train simply broadcasts packets. A node upon receiving these packets forwards them to the next node and so on, forming a chain of nodes. Following this chain, packets arrive at the destination. To minimize...

Padé approximation of delays in cooperative ACC based on string stability requirements

NARCIS (Netherlands)

Xing, H.; Ploeg, J.; Nijmeijer, H.

2016-01-01

Cooperative adaptive cruise control (CACC) improves road throughput by employing intervehicle wireless communications. The inherent communication time delay and vehicle actuator delay significantly limit the minimum intervehicle distance in view of string stability requirements. Hence, controller

A General Algorithm for Robot Formations Using Local Sensing and Minimal Communication

DEFF Research Database (Denmark)

Fredslund, Jakob; Matarić, Maja J

2002-01-01

the friend in the sensor's field of view. We also present a general analytical measure for evaluating formations and apply it to the position data from both simulation and physical robot experiments. We used two lasers to track the physical robots to obtain ground truth validation data....... simulation exper- iments, and 40+ experiments with four physical robots, showing the viability of our approach. The key idea is that each robot keeps a single friend at a desired angle , using some appropriate sensor. By panning the sensor by degrees, the goal for all formations be- comes simply to center......We study the problem of achieving global behavior in a group of distributed robots using only local sensing and minimal communication, in the context of formations. The goal is to have mobile robots establish and maintain some predetermined geo- metric shape. We report results from extensive...

Decentralized Model Predictive Control for Cooperative Multiple Vehicles Subject to Communication Loss

Directory of Open Access Journals (Sweden)

Hojjat A. Izadi

2011-01-01

Full Text Available The decentralized model predictive control (DMPC of multiple cooperative vehicles with the possibility of communication loss/delay is investigated. The neighboring vehicles exchange their predicted trajectories at every sample time to maintain the cooperation objectives. In the event of a communication loss (packet dropout, the most recent available information, which is potentially delayed, is used. Then the communication loss problem changes to a cooperative problem when random large communication delays are present. Such large communication delays can lead to poor cooperation performance and unsafe behaviors such as collisions. A new DMPC approach is developed to improve the cooperation performance and achieve safety in the presence of the large communication delays. The proposed DMPC architecture estimates the tail of neighbor's trajectory which is not available due to the large communication delays for improving the performance. The concept of the tube MPC is also employed to provide the safety of the fleet against collisions, in the presence of large intervehicle communication delays. In this approach, a tube shaped trajectory set is assumed around the trajectory of the neighboring vehicles whose trajectory is delayed/lost. The radius of tube is a function of the communication delay and vehicle's maneuverability (in the absence of model uncertainty. The simulation of formation problem of multiple vehicles is employed to illustrate the effectiveness of the proposed approach.

Evaluation of a School-Based Teen Obesity Prevention Minimal Intervention

Science.gov (United States)

Abood, Doris A.; Black, David R.; Coster, Daniel C.

2008-01-01

Objective: A school-based nutrition education minimal intervention (MI) was evaluated. Design: The design was experimental, with random assignment at the school level. Setting: Seven schools were randomly assigned as experimental, and 7 as delayed-treatment. Participants: The experimental group included 551 teens, and the delayed treatment group…

Study of transmitting electric power utility communications in IP network. Transmission of existing electric power utility communications in best effort type IP network under delay constraint; Denryokuyo tsushin kaisen no IP mo eno shuyo kento. Chien jikan seiyakuka ni okeru best effort gata IP mo eno kison denryokuyo tsushin kaisen no shuyo

Energy Technology Data Exchange (ETDEWEB)

Miyake, H.

2000-07-01

Since IP network does best effort behavior fundamentally, it always generates delay time and delay variation. For this reason, IP network has been unsuitable to transmit real time data such as a voice. However, in recent years, the technologies which transmit real time data in IP network, e.g. VoIP, have spread. If it is possible to transmit the existing electric power utility communications in IP network using these technologies, total network cost can be reduced by the reduction of required bandwidth and the simplification of communication network systems. In this report, it is examined quantitatively whether end-end delay time of the existing electric power utility communications, e.g. on-line, telephone, carrier relay, CDT (cyclic digital transmission equipment), video conference, ITV(industrial television), is within their permission delay time when they are transmitted in the best effort type IP network. (author)

Instantly decodable network coding for real-time device-to-device communications

KAUST Repository

Douik, Ahmed

2016-01-04

This paper studies the delay reduction problem for instantly decodable network coding (IDNC)-based device-to-device (D2D) communication-enabled networks. Unlike conventional point-to-multipoint (PMP) systems in which the wireless base station has the sufficient computation abilities, D2D networks rely on battery-powered operations of the devices. Therefore, a particular emphasis on the computation complexity needs to be addressed in the design of delay reduction algorithms for D2D networks. While most of the existing literature on IDNC directly extend the delay reduction PMP schemes, known to be NP-hard, to the D2D setting, this paper proposes to investigate and minimize the complexity of such algorithms for battery-powered devices. With delay minimization problems in IDNC-based systems being equivalent to a maximum weight clique problems in the IDNC graph, the presented algorithms, in this paper, can be applied to different delay aspects. This paper introduces and focuses on the reduction of the maximum value of the decoding delay as it represents the most general solution. The complexity of the solution is reduced by first proposing efficient methods for the construction, the update, and the dimension reduction of the IDNC graph. The paper, further, shows that, under particular scenarios, the problem boils down to a maximum clique problem. Due to the complexity of discovering such maximum clique, the paper presents a fast selection algorithm. Simulation results illustrate the performance of the proposed schemes and suggest that the proposed fast selection algorithm provides appreciable complexity gain as compared to the optimal selection one, with a negligible degradation in performance. In addition, they indicate that the running time of the proposed solution is close to the random selection algorithm.

Estimation of network path segment delays

Science.gov (United States)

Nichols, Kathleen Marie

2018-05-01

A method for estimation of a network path segment delay includes determining a scaled time stamp for each packet of a plurality of packets by scaling a time stamp for each respective packet to minimize a difference of at least one of a frequency and a frequency drift between a transport protocol clock of a host and a monitoring point. The time stamp for each packet is provided by the transport protocol clock of the host. A corrected time stamp for each packet is determined by removing from the scaled time stamp for each respective packet, a temporal offset between the transport protocol clock and the monitoring clock by minimizing a temporal delay variation of the plurality of packets traversing a segment between the host and the monitoring point.

Minimizing total tardiness in a software developing company

Directory of Open Access Journals (Sweden)

Ícaro Ludwig

2013-03-01

Full Text Available Small companies in service sectors, such as software developers, usually rely on manual-based programming tasks. That programming yields satisfactory results for small task lists, but leads to managerial difficulties as a large number of tasks increases task delays. This paper aims at using scheduling tools to minimize such delays. For that it proposes two heuristics for task scheduling based on the following steps: (i define an initial order for tasks, (ii distribute each task to development teams, and (iii schedule the tasks in each development team aimed at minimizing total tardiness. The proposed approach reduced the total tardiness in simulated in real data, simplified the process of scheduling and provided better tracking of the development process.

STATISTIC MODEL OF DYNAMIC DELAY AND DROPOUT ON CELLULAR DATA NETWORKED CONTROL SYSTEM

Directory of Open Access Journals (Sweden)

MUHAMMAD A. MURTI

2017-07-01

Full Text Available Delay and dropout are important parameters influence overall control performance in Networked Control System (NCS. The goal of this research is to find a model of delay and dropout of data communication link in the NCS. Experiments have been done in this research to a water level control of boiler tank as part of the NCS based on internet communication network using High Speed Packet Access (HSPA cellular technology. By this experiments have been obtained closed-loop system response as well as data delay and dropout of data packets. This research contributes on modeling of the NCS which is combination of controlled plant and data communication link. Another contribution is statistical model of delay and dropout on the NCS.

Proper project planning helps minimize overruns and delays

International Nuclear Information System (INIS)

Donnelly, G.; Cooney, D.J.

1994-01-01

This paper describes planning methods to help minimize cost overruns during the construction of oil and gas pipelines. These steps include background data collection methods, field surveys, determining preliminary pipeline routes, regulatory agency pre-application meetings, and preliminary engineering. Methods for planning also include preliminary aerial mapping, biological assessments, cultural resources investigations, wetlands delineation, geotechnical investigations, and environmental audits. Identification of potential problems can allow for rerouting of the pipeline or remediation processes before they are raised during the permitting process. By coordinating these events from the very beginning, significant cost savings will result that prevent having to rebudget for them after the permitting process starts

Social-Aware Relay Selection for Cooperative Multicast Device-to-Device Communications

Directory of Open Access Journals (Sweden)

Francesco Chiti

2017-12-01

Full Text Available The increasing use of social networks such as Facebook, Twitter, and Instagram to share photos, video streaming, and music among friends has generated a huge increase in the amount of data traffic over wireless networks. This social behavior has triggered new communication paradigms such as device-to-device (D2D and relaying communication schemes, which are both considered as strong drivers for the next fifth-generation (5G cellular systems. Recently, the social-aware layer and its relationship to and influence on the physical communications layer have gained great attention as emerging focus points. We focus here on the case of relaying communications to pursue the multicast data dissemination to a group of users forming a social community through a relay node, according to the extension of the D2D mode to the case of device-to-many devices. Moreover, in our case, the source selects the device to act as the relay among different users of the multicast group by taking into account both the propagation link conditions and the relay social-trust level with the constraint of minimizing the end-to-end content delivery delay. An optimization procedure is also proposed in order to achieve the best performance. Finally, numerical results are provided to highlight the advantages of considering the impact of social level on the end-to-end delivery delay in the integrated social–physical network in comparison with the classical relay-assisted multicast communications for which the relay social-trust level is not considered.

Pain Now or Later: An Outgrowth Account of Pain-Minimization

Science.gov (United States)

Chen, Shuai; Zhao, Dan; Rao, Li-Lin; Liang, Zhu-Yuan; Li, Shu

2015-01-01

The preference for immediate negative events contradicts the minimizing loss principle given that the value of a delayed negative event is discounted by the amount of time it is delayed. However, this preference is understandable if we assume that the value of a future outcome is not restricted to the discounted utility of the outcome per se but is complemented by an anticipated negative utility assigned to an unoffered dimension, which we termed the “outgrowth.” We conducted three studies to establish the existence of the outgrowth and empirically investigated the mechanism underlying the preference for immediate negative outcomes. Study 1 used a content analysis method to examine whether the outgrowth was generated in accompaniment with the delayed negative events. The results revealed that the investigated outgrowth was composed of two elements. The first component is the anticipated negative emotions elicited by the delayed negative event, and the other is the anticipated rumination during the waiting process, in which one cannot stop thinking about the negative event. Study 2 used a follow-up investigation to examine whether people actually experienced the negative emotions they anticipated in a real situation of waiting for a delayed negative event. The results showed that the participants actually experienced a number of negative emotions when waiting for a negative event. Study 3 examined whether the existence of the outgrowth could make the minimizing loss principle work. The results showed that the difference in pain anticipation between the immediate event and the delayed event could significantly predict the timing preference of the negative event. Our findings suggest that people’s preference for experiencing negative events sooner serves to minimize the overall negative utility, which is divided into two parts: the discounted utility of the outcome itself and an anticipated negative utility assigned to the outgrowth. PMID:25747461

Delay-aware adaptive sleep mechanism for green wireless-optical broadband access networks

Science.gov (United States)

Wang, Ruyan; Liang, Alei; Wu, Dapeng; Wu, Dalei

2017-07-01

Wireless-Optical Broadband Access Network (WOBAN) is capacity-high, reliable, flexible, and ubiquitous, as it takes full advantage of the merits from both optical communication and wireless communication technologies. Similar to other access networks, the high energy consumption poses a great challenge for building up WOBANs. To shot this problem, we can make some load-light Optical Network Units (ONUs) sleep to reduce the energy consumption. Such operation, however, causes the increased packet delay. Jointly considering the energy consumption and transmission delay, we propose a delay-aware adaptive sleep mechanism. Specifically, we develop a new analytical method to evaluate the transmission delay and queuing delay over the optical part, instead of adopting M/M/1 queuing model. Meanwhile, we also analyze the access delay and queuing delay of the wireless part. Based on such developed delay models, we mathematically derive ONU's optimal sleep time. In addition, we provide numerous simulation results to show the effectiveness of the proposed mechanism.

BTP: a Block Transfer Protocol for Delay Tolerant Wireless Sensor Networks

DEFF Research Database (Denmark)

Hansen, Morten Tranberg; Biagioni, Edoardo S.

2010-01-01

Wireless sensor networks that are energy-constrained must transmit and receive data as efficiently as possible.  If the transmission is delay tolerant, transferring blocks of accumulated data can be more efficient than transferring each sensed measurement as soon as it is available.  This paper...... proposes a Block Transfer Protocol (BTP) designed for efficient and reliable transmission in wireless sensor networks.  BTP reduces the time it takes to reliably transfer a block of packets compared to conventional link layer protocols, by piggybacking in data packets information about the transfer......, minimizing the number of acknowledgements needed for reliable transmission, and reducing the need for timeouts, which can substantially slow down communication when transmission is unreliable.  In addition, BTP improves reliability by handling false positive acknowledgements and by letting the receivers...

A Conflict-Free Low-Jitter Guaranteed-Rate MAC Protocol for Base-Station Communications in Wireless Mesh Networks

Science.gov (United States)

Szymanski, T. H.

A scheduling algorithm and MAC protocol which provides low-jitter guaranteed-rate (GR) communications between base-stations (BS) in a Wireless Mesh Network (WMN) is proposed. The protocol can provision long-term multimedia services such as VOIP, IPTV, or Video-on-Demand. The time-axis is partitioned into scheduling frames with F time-slots each. A directional antennae scheme is used to provide each directed link with a fixed transmission rate. A protocol such as IntServ is used to provision resources along an end-to-end path of BSs for GR sessions. The Guaranteed Rates between the BSs are then specified in a doubly stochastic traffic rate matrix, which is recursively decomposed to yield a low-jitter GR frame transmission schedule. In the resulting schedule, the end-to-end delay and jitter are small and bounded, and the cell loss rate due to primary scheduling conflicts is zero. For dual-channel WMNs, the MAC protocol can achieve 100% utilization, as well as near-minimal queueing delays and near minimal delay jitter. The scheduling time complexity is O(NFlogNF), where N is the number of BSs. Extensive simulation results are presented.

Diagnostic Delay in Rheumatoid Arthritis

DEFF Research Database (Denmark)

Mølbaek, Karen; Hørslev-Petersen, Kim; Primdahl, Jette

2016-01-01

BACKGROUND: To prevent joint damage among patients with rheumatoid arthritis (RA), there is a need to minimize delays from the onset of symptoms until the initiation of appropriate therapy. The present study explored the factors that have an impact on the time it takes for Danish patients with RA...

Low Delay Video Streaming on the Internet of Things Using Raspberry Pi

Directory of Open Access Journals (Sweden)

Ulf Jennehag

2016-09-01

Full Text Available The Internet of Things is predicted to consist of over 50 billion devices aiming to solve problems in most areas of our digital society. A large part of the data communicated is expected to consist of various multimedia contents, such as live audio and video. This article presents a solution for the communication of high definition video in low-delay scenarios (<200 ms under the constraints of devices with limited hardware resources, such as the Raspberry Pi. We verify that it is possible to enable low delay video streaming between Raspberry Pi devices using a distributed Internet of Things system called the SensibleThings platform. Specifically, our implementation transfers a 6 Mbps H.264 video stream of 1280 × 720 pixels at 25 frames per second between devices with a total delay of 181 ms on the public Internet, of which the overhead of the distributed Internet of Things communication platform only accounts for 18 ms of this delay. We have found that the most significant bottleneck of video transfer on limited Internet of Things devices is the video coding and not the distributed communication platform, since the video coding accounts for 90% of the total delay.

Delay Bound: Fractal Traffic Passes through Network Servers

Directory of Open Access Journals (Sweden)

Ming Li

2013-01-01

Full Text Available Delay analysis plays a role in real-time systems in computer communication networks. This paper gives our results in the aspect of delay analysis of fractal traffic passing through servers. There are three contributions presented in this paper. First, we will explain the reasons why conventional theory of queuing systems ceases in the general sense when arrival traffic is fractal. Then, we will propose a concise method of delay computation for hard real-time systems as shown in this paper. Finally, the delay computation of fractal traffic passing through severs is presented.

Power Minimization through Packet Retention in Cognitive Radio Sensor Networks under Interference and Delay Constraints: An Optimal Stopping Approach

Directory of Open Access Journals (Sweden)

Amr Y. Elnakeeb

2016-04-01

Full Text Available The aim of this article is twofold: First, we study the problem of packets retention in a queue with the aim of minimizing transmission power in delay-tolerant applications. The problem is classified as an optimal stopping problem. The optimal stopping rule has been derived as well. Optimal number of released packets is determined in each round through an Integer Linear Programming (ILP optimization problem. This transmission paradigm is tested via simulations in an interference-free environment leading to a significant reduction in transmission power (at least 55%. Second, we address the problem of applying the scheme of packets retention through the Optimal Stopping Policy (OSP to underlay Cognitive Radio Sensor Networks (CRSNs where strict interference threshold does exist. Simulations proved that our scheme outperforms traditional transmission method as far as dropped packet rate and Average Power per Transmitted Packet (APTP are concerned.

A Cross-Layer Optimized Opportunistic Routing Scheme for Loss-and-Delay Sensitive WSNs

Science.gov (United States)

Xu, Xin; Yuan, Minjiao; Liu, Xiao; Cai, Zhiping; Wang, Tian

2018-01-01

In wireless sensor networks (WSNs), communication links are typically error-prone and unreliable, so providing reliable and timely data routing for loss- and delay-sensitive applications in WSNs it is a challenge issue. Additionally, with specific thresholds in practical applications, the loss and delay sensitivity implies requirements for high reliability and low delay. Opportunistic Routing (OR) has been well studied in WSNs to improve reliability for error-prone and unreliable wireless communication links where the transmission power is assumed to be identical in the whole network. In this paper, a Cross-layer Optimized Opportunistic Routing (COOR) scheme is proposed to improve the communication link reliability and reduce delay for loss-and-delay sensitive WSNs. The main contribution of the COOR scheme is making full use of the remaining energy in networks to increase the transmission power of most nodes, which will provide a higher communication reliability or further transmission distance. Two optimization strategies referred to as COOR(R) and COOR(P) of the COOR scheme are proposed to improve network performance. In the case of increasing the transmission power, the COOR(R) strategy chooses a node that has a higher communication reliability with same distance in comparison to the traditional opportunistic routing when selecting the next hop candidate node. Since the reliability of data transmission is improved, the delay of the data reaching the sink is reduced by shortening the time of communication between candidate nodes. On the other hand, the COOR(P) strategy prefers a node that has the same communication reliability with longer distance. As a result, network performance can be improved for the following reasons: (a) the delay is reduced as fewer hops are needed while the packet reaches the sink in longer transmission distance circumstances; (b) the reliability can be improved since it is the product of the reliability of every hop of the routing path

A Cross-Layer Optimized Opportunistic Routing Scheme for Loss-and-Delay Sensitive WSNs.

Science.gov (United States)

Xu, Xin; Yuan, Minjiao; Liu, Xiao; Liu, Anfeng; Xiong, Neal N; Cai, Zhiping; Wang, Tian

2018-05-03

In wireless sensor networks (WSNs), communication links are typically error-prone and unreliable, so providing reliable and timely data routing for loss- and delay-sensitive applications in WSNs it is a challenge issue. Additionally, with specific thresholds in practical applications, the loss and delay sensitivity implies requirements for high reliability and low delay. Opportunistic Routing (OR) has been well studied in WSNs to improve reliability for error-prone and unreliable wireless communication links where the transmission power is assumed to be identical in the whole network. In this paper, a Cross-layer Optimized Opportunistic Routing (COOR) scheme is proposed to improve the communication link reliability and reduce delay for loss-and-delay sensitive WSNs. The main contribution of the COOR scheme is making full use of the remaining energy in networks to increase the transmission power of most nodes, which will provide a higher communication reliability or further transmission distance. Two optimization strategies referred to as COOR(R) and COOR(P) of the COOR scheme are proposed to improve network performance. In the case of increasing the transmission power, the COOR(R) strategy chooses a node that has a higher communication reliability with same distance in comparison to the traditional opportunistic routing when selecting the next hop candidate node. Since the reliability of data transmission is improved, the delay of the data reaching the sink is reduced by shortening the time of communication between candidate nodes. On the other hand, the COOR(P) strategy prefers a node that has the same communication reliability with longer distance. As a result, network performance can be improved for the following reasons: (a) the delay is reduced as fewer hops are needed while the packet reaches the sink in longer transmission distance circumstances; (b) the reliability can be improved since it is the product of the reliability of every hop of the routing path

A Cross-Layer Optimized Opportunistic Routing Scheme for Loss-and-Delay Sensitive WSNs

Directory of Open Access Journals (Sweden)

Xin Xu

2018-05-01

Full Text Available In wireless sensor networks (WSNs, communication links are typically error-prone and unreliable, so providing reliable and timely data routing for loss- and delay-sensitive applications in WSNs it is a challenge issue. Additionally, with specific thresholds in practical applications, the loss and delay sensitivity implies requirements for high reliability and low delay. Opportunistic Routing (OR has been well studied in WSNs to improve reliability for error-prone and unreliable wireless communication links where the transmission power is assumed to be identical in the whole network. In this paper, a Cross-layer Optimized Opportunistic Routing (COOR scheme is proposed to improve the communication link reliability and reduce delay for loss-and-delay sensitive WSNs. The main contribution of the COOR scheme is making full use of the remaining energy in networks to increase the transmission power of most nodes, which will provide a higher communication reliability or further transmission distance. Two optimization strategies referred to as COOR(R and COOR(P of the COOR scheme are proposed to improve network performance. In the case of increasing the transmission power, the COOR(R strategy chooses a node that has a higher communication reliability with same distance in comparison to the traditional opportunistic routing when selecting the next hop candidate node. Since the reliability of data transmission is improved, the delay of the data reaching the sink is reduced by shortening the time of communication between candidate nodes. On the other hand, the COOR(P strategy prefers a node that has the same communication reliability with longer distance. As a result, network performance can be improved for the following reasons: (a the delay is reduced as fewer hops are needed while the packet reaches the sink in longer transmission distance circumstances; (b the reliability can be improved since it is the product of the reliability of every hop of the

Reducing communication delays and improving quality of care with a tuberculosis laboratory information system in resource poor environments: a cluster randomized controlled trial.

Science.gov (United States)

Blaya, Joaquín A; Shin, Sonya S; Yagui, Martin; Contreras, Carmen; Cegielski, Peter; Yale, Gloria; Suarez, Carmen; Asencios, Luis; Bayona, Jaime; Kim, Jihoon; Fraser, Hamish S F

2014-01-01

Lost, delayed or incorrect laboratory results are associated with delays in initiating treatment. Delays in treatment for Multi-Drug Resistant Tuberculosis (MDR-TB) can worsen patient outcomes and increase transmission. The objective of this study was to evaluate the impact of a laboratory information system in reducing delays and the time for MDR-TB patients to culture convert (stop transmitting). 78 primary Health Centers (HCs) in Lima, Peru. Participants lived within the catchment area of participating HCs and had at least one MDR-TB risk factor. The study design was a cluster randomized controlled trial with baseline data. The intervention was the e-Chasqui web-based laboratory information system. Main outcome measures were: times to communicate a result; to start or change a patient's treatment; and for that patient to culture convert. 1671 patients were enrolled. Intervention HCs took significantly less time to receive drug susceptibility test (DST) (median 11 vs. 17 days, Hazard Ratio 0.67 [0.62-0.72]) and culture (5 vs. 8 days, 0.68 [0.65-0.72]) results. The time to treatment was not significantly different, but patients in intervention HCs took 16 days (20%) less time to culture convert (p = 0.047). The eChasqui system reduced the time to communicate results between laboratories and HCs and time to culture conversion. It is now used in over 259 HCs covering 4.1 million people. This is the first randomized controlled trial of a laboratory information system in a developing country for any disease and the only study worldwide to show clinical impact of such a system. ClinicalTrials.gov NCT01201941.

Neural-adaptive control of single-master-multiple-slaves teleoperation for coordinated multiple mobile manipulators with time-varying communication delays and input uncertainties.

Science.gov (United States)

Li, Zhijun; Su, Chun-Yi

2013-09-01

In this paper, adaptive neural network control is investigated for single-master-multiple-slaves teleoperation in consideration of time delays and input dead-zone uncertainties for multiple mobile manipulators carrying a common object in a cooperative manner. Firstly, concise dynamics of teleoperation systems consisting of a single master robot, multiple coordinated slave robots, and the object are developed in the task space. To handle asymmetric time-varying delays in communication channels and unknown asymmetric input dead zones, the nonlinear dynamics of the teleoperation system are transformed into two subsystems through feedback linearization: local master or slave dynamics including the unknown input dead zones and delayed dynamics for the purpose of synchronization. Then, a model reference neural network control strategy based on linear matrix inequalities (LMI) and adaptive techniques is proposed. The developed control approach ensures that the defined tracking errors converge to zero whereas the coordination internal force errors remain bounded and can be made arbitrarily small. Throughout this paper, stability analysis is performed via explicit Lyapunov techniques under specific LMI conditions. The proposed adaptive neural network control scheme is robust against motion disturbances, parametric uncertainties, time-varying delays, and input dead zones, which is validated by simulation studies.

Towards reporting standards for neuropsychological study results: A proposal to minimize communication errors with standardized qualitative descriptors for normalized test scores.

Science.gov (United States)

Schoenberg, Mike R; Rum, Ruba S

2017-11-01

Rapid, clear and efficient communication of neuropsychological results is essential to benefit patient care. Errors in communication are a lead cause of medical errors; nevertheless, there remains a lack of consistency in how neuropsychological scores are communicated. A major limitation in the communication of neuropsychological results is the inconsistent use of qualitative descriptors for standardized test scores and the use of vague terminology. PubMed search from 1 Jan 2007 to 1 Aug 2016 to identify guidelines or consensus statements for the description and reporting of qualitative terms to communicate neuropsychological test scores was conducted. The review found the use of confusing and overlapping terms to describe various ranges of percentile standardized test scores. In response, we propose a simplified set of qualitative descriptors for normalized test scores (Q-Simple) as a means to reduce errors in communicating test results. The Q-Simple qualitative terms are: 'very superior', 'superior', 'high average', 'average', 'low average', 'borderline' and 'abnormal/impaired'. A case example illustrates the proposed Q-Simple qualitative classification system to communicate neuropsychological results for neurosurgical planning. The Q-Simple qualitative descriptor system is aimed as a means to improve and standardize communication of standardized neuropsychological test scores. Research are needed to further evaluate neuropsychological communication errors. Conveying the clinical implications of neuropsychological results in a manner that minimizes risk for communication errors is a quintessential component of evidence-based practice. Copyright © 2017 Elsevier B.V. All rights reserved.

All-optical delay technique for supporting multiple antennas in a hybrid optical - wireless transmission system

DEFF Research Database (Denmark)

Prince, Kamau; Chiuchiarelli, A; Presi, M

2008-01-01

We introduce a novel continuously-variable optical delay technique to support beam-forming wireless communications systems using antenna arrays. We demonstrate delay with 64-QAM modulated signals at a rate of 15 Msymbol/sec with 2.5 GHz carrier frequency.......We introduce a novel continuously-variable optical delay technique to support beam-forming wireless communications systems using antenna arrays. We demonstrate delay with 64-QAM modulated signals at a rate of 15 Msymbol/sec with 2.5 GHz carrier frequency....

Delay or anticipatory synchronization in one-way coupled systems ...

Indian Academy of Sciences (India)

1Department of Physics, Indian Institute of Science Education and Research, Pune 411 ... Synchronization; variable time delay; time delay systems; secure communication. .... scheme can be defined as y(t − τ2) = x(t − τ1) or y(t) = x(t − τ1 + τ2).

Comparison of two methods for minimizing the effect of delayed charge on the dose delivered with a synchrotron based discrete spot scanning proton beam.

Science.gov (United States)

Whitaker, Thomas J; Beltran, Chris; Tryggestad, Erik; Bues, Martin; Kruse, Jon J; Remmes, Nicholas B; Tasson, Alexandria; Herman, Michael G

2014-08-01

Delayed charge is a small amount of charge that is delivered to the patient after the planned irradiation is halted, which may degrade the quality of the treatment by delivering unwarranted dose to the patient. This study compares two methods for minimizing the effect of delayed charge on the dose delivered with a synchrotron based discrete spot scanning proton beam. The delivery of several treatment plans was simulated by applying a normally distributed value of delayed charge, with a mean of 0.001(SD 0.00025) MU, to each spot. Two correction methods were used to account for the delayed charge. Method one (CM1), which is in active clinical use, accounts for the delayed charge by adjusting the MU of the current spot based on the cumulative MU. Method two (CM2) in addition reduces the planned MU by a predicted value. Every fraction of a treatment was simulated using each method and then recomputed in the treatment planning system. The dose difference between the original plan and the sum of the simulated fractions was evaluated. Both methods were tested in a water phantom with a single beam and simple target geometry. Two separate phantom tests were performed. In one test the dose per fraction was varied from 0.5 to 2 Gy using 25 fractions per plan. In the other test the number fractions were varied from 1 to 25, using 2 Gy per fraction. Three patient plans were used to determine the effect of delayed charge on the delivered dose under realistic clinical conditions. The order of spot delivery using CM1 was investigated by randomly selecting the starting spot for each layer, and by alternating per layer the starting spot from first to last. Only discrete spot scanning was considered in this study. Using the phantom setup and varying the dose per fraction, the maximum dose difference for each plan of 25 fractions was 0.37-0.39 Gy and 0.03-0.05 Gy for CM1 and CM2, respectively. While varying the total number of fractions, the maximum dose difference increased at a rate

Comparison of two methods for minimizing the effect of delayed charge on the dose delivered with a synchrotron based discrete spot scanning proton beam

International Nuclear Information System (INIS)

Whitaker, Thomas J.; Beltran, Chris; Tryggestad, Erik; Kruse, Jon J.; Remmes, Nicholas B.; Tasson, Alexandria; Herman, Michael G.; Bues, Martin

2014-01-01

Purpose: Delayed charge is a small amount of charge that is delivered to the patient after the planned irradiation is halted, which may degrade the quality of the treatment by delivering unwarranted dose to the patient. This study compares two methods for minimizing the effect of delayed charge on the dose delivered with a synchrotron based discrete spot scanning proton beam. Methods: The delivery of several treatment plans was simulated by applying a normally distributed value of delayed charge, with a mean of 0.001(SD 0.00025) MU, to each spot. Two correction methods were used to account for the delayed charge. Method one (CM1), which is in active clinical use, accounts for the delayed charge by adjusting the MU of the current spot based on the cumulative MU. Method two (CM2) in addition reduces the planned MU by a predicted value. Every fraction of a treatment was simulated using each method and then recomputed in the treatment planning system. The dose difference between the original plan and the sum of the simulated fractions was evaluated. Both methods were tested in a water phantom with a single beam and simple target geometry. Two separate phantom tests were performed. In one test the dose per fraction was varied from 0.5 to 2 Gy using 25 fractions per plan. In the other test the number fractions were varied from 1 to 25, using 2 Gy per fraction. Three patient plans were used to determine the effect of delayed charge on the delivered dose under realistic clinical conditions. The order of spot delivery using CM1 was investigated by randomly selecting the starting spot for each layer, and by alternating per layer the starting spot from first to last. Only discrete spot scanning was considered in this study. Results: Using the phantom setup and varying the dose per fraction, the maximum dose difference for each plan of 25 fractions was 0.37–0.39 Gy and 0.03–0.05 Gy for CM1 and CM2, respectively. While varying the total number of fractions, the maximum dose

Minimally conscious state or cortically mediated state?

Science.gov (United States)

Naccache, Lionel

2018-04-01

Durable impairments of consciousness are currently classified in three main neurological categories: comatose state, vegetative state (also recently coined unresponsive wakefulness syndrome) and minimally conscious state. While the introduction of minimally conscious state, in 2002, was a major progress to help clinicians recognize complex non-reflexive behaviours in the absence of functional communication, it raises several problems. The most important issue related to minimally conscious state lies in its criteria: while behavioural definition of minimally conscious state lacks any direct evidence of patient's conscious content or conscious state, it includes the adjective 'conscious'. I discuss this major problem in this review and propose a novel interpretation of minimally conscious state: its criteria do not inform us about the potential residual consciousness of patients, but they do inform us with certainty about the presence of a cortically mediated state. Based on this constructive criticism review, I suggest three proposals aiming at improving the way we describe the subjective and cognitive state of non-communicating patients. In particular, I present a tentative new classification of impairments of consciousness that combines behavioural evidence with functional brain imaging data, in order to probe directly and univocally residual conscious processes.

Technology-Aided Leisure and Communication Opportunities for Two Post-Coma Persons Emerged from a Minimally Conscious State and Affected by Multiple Disabilities

Science.gov (United States)

Lancioni, Giulio E.; O'Reilly, Mark F.; Singh, Nirbhay N.; Sigafoos, Jeff; Buonocunto, Francesca; Sacco, Valentina; Navarro, Jorge; Lanzilotti, Crocifissa; De Tommaso, Marina; Megna, Marisa; Oliva, Doretta

2013-01-01

This study assessed technology-aided programs for helping two post-coma persons, who had emerged from a minimally conscious state and were affected by multiple disabilities, to (a) engage with leisure stimuli and request caregiver's procedures, (b) send out and listen to text messages for communication with distant partners, and (c) combine…

Design of robust reliable control for T-S fuzzy Markovian jumping delayed neutral type neural networks with probabilistic actuator faults and leakage delays: An event-triggered communication scheme.

Science.gov (United States)

Syed Ali, M; Vadivel, R; Saravanakumar, R

2018-06-01

This study examines the problem of robust reliable control for Takagi-Sugeno (T-S) fuzzy Markovian jumping delayed neural networks with probabilistic actuator faults and leakage terms. An event-triggered communication scheme. First, the randomly occurring actuator faults and their failures rates are governed by two sets of unrelated random variables satisfying certain probabilistic failures of every actuator, new type of distribution based event triggered fault model is proposed, which utilize the effect of transmission delay. Second, Takagi-Sugeno (T-S) fuzzy model is adopted for the neural networks and the randomness of actuators failures is modeled in a Markov jump model framework. Third, to guarantee the considered closed-loop system is exponential mean square stable with a prescribed reliable control performance, a Markov jump event-triggered scheme is designed in this paper, which is the main purpose of our study. Fourth, by constructing appropriate Lyapunov-Krasovskii functional, employing Newton-Leibniz formulation and integral inequalities, several delay-dependent criteria for the solvability of the addressed problem are derived. The obtained stability criteria are stated in terms of linear matrix inequalities (LMIs), which can be checked numerically using the effective LMI toolbox in MATLAB. Finally, numerical examples are given to illustrate the effectiveness and reduced conservatism of the proposed results over the existing ones, among them one example was supported by real-life application of the benchmark problem. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Permissible Delay in Payments

Directory of Open Access Journals (Sweden)

Yung-Fu Huang

2007-01-01

Full Text Available The main purpose of this paper wants to investigate the optimal retailer's lot-sizing policy with two warehouses under partially permissible delay in payments within the economic order quantity (EOQ framework. In this paper, we want to extend that fully permissible delay in payments to the supplier would offer the retailer partially permissible delay in payments. That is, the retailer must make a partial payment to the supplier when the order is received. Then the retailer must pay off the remaining balance at the end of the permissible delay period. In addition, we want to add the assumption that the retailer's storage space is limited. That is, the retailer will rent the warehouse to store these exceeding items when the order quantity is larger than retailer's storage space. Under these conditions, we model the retailer's inventory system as a cost minimization problem to determine the retailer's optimal cycle time and optimal order quantity. Three theorems are developed to efficiently determine the optimal replenishment policy for the retailer. Finally, numerical examples are given to illustrate these theorems and obtained a lot of managerial insights.

Pathophysiological study of chronic subdural hematoma and communicating hydrocephalus with delayed MRI using Gd-DTPA (Magnevist)

Energy Technology Data Exchange (ETDEWEB)

Shinoura, Nobusada; Kondo, Tatsuya; Yamakawa, Kenta; Makiuchi, Tsuneo; Fujii, Kyoichi; Yoshioka, Masumi (National Medical Center of Hospital, Tokyo (Japan))

1991-06-01

Concerning the pathophysiology of chronic subdural hematoma and communicating hydrocephalus, recent studies have been made, but no definitive conclusion has yet been attained. To study their complicated mechanisms, we examined a delayed MRI which was performed 4 hours after the intravenous injection of Gd-diethylenetriaminepentaacetic acid (Gd-DTPA) on 5 cases of subdural hygroma, 3 cases of chronic subdural hematoma after irrigation, one case of hydrocephalus with glioblastoma, and one case of Parkinson syndrome. In every case of subdural hygroma, it was certified that Gd-DTPA was leaked into the cavity of the subdural space. This is perhaps because the outer and inner membranes of the subdural hygroma consist of fibroblasts and of capillary vessels with fenestration; the leakage of blood composition through this fenestration may promote the growth of the membrane and the cavity. The leakage of Gd-DTPA decreased after irrigation, and it did not recur. In the case of hydrocephalus with gioblastoma, there was leakage of Gd-DTPA into the ventricles surrounding the tumor. This may be because of the destruction of the blood-cerebrospinal fluid barrier; perhaps this is associated with the cause of the communicating hydrocephalus. (author).

Pathophysiological study of chronic subdural hematoma and communicating hydrocephalus with delayed MRI using Gd-DTPA (Magnevist)

International Nuclear Information System (INIS)

Shinoura, Nobusada; Kondo, Tatsuya; Yamakawa, Kenta; Makiuchi, Tsuneo; Fujii, Kyoichi; Yoshioka, Masumi

1991-01-01

Concerning the pathophysiology of chronic subdural hematoma and communicating hydrocephalus, recent studies have been made, but no definitive conclusion has yet been attained. To study their complicated mechanisms, we examined a delayed MRI which was performed 4 hours after the intravenous injection of Gd-diethylenetriaminepentaacetic acid (Gd-DTPA) on 5 cases of subdural hygroma, 3 cases of chronic subdural hematoma after irrigation, one case of hydrocephalus with glioblastoma, and one case of Parkinson syndrome. In every case of subdural hygroma, it was certified that Gd-DTPA was leaked into the cavity of the subdural space. This is perhaps because the outer and inner membranes of the subdural hygroma consist of fibroblasts and of capillary vessels with fenestration; the leakage of blood composition through this fenestration may promote the growth of the membrane and the cavity. The leakage of Gd-DTPA decreased after irrigation, and it did not recur. In the case of hydrocephalus with gioblastoma, there was leakage of Gd-DTPA into the ventricles surrounding the tumor. This may be because of the destruction of the blood-cerebrospinal fluid barrier; perhaps this is associated with the cause of the communicating hydrocephalus. (author)

On balancing between minimum energy and minimum delay with radio diversity for wireless sensor networks

DEFF Research Database (Denmark)

Moad, Sofiane; Hansen, Morten Tranberg; Jurdak, RajA

2012-01-01

The expected number of transmissions (ETX) metric represents the link quality in wireless sensor networks, which is highly variable for a specific radio and it can influence dramatically both of the delay and the energy. To adapt to these fluctuations, radio diversity has been recently introduced...... to improve the delivery rate but at the cost of increases in energy for wireless sensor networks. In this paper, we propose a scheme for radio diversity that can balance, depending on the traffic nature in the network, between minimizing the energy consumption or minimizing the end-to-end delay. The proposed...... scheme combines the benefit of two metrics, which aim separately to minimize the energy consumption, and to minimize delay when delivering packets to the end-user. We show by both analysis and simulation that our proposed scheme can adapt to the type of traffic that can occur in a network so...

Variable Delay in port-Hamiltonian Telemanipulation

NARCIS (Netherlands)

Secchi, C; Stramigioli, Stefano; Fantuzzi, C.

2006-01-01

In several applications involving bilateral telemanipulation, master and slave act at different power scales. In this paper a strategy for passively dealing with variable communication delay in scaled port-Hamiltonian based telemanipulation over packet switched networks is proposed.

Delay line MWPC hazard signals inspector

International Nuclear Information System (INIS)

Turner, D.B.; Kirsten, F.; Guiragossian, Z.G.T.; Schilling, R.

1976-01-01

The Hazard Inspector is a CAMAC module which divides a MWPC delay line into 8 independent signal monitor and control segments. Independent control effectively reduces delay line occupation time and cuts the number of background and non-trigger particles accepted by the 4XQT charge-time-pulse-width digitizer, a device presented in a separate communication. Only segments containing legitimate information are digitized. Non-trigger related events are gated out at the digitizer, and contaminating hits are noted for computer correction

Multi-Gbit/s optical phase chaos communications using a time-delayed optoelectronic oscillator with a three-wave interferometer nonlinearity.

Science.gov (United States)

Oden, Jérémy; Lavrov, Roman; Chembo, Yanne K; Larger, Laurent

2017-11-01

We propose a chaos communication scheme based on a chaotic optical phase carrier generated with an optoelectronic oscillator with nonlinear time-delay feedback. The system includes a dedicated non-local nonlinearity, which is a customized three-wave imbalanced interferometer. This particular feature increases the complexity of the chaotic waveform and thus the security of the transmitted information, as these interferometers are characterized by four independent parameters which are part of the secret key for the chaos encryption scheme. We first analyze the route to chaos in the system, and evidence a sequence of period doubling bifurcations from the steady-state to fully developed chaos. Then, in the chaotic regime, we study the synchronization between the emitter and the receiver, and achieve chaotic carrier cancellation with a signal-to-noise ratio up to 20 dB. We finally demonstrate error-free chaos communications at a data rate of 3 Gbit/s.

Multi-Gbit/s optical phase chaos communications using a time-delayed optoelectronic oscillator with a three-wave interferometer nonlinearity

Science.gov (United States)

Oden, Jérémy; Lavrov, Roman; Chembo, Yanne K.; Larger, Laurent

2017-11-01

We propose a chaos communication scheme based on a chaotic optical phase carrier generated with an optoelectronic oscillator with nonlinear time-delay feedback. The system includes a dedicated non-local nonlinearity, which is a customized three-wave imbalanced interferometer. This particular feature increases the complexity of the chaotic waveform and thus the security of the transmitted information, as these interferometers are characterized by four independent parameters which are part of the secret key for the chaos encryption scheme. We first analyze the route to chaos in the system, and evidence a sequence of period doubling bifurcations from the steady-state to fully developed chaos. Then, in the chaotic regime, we study the synchronization between the emitter and the receiver, and achieve chaotic carrier cancellation with a signal-to-noise ratio up to 20 dB. We finally demonstrate error-free chaos communications at a data rate of 3 Gbit/s.

Quadratic theory and feedback controllers for linear time delay systems

International Nuclear Information System (INIS)

Lee, E.B.

1976-01-01

Recent research on the design of controllers for systems having time delays is discussed. Results for the ''open loop'' and ''closed loop'' designs will be presented. In both cases results for minimizing a quadratic cost functional are given. The usefulness of these results is not known, but similar results for the non-delay case are being routinely applied. (author)

Delayed splenic rupture presenting 70 days following blunt abdominal trauma.

Science.gov (United States)

Resteghini, Nancy; Nielsen, Jonpaul; Hoimes, Matthew L; Karam, Adib R

2014-01-01

Delayed splenic rupture following conservative management of splenic injury is an extremely rare complication. We report a case of an adult patient who presented with delayed splenic rupture necessitating splenectomy, 2 months following blunt abdominal trauma. Imaging at the initial presentation demonstrated only minimal splenic contusion and the patient was discharge following 24 hours of observation. © 2014.

Separations: The path to waste minimization

International Nuclear Information System (INIS)

Bell, J.T.

1992-01-01

Waste materials usually are composed of large amounts of innocuous and frequently useful components mixed with lesser amounts of one or more hazardous components. The ultimate path to waste minimization is the separation of the lesser quantities of hazardous components from the innocuous components, and then recycle the useful components. This vision is so simple that everyone would be expected to properly manage waste. Several parameters interfere with this proper waste management, which encourages the open-quotes sweep it under the rugclose quotes or the open-quotes bury it allclose quotes attitudes, both of which delay and complicate proper waste management. The two primary parameters that interfere with proper waste management are: economics drives a process to a product without concerns of waste minimization, and emergency needs for immediate production of a product usually delays proper waste management. A third parameter in recent years is also interfering with proper waste management: quick relief of waste insults to political and public perceptions is promoting the open-quotes bury it allclose quotes attitude. A fourth parameter can promote better waste management for any scenario that suffers either or all of the first three parameters: separations technology can minimize wastes when the application of this technology is not voided by influence of the first three parameters. The US Department of Energy's management of nuclear waste has been seriously affected by the above four parameters. This paper includes several points about how the generation and management of DOE wastes have been, and continue to be, affected by these parameters. Particular separations technologies for minimizing the DOE wastes that must be stored for long periods are highlighted

Aperiodic linear networked control considering variable channel delays: application to robots coordination.

Science.gov (United States)

Santos, Carlos; Espinosa, Felipe; Santiso, Enrique; Mazo, Manuel

2015-05-27

One of the main challenges in wireless cyber-physical systems is to reduce the load of the communication channel while preserving the control performance. In this way, communication resources are liberated for other applications sharing the channel bandwidth. The main contribution of this work is the design of a remote control solution based on an aperiodic and adaptive triggering mechanism considering the current network delay of multiple robotics units. Working with the actual network delay instead of the maximum one leads to abandoning this conservative assumption, since the triggering condition is fixed depending on the current state of the network. This way, the controller manages the usage of the wireless channel in order to reduce the channel delay and to improve the availability of the communication resources. The communication standard under study is the widespread IEEE 802.11g, whose channel delay is clearly uncertain. First, the adaptive self-triggered control is validated through the TrueTime simulation tool configured for the mentioned WiFi standard. Implementation results applying the aperiodic linear control laws on four P3-DX robots are also included. Both of them demonstrate the advantage of this solution in terms of network accessing and control performance with respect to periodic and non-adaptive self-triggered alternatives.

Aperiodic Linear Networked Control Considering Variable Channel Delays: Application to Robots Coordination

Directory of Open Access Journals (Sweden)

Carlos Santos

2015-05-01

Full Text Available One of the main challenges in wireless cyber-physical systems is to reduce the load of the communication channel while preserving the control performance. In this way, communication resources are liberated for other applications sharing the channel bandwidth. The main contribution of this work is the design of a remote control solution based on an aperiodic and adaptive triggering mechanism considering the current network delay of multiple robotics units. Working with the actual network delay instead of the maximum one leads to abandoning this conservative assumption, since the triggering condition is fixed depending on the current state of the network. This way, the controller manages the usage of the wireless channel in order to reduce the channel delay and to improve the availability of the communication resources. The communication standard under study is the widespread IEEE 802.11g, whose channel delay is clearly uncertain. First, the adaptive self-triggered control is validated through the TrueTime simulation tool configured for the mentioned WiFi standard. Implementation results applying the aperiodic linear control laws on four P3-DX robots are also included. Both of them demonstrate the advantage of this solution in terms of network accessing and control performance with respect to periodic and non-adaptive self-triggered alternatives.

Standardised risk analysis as a communication tool

International Nuclear Information System (INIS)

Pluess, Ch.; Montanarini, M.; Bernauer, M.

1998-01-01

Full text of publication follows: several European countries require a risk analysis for the production, storage or transport a dangerous goods. This requirement imposes considerable administrative effort for some sectors of the industry. In order to minimize the effort of such studies, a generic risk analysis for an industrial sector proved to help. Standardised procedures can consequently be derived for efficient performance of the risk investigations. This procedure was successfully established in Switzerland for natural gas transmission lines and fossil fuel storage plants. The development process of the generic risk analysis involved an intense discussion between industry and authorities about methodology of assessment and the criteria of acceptance. This process finally led to scientific consistent modelling tools for risk analysis and to an improved communication from the industry to the authorities and the public. As a recent example, the Holland-Italy natural gas transmission pipeline is demonstrated, where this method was successfully employed. Although this pipeline traverses densely populated areas in Switzerland, using this established communication method, the risk problems could be solved without delaying the planning process. (authors)

Defining Tolerance: Impacts of Delay and Disruption when Managing Challenged Networks

Science.gov (United States)

Birrane, Edward J. III; Burleigh, Scott C.; Cerf, Vint

2011-01-01

Challenged networks exhibit irregularities in their communication performance stemming from node mobility, power constraints, and impacts from the operating environment. These irregularities manifest as high signal propagation delay and frequent link disruption. Understanding those limits of link disruption and propagation delay beyond which core networking features fail is an ongoing area of research. Various wireless networking communities propose tools and techniques that address these phenomena. Emerging standardization activities within the Internet Research Task Force (IRTF) and the Consultative Committee for Space Data Systems (CCSDS) look to build upon both this experience and scalability analysis. Successful research in this area is predicated upon identifying enablers for common communication functions (notably node discovery, duplex communication, state caching, and link negotiation) and how increased disruptions and delays affect their feasibility within the network. Networks that make fewer assumptions relating to these enablers provide more universal service. Specifically, reliance on node discovery and link negotiation results in network-specific operational concepts rather than scalable technical solutions. Fundamental to this debate are the definitions, assumptions, operational concepts, and anticipated scaling of these networks. This paper presents the commonalities and differences between delay and disruption tolerance, including support protocols and critical enablers. We present where and how these tolerances differ. We propose a set of use cases that must be accommodated by any standardized delay-tolerant network and discuss the implication of these on existing tool development.

Two-Channel Transparency-Optimized Control Architectures in Bilateral Teleoperation With Time Delay.

Science.gov (United States)

Kim, Jonghyun; Chang, Pyung Hun; Park, Hyung-Soon

2013-01-01

This paper introduces transparency-optimized control architectures (TOCAs) using two communication channels. Two classes of two-channel TOCAs are found, thereby showing that two channels are sufficient to achieve transparency. These TOCAs achieve a greater level of transparency but poorer stability than three-channel TOCAs and four-channel TOCAs. Stability of the two-channel TOCAs has been enhanced while minimizing transparency degradation by adding a filter; and a combined use of the two classes of two-channel TOCAs is proposed for both free space and constrained motion, which involve switching between two TOCAs for transition between free space and constrained motions. The stability condition of the switched teleoperation system is derived for practical applications. Through the one degree-of-freedom (DOF) experiment, the proposed two-channel TOCAs were shown to operate stably, while achieving better transparency under time delay than the other TOCAs.

Minimal requirements of ACR-NEMA digital imaging and communication standards

International Nuclear Information System (INIS)

Wang, Y.; Horrii, S.; Lehr, J.

1986-01-01

The American College of Radiology-National Electrical Manufacturers Association (ACR-NEMA) Digital Imaging and Communication Standards were formally adopted in December 1985. They are intended to facilitate management and communication of digital image information regardless of source, format, or device manufacturer; to promote the development and expansion of radiologic imaging and communication systems that can also interface with other systems of hospital information; and to allow the creation of diagnostic information databases that can be interrogated by a wide variety of devices distributed geographically. The Standards specify the hardware interface, a minimum set of software commands, and a consistent set of data formats for communication across the interface between an imaging device and a network interface unit or another imaging device

Impact of sensing errors on the queueing delay and transmit power in cognitive radio access

KAUST Repository

Hamza, Doha R.; Aissa, Sonia

2011-01-01

We study a multiple-access system with a primary user (PU) and a secondary user (SU) utilizing the same frequency band and communicating with a common receiver. Both users transmit with a fixed transmission rate by employing a channel inversion power control scheme. The SU transmits with a certain probability that depends on the sensing outcome, its queue length and whether it has a new packet arrival. We consider the case of erroneous sensing. The goal of the SU is to find the optimal transmission scheduling policy so as to minimize its queueing delay under constraints on its average transmit power and the maximum tolerable primary outage probability caused by miss-detection. The access probabilities are obtained efficiently using linear programming. © 2011 IEEE.

Impact of sensing errors on the queueing delay and transmit power in cognitive radio access

KAUST Repository

Hamza, Doha R.

2011-03-01

We study a multiple-access system with a primary user (PU) and a secondary user (SU) utilizing the same frequency band and communicating with a common receiver. Both users transmit with a fixed transmission rate by employing a channel inversion power control scheme. The SU transmits with a certain probability that depends on the sensing outcome, its queue length and whether it has a new packet arrival. We consider the case of erroneous sensing. The goal of the SU is to find the optimal transmission scheduling policy so as to minimize its queueing delay under constraints on its average transmit power and the maximum tolerable primary outage probability caused by miss-detection. The access probabilities are obtained efficiently using linear programming. © 2011 IEEE.

Bidirectional communication using delay coupled chaotic directly ...

Indian Academy of Sciences (India)

Corresponding author. ... 30 September 2009. Abstract. Chaotic synchronization of two directly modulated semiconductor lasers with ... For InGaAsP lasers used in optical communication systems, the nonlinear gain re- duction is very strong and its ...

Stability analysis and synchronization in discrete-time complex networks with delayed coupling

Science.gov (United States)

Cheng, Ranran; Peng, Mingshu; Yu, Weibin; Sun, Bo; Yu, Jinchen

2013-12-01

A new network of coupled maps is proposed in which the connections between units involve no delays but the intra-neural communication does, whereas in the work of Atay et al. [Phys. Rev. Lett. 92, 144101 (2004)], the focus is on information processing delayed by the inter-neural communication. We show that the synchronization of the network depends on not only the intrinsic dynamical features and inter-connection topology (characterized by the spectrum of the graph Laplacian) but also the delays and the coupling strength. There are two main findings: (i) the more neighbours, the easier to be synchronized; (ii) odd delays are easier to be synchronized than even ones. In addition, compared with those discussed by Atay et al. [Phys. Rev. Lett. 92, 144101 (2004)], our model has a better synchronizability for regular networks and small-world variants.

A lossy graph model for delay reduction in generalized instantly decodable network coding

KAUST Repository

Douik, Ahmed S.

2014-06-01

The problem of minimizing the decoding delay in Generalized instantly decodable network coding (G-IDNC) for both perfect and lossy feedback scenarios is formulated as a maximum weight clique problem over the G-IDNC graph in. In this letter, we introduce a new lossy G-IDNC graph (LG-IDNC) model to further minimize the decoding delay in lossy feedback scenarios. Whereas the G-IDNC graph represents only doubtless combinable packets, the LG-IDNC graph represents also uncertain packet combinations, arising from lossy feedback events, when the expected decoding delay of XORing them among themselves or with other certain packets is lower than that expected when sending these packets separately. We compare the decoding delay performance of LG-IDNC and G-IDNC graphs through extensive simulations. Numerical results show that our new LG-IDNC graph formulation outperforms the G-IDNC graph formulation in all lossy feedback situations and achieves significant improvement in the decoding delay especially when the feedback erasure probability is higher than the packet erasure probability. © 2012 IEEE.

Robust stability bounds for multi-delay networked control systems

Science.gov (United States)

Seitz, Timothy; Yedavalli, Rama K.; Behbahani, Alireza

2018-04-01

In this paper, the robust stability of a perturbed linear continuous-time system is examined when controlled using a sampled-data networked control system (NCS) framework. Three new robust stability bounds on the time-invariant perturbations to the original continuous-time plant matrix are presented guaranteeing stability for the corresponding discrete closed-loop augmented delay-free system (ADFS) with multiple time-varying sensor and actuator delays. The bounds are differentiated from previous work by accounting for the sampled-data nature of the NCS and for separate communication delays for each sensor and actuator, not a single delay. Therefore, this paper expands the knowledge base in multiple inputs multiple outputs (MIMO) sampled-data time delay systems. Bounds are presented for unstructured, semi-structured, and structured perturbations.

Delay and Disruption Tolerant Networking MACHETE Model

Science.gov (United States)

Segui, John S.; Jennings, Esther H.; Gao, Jay L.

2011-01-01

To verify satisfaction of communication requirements imposed by unique missions, as early as 2000, the Communications Networking Group at the Jet Propulsion Laboratory (JPL) saw the need for an environment to support interplanetary communication protocol design, validation, and characterization. JPL's Multi-mission Advanced Communications Hybrid Environment for Test and Evaluation (MACHETE), described in Simulator of Space Communication Networks (NPO-41373) NASA Tech Briefs, Vol. 29, No. 8 (August 2005), p. 44, combines various commercial, non-commercial, and in-house custom tools for simulation and performance analysis of space networks. The MACHETE environment supports orbital analysis, link budget analysis, communications network simulations, and hardware-in-the-loop testing. As NASA is expanding its Space Communications and Navigation (SCaN) capabilities to support planned and future missions, building infrastructure to maintain services and developing enabling technologies, an important and broader role is seen for MACHETE in design-phase evaluation of future SCaN architectures. To support evaluation of the developing Delay Tolerant Networking (DTN) field and its applicability for space networks, JPL developed MACHETE models for DTN Bundle Protocol (BP) and Licklider/Long-haul Transmission Protocol (LTP). DTN is an Internet Research Task Force (IRTF) architecture providing communication in and/or through highly stressed networking environments such as space exploration and battlefield networks. Stressed networking environments include those with intermittent (predictable and unknown) connectivity, large and/or variable delays, and high bit error rates. To provide its services over existing domain specific protocols, the DTN protocols reside at the application layer of the TCP/IP stack, forming a store-and-forward overlay network. The key capabilities of the Bundle Protocol include custody-based reliability, the ability to cope with intermittent connectivity

Delay propagation and process management at railway stations

NARCIS (Netherlands)

Goverde, R.M.P.; Hansen, I.A.

2001-01-01

Process operators at large railway stations have the difficult task to secure a fluent train traffic flow while minimizing deviations from established timetables. Variation in actual train departure times is inevitable due to many circumstances such as arrival delays and fluctuations in alighting

Dynamical regimes and intracavity propagation delay in external ...

Indian Academy of Sciences (India)

E JAYAPRASATH

MS received 14 November 2016; revised 3 May 2017; accepted 1 June 2017; published online 31 October 2017. Abstract. Intracavity ... In order to implement secure optical communication, .... Dependence of intracavity propagation delay on.

Congestion control for vehicular delay tolerant network routing protocols

OpenAIRE

Oham, Chuka Finbars

2014-01-01

The Vehicular Delay Tolerant Network (VDTN) is a special and challenging type of the Delay Tolerant Network because of its high mobility, frequent disconnections and nodal congestion features. These challenging features make it prone to congestion which leads to a considerable amount of message drops in the network. To minimize the impact of congestion in the network, we designed and implemented the Congestion Aware Spray and Wait (CASaW) routing protocol. We varied the buffer sizes of the no...

Iterative Decoding for an Optical CDMA based Laser communication System

International Nuclear Information System (INIS)

Kim, Jin Young; Kim, Eun Cheol; Cha, Jae Sang

2008-01-01

An optical CDMA(code division multiple access)based Laser communication system has attracted much attention since it requires minimal optical Laser signal processing and it is virtually delay free, while from the theoretical point of view, its performance depends on the auto and cross correlation properties of employed sequences. Various kinds of channel coding schemes for optical CDMA based Laser communication systems have been proposed and analyzed to compensate nonideal channel and receiver conditions in impaired photon channels. In this paper, we propose and analyze an iterative decoding of optical CDMA based Laser communication signals for both shot noise limited and thermal noise limited systems. It is assumed that optical channel is an intensity modulated (IM)channel and direct detection scheme is employed to detect the received optical signal. The performance is evaluated in terms of bit error probability and throughput. It is demonstrated that the BER and throughput performance is substantially improved with interleaver length for a fixed code rate and with alphabet size of PPM (pulse position modulation). Also, the BER and throughput performance is significantly enhanced with the number of iterations for decoding process. The results in this paper can be applied to the optical CDMA based Laser communication network with multiple access applications

Iterative Decoding for an Optical CDMA based Laser communication System

Energy Technology Data Exchange (ETDEWEB)

Kim, Jin Young; Kim, Eun Cheol [Kwangwoon Univ., Seoul (Korea, Republic of); Cha, Jae Sang [Seoul National Univ. of Technology, Seoul (Korea, Republic of)

2008-11-15

An optical CDMA(code division multiple access)based Laser communication system has attracted much attention since it requires minimal optical Laser signal processing and it is virtually delay free, while from the theoretical point of view, its performance depends on the auto and cross correlation properties of employed sequences. Various kinds of channel coding schemes for optical CDMA based Laser communication systems have been proposed and analyzed to compensate nonideal channel and receiver conditions in impaired photon channels. In this paper, we propose and analyze an iterative decoding of optical CDMA based Laser communication signals for both shot noise limited and thermal noise limited systems. It is assumed that optical channel is an intensity modulated (IM)channel and direct detection scheme is employed to detect the received optical signal. The performance is evaluated in terms of bit error probability and throughput. It is demonstrated that the BER and throughput performance is substantially improved with interleaver length for a fixed code rate and with alphabet size of PPM (pulse position modulation). Also, the BER and throughput performance is significantly enhanced with the number of iterations for decoding process. The results in this paper can be applied to the optical CDMA based Laser communication network with multiple access applications.

Numerical modelling of multimode fibre-optic communication lines

Energy Technology Data Exchange (ETDEWEB)

Sidelnikov, O S; Fedoruk, M P [Novosibirsk State University, Novosibirsk (Russian Federation); Sygletos, S; Ferreira, F [Aston University, England, Birmingham, B4 7ET (United Kingdom)

2016-01-31

The results of numerical modelling of nonlinear propagation of an optical signal in multimode fibres with a small differential group delay are presented. It is found that the dependence of the error vector magnitude (EVM) on the differential group delay can be reduced by increasing the number of ADC samples per symbol in the numerical implementation of the differential group delay compensation algorithm in the receiver. The possibility of using multimode fibres with a small differential group delay for data transmission in modern digital communication systems is demonstrated. It is shown that with increasing number of modes the strong coupling regime provides a lower EVM level than the weak coupling one. (fibre-optic communication lines)

Signal Propagation Delay as a Barrier to Control Applications in WAN

DEFF Research Database (Denmark)

Knudsen, Thomas Phillip; Patel, A.; Pedersen, Jens Myrup

With the advent in WAN of delay sensitive technical applications, such as remote control, signal propagation delay becomes a major problem. The extent of the problem is analysed by lower bounding the delay in relation to different transmission media. Requirements for reliability and bandwidth are...... are considered. The consequences of this bounding for communication network planning and provisioning are discussed in relation to mitigating the effects of signal propagation delay as a barrier to the penetration of control applications into WAN......With the advent in WAN of delay sensitive technical applications, such as remote control, signal propagation delay becomes a major problem. The extent of the problem is analysed by lower bounding the delay in relation to different transmission media. Requirements for reliability and bandwidth...

A Game-theoretic Framework for Network Coding Based Device-to-Device Communications

KAUST Repository

Douik, Ahmed S.; Sorour, Sameh; Tembine, Hamidou; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

2016-01-01

This paper investigates the delay minimization problem for instantly decodable network coding (IDNC) based deviceto- device (D2D) communications. In D2D enabled systems, users cooperate to recover all their missing packets. The paper proposes a game theoretic framework as a tool for improving the distributed solution by overcoming the need for a central controller or additional signaling in the system. The session is modeled by self-interested players in a non-cooperative potential game. The utility functions are designed so as increasing individual payoff results in a collective behavior achieving both a desirable system performance in a shared network environment and the Nash equilibrium. Three games are developed whose first reduces the completion time, the second the maximum decoding delay and the third the sum decoding delay. The paper, further, improves the formulations by including a punishment policy upon collision occurrence so as to achieve the Nash bargaining solution. Learning algorithms are proposed for systems with complete and incomplete information, and for the imperfect feedback scenario. Numerical results suggest that the proposed game-theoretical formulation provides appreciable performance gain against the conventional point-to-multipoint (PMP), especially for reliable user-to-user channels.

A Game-theoretic Framework for Network Coding Based Device-to-Device Communications

KAUST Repository

Douik, Ahmed

2016-06-29

This paper investigates the delay minimization problem for instantly decodable network coding (IDNC) based deviceto- device (D2D) communications. In D2D enabled systems, users cooperate to recover all their missing packets. The paper proposes a game theoretic framework as a tool for improving the distributed solution by overcoming the need for a central controller or additional signaling in the system. The session is modeled by self-interested players in a non-cooperative potential game. The utility functions are designed so as increasing individual payoff results in a collective behavior achieving both a desirable system performance in a shared network environment and the Nash equilibrium. Three games are developed whose first reduces the completion time, the second the maximum decoding delay and the third the sum decoding delay. The paper, further, improves the formulations by including a punishment policy upon collision occurrence so as to achieve the Nash bargaining solution. Learning algorithms are proposed for systems with complete and incomplete information, and for the imperfect feedback scenario. Numerical results suggest that the proposed game-theoretical formulation provides appreciable performance gain against the conventional point-to-multipoint (PMP), especially for reliable user-to-user channels.

Two-Channel Transparency-Optimized Control Architectures in Bilateral Teleoperation With Time Delay

Science.gov (United States)

Kim, Jonghyun; Chang, Pyung Hun; Park, Hyung-Soon

2013-01-01

This paper introduces transparency-optimized control architectures (TOCAs) using two communication channels. Two classes of two-channel TOCAs are found, thereby showing that two channels are sufficient to achieve transparency. These TOCAs achieve a greater level of transparency but poorer stability than three-channel TOCAs and four-channel TOCAs. Stability of the two-channel TOCAs has been enhanced while minimizing transparency degradation by adding a filter; and a combined use of the two classes of two-channel TOCAs is proposed for both free space and constrained motion, which involve switching between two TOCAs for transition between free space and constrained motions. The stability condition of the switched teleoperation system is derived for practical applications. Through the one degree-of-freedom (DOF) experiment, the proposed two-channel TOCAs were shown to operate stably, while achieving better transparency under time delay than the other TOCAs. PMID:23833548

On the performance of data receivers with a restricted detection delay

NARCIS (Netherlands)

Bergmans, J.W.M.; Willems, F.M.J.; Kerpen, G.S.M.

1994-01-01

It is well known that the performance of a data receiver for an intersymbol interference (ISI) channel can depend strongly on the detection delay d. For a discrete-time communication system, this paper derives a lower bound on the bit-error probability as a function of d. This "restricted delay

Interplay of delay and multiplexing: Impact on cluster synchronization

Science.gov (United States)

Singh, Aradhana; Jalan, Sarika; Boccaletti, Stefano

2017-04-01

Communication delays and multiplexing are ubiquitous features of real-world network systems. We here introduce a simple model where these two features are simultaneously present and report the rich phenomenology which is actually due to their interplay on cluster synchronization. A delay in one layer has non trivial impacts on the collective dynamics of the other layers, enhancing or suppressing synchronization. At the same time, multiplexing may also enhance cluster synchronization of delayed layers. We elucidate several nontrivial (and anti-intuitive) scenarios, which are of interest and potential application in various real-world systems, where the introduction of a delay may render synchronization of a layer robust against changes in the properties of the other layers.

The Picture Exchange Communication System (PECS): A Promising Method for Improving Communication Skills of Learners with Autism Spectrum Disorders

Science.gov (United States)

Ganz, Jennifer B.; Simpson, Richard L.; Lund, Emily M.

2012-01-01

Children and youth with autism spectrum disorders (ASD) and other developmental delays frequently experience deficits in functional communication. Identifying and using suitable communication enhancement and augmentative and alternative communication supports is essential to achievement of positive outcomes for these learners. This article…

Real-time traffic signal optimization model based on average delay time per person

Directory of Open Access Journals (Sweden)

Pengpeng Jiao

2015-10-01

Full Text Available Real-time traffic signal control is very important for relieving urban traffic congestion. Many existing traffic control models were formulated using optimization approach, with the objective functions of minimizing vehicle delay time. To improve people’s trip efficiency, this article aims to minimize delay time per person. Based on the time-varying traffic flow data at intersections, the article first fits curves of accumulative arrival and departure vehicles, as well as the corresponding functions. Moreover, this article transfers vehicle delay time to personal delay time using average passenger load of cars and buses, employs such time as the objective function, and proposes a signal timing optimization model for intersections to achieve real-time signal parameters, including cycle length and green time. This research further implements a case study based on practical data collected at an intersection in Beijing, China. The average delay time per person and queue length are employed as evaluation indices to show the performances of the model. The results show that the proposed methodology is capable of improving traffic efficiency and is very effective for real-world applications.

Delay-Limited Capacity in the Low Power Regime

KAUST Repository

Rezki, Zouheir

2016-02-11

Outage performance of the M-block fading with additive white Gaussian noise (BF-AWGN) is investigated in the low-power regime. We consider delay-constrained constant-rate communications with perfect channel state information (CSI) at both the transmitter and the receiver (CSI-TR), under a shortterm power constraint (STPC) and a long-term power constraint (LTPC). Subject to STPC, we show that selection diversity that allocates all the power to the strongest block is asymptotically optimal. Then, we provide a simple characterization of the outage probability in the regime of interest. We quantify the reward due to CSI-TR over the constant-rate constant-power scheme and show that this reward increases with the delay constraint. For instance, for Rayleigh fading, we find that a power gain up to 4.3 dB is achievable. Subject to LTPC, we show that the above guidelines still holds and that the outage performance improves due to the flexibility of the LTPC over the STPC. More interestingly, we prove that LTPC allows zero-outage communication even at low SNR and characterize the delaylimited capacity at low SNR in a simple form. More precisely, we establish that the delay-limited capacity scales linearly with the power constraint, for a given M < 1. Our framework highlights the benefit of fading at low SNR as the delay-limited capacity may outperform the AWGN capacity. For instance, for Rayleigh fading and with M = 3, the delay-limited capacity is 16% higher than the capacity of an AWGN channel.

Projective synchronization of time-varying delayed neural network with adaptive scaling factors

International Nuclear Information System (INIS)

Ghosh, Dibakar; Banerjee, Santo

2013-01-01

Highlights: • Projective synchronization in coupled delayed neural chaotic systems with modulated delay time is introduced. • An adaptive rule for the scaling factors is introduced. • This scheme is highly applicable in secure communication. -- Abstract: In this work, the projective synchronization between two continuous time delayed neural systems with time varying delay is investigated. A sufficient condition for synchronization for the coupled systems with modulated delay is presented analytically with the help of the Krasovskii–Lyapunov approach. The effect of adaptive scaling factors on synchronization are also studied in details. Numerical simulations verify the effectiveness of the analytic results

Generalized synchronization-based multiparameter estimation in modulated time-delayed systems

Science.gov (United States)

Ghosh, Dibakar; Bhattacharyya, Bidyut K.

2011-09-01

We propose a nonlinear active observer based generalized synchronization scheme for multiparameter estimation in time-delayed systems with periodic time delay. A sufficient condition for parameter estimation is derived using Krasovskii-Lyapunov theory. The suggested tool proves to be globally and asymptotically stable by means of Krasovskii-Lyapunov method. With this effective method, parameter identification and generalized synchronization of modulated time-delayed systems with all the system parameters unknown, can be achieved simultaneously. We restrict our study for multiple parameter estimation in modulated time-delayed systems with single state variable only. Theoretical proof and numerical simulation demonstrate the effectiveness and feasibility of the proposed technique. The block diagram of electronic circuit for multiple time delay system shows that the method is easily applicable in practical communication problems.

Waste minimization at Chalk River Laboratories

Energy Technology Data Exchange (ETDEWEB)

Kranz, P.; Wong, P.C.F. [Atomic Energy of Canada Limited, Chalk River, ON (Canada)

2011-07-01

Waste minimization supports Atomic Energy of Canada Limited (AECL) Environment Policy with regard to pollution prevention and has positive impacts on the environment, human health and safety, and economy. In accordance with the principle of pollution prevention, the quantities and degree of hazard of wastes requiring storage or disposition at facilities within or external to AECL sites shall be minimized, following the principles of Prevent, Reduce, Reuse, and Recycle, to the extent practical. Waste minimization is an important element in the Waste Management Program. The Waste Management Program has implemented various initiatives for waste minimization since 2007. The key initiatives have focused on waste reduction, segregation and recycling, and included: 1) developed waste minimization requirements and recycling procedure to establish the framework for applying the Waste Minimization Hierarchy; 2) performed waste minimization assessments for the facilities, which generate significant amounts of waste, to identify the opportunities for waste reduction and assist the waste generators to develop waste reduction targets and action plans to achieve the targets; 3) implemented the colour-coded, standardized waste and recycling containers to enhance waste segregation; 4) established partnership with external agents for recycling; 5) extended the likely clean waste and recyclables collection to selected active areas; 6) provided on-going communications to promote waste reduction and increase awareness for recycling; and 7) continually monitored performance, with respect to waste minimization, to identify opportunities for improvement and to communicate these improvements. After implementation of waste minimization initiatives at CRL, the solid waste volume generated from routine operations at CRL has significantly decreased, while the amount of recyclables diverted from the onsite landfill has significantly increased since 2007. The overall refuse volume generated at

Waste minimization at Chalk River Laboratories

International Nuclear Information System (INIS)

Kranz, P.; Wong, P.C.F.

2011-01-01

Waste minimization supports Atomic Energy of Canada Limited (AECL) Environment Policy with regard to pollution prevention and has positive impacts on the environment, human health and safety, and economy. In accordance with the principle of pollution prevention, the quantities and degree of hazard of wastes requiring storage or disposition at facilities within or external to AECL sites shall be minimized, following the principles of Prevent, Reduce, Reuse, and Recycle, to the extent practical. Waste minimization is an important element in the Waste Management Program. The Waste Management Program has implemented various initiatives for waste minimization since 2007. The key initiatives have focused on waste reduction, segregation and recycling, and included: 1) developed waste minimization requirements and recycling procedure to establish the framework for applying the Waste Minimization Hierarchy; 2) performed waste minimization assessments for the facilities, which generate significant amounts of waste, to identify the opportunities for waste reduction and assist the waste generators to develop waste reduction targets and action plans to achieve the targets; 3) implemented the colour-coded, standardized waste and recycling containers to enhance waste segregation; 4) established partnership with external agents for recycling; 5) extended the likely clean waste and recyclables collection to selected active areas; 6) provided on-going communications to promote waste reduction and increase awareness for recycling; and 7) continually monitored performance, with respect to waste minimization, to identify opportunities for improvement and to communicate these improvements. After implementation of waste minimization initiatives at CRL, the solid waste volume generated from routine operations at CRL has significantly decreased, while the amount of recyclables diverted from the onsite landfill has significantly increased since 2007. The overall refuse volume generated at

Delays in the management of retroperitoneal sarcomas

DEFF Research Database (Denmark)

Seinen, Jojanneke; Almquist, Martin; Styring, Emelie

2010-01-01

Retroperitoneal sarcomas are rare and treatment should optimally be centralized. Despite successful centralization with 90% of the patients referred prior to surgery, delays occur, which led us to assess lead times in a population-based series. Method. Patients diagnosed with retroperitoneal...... sarcoma in the southern Sweden health care region 2003-2009 were eligible for the study. Data on referrals and diagnostic investigations were collected from clinical files from primary health care, local hospitals, and from the sarcoma centre. Lead times were divided into patient delays and health care...... at the general practitioner, 36 days at local hospitals, and 55 days at the sarcoma centre. Conclusion. Centralization per se is not sufficient for optimized and efficient management. Our findings suggest that delays can be minimized by direct referral of patients from primary health care to sarcoma centers...

Understanding Housing Delays and Relocations Within the Housing First Model.

Science.gov (United States)

Zerger, Suzanne; Pridham, Katherine Francombe; Jeyaratnam, Jeyagobi; Hwang, Stephen W; O'Campo, Patricia; Kohli, Jaipreet; Stergiopoulos, Vicky

2016-01-01

This study explores factors contributing to delays and relocations during the implementation of the Housing First model in Toronto, Ontario. While interruptions in housing tenure are expected en route to recovery and housing stability, consumer and service provider views on finding and keeping housing remain largely unknown. In-person interviews and focus groups were conducted with 48 study participants, including 23 case managers or housing workers and 25 consumers. The following three factors contributed to housing delays and transfers: (1) the effectiveness of communication and collaboration among consumers and service providers, (2) consumer-driven preferences and ambivalence, and (3) provider prioritization of consumer choice over immediate housing access. Two strategies--targeted communications and consumer engagement in housing searches--supported the housing process. Several factors affect the timing and stability of housing. Communication between and among providers and consumers, and a shared understanding of consumer choice, can further support choice and recovery.

Nonlinear smith-predictor based control strategy for a unicycle mobile robot subject to transport delay

NARCIS (Netherlands)

Alvarez Aguirre, A.; Velasco-Villa, M.; Del Muro Cuellar, B.

2008-01-01

This paper consider the remote control of an unicycle mobile robot subject to transport delay. The communication delay effects are considered by means of a discrete time approach that allows to solve the path tracking problem in terms of the delayed input. The causality problem involved in the

Minimally-Invasive Neural Interface for Distributed Wireless Electrocorticogram Recording Systems.

Science.gov (United States)

Chang, Sun-Il; Park, Sung-Yun; Yoon, Euisik

2018-01-17

This paper presents a minimally-invasive neural interface for distributed wireless electrocorticogram (ECoG) recording systems. The proposed interface equips all necessary components for ECoG recording, such as the high performance front-end integrated circuits, a fabricated flexible microelectrode array, and wireless communication inside a miniaturized custom-made platform. The multiple units of the interface systems can be deployed to cover a broad range of the target brain region and transmit signals via a built-in intra-skin communication (ISCOM) module. The core integrated circuit (IC) consists of 16-channel, low-power push-pull double-gated preamplifiers, in-channel successive approximation register analog-to-digital converters (SAR ADC) with a single-clocked bootstrapping switch and a time-delayed control unit, an ISCOM module for wireless data transfer through the skin instead of a power-hungry RF wireless transmitter, and a monolithic voltage/current reference generator to support the aforementioned analog and mixed-signal circuit blocks. The IC was fabricated using 250 nm CMOS processes in an area of 3.2 × 0.9 mm² and achieved the low-power operation of 2.5 µW per channel. Input-referred noise was measured as 5.62 µV rms for 10 Hz to 10 kHz and ENOB of 7.21 at 31.25 kS/s. The implemented system successfully recorded multi-channel neural activities in vivo from a primate and demonstrated modular expandability using the ISCOM with power consumption of 160 µW.

On the Delay-Energy Tradeoff in Multiuser Fading Channels

Directory of Open Access Journals (Sweden)

Ralf R. Müller

2009-01-01

Full Text Available We consider the delay-energy tradeoff on a fading channel with multiuser diversity. For fixed arbitrary rates of the users, the total transmitted energy is minimized subject to a delay constraint. To achieve this goal we propose a scheme which schedules a subset of all users simultaneously. The scheduled users are allocated power to guarantee successful separation at the detector by successive decoding. In this way, we can benefit from both multiuser diversity and the near-far situation via scheduling and simultaneous transmission, respectively. We analytically show that when the number of users goes to infinity the energy required to guarantee the required user rates can be made as small as required at the cost of a higher delay “delay-energy tradeoff”. We explicitly compute the delay under the proposed scheduling policy and discuss how delay differentiation can be achieved. We extend the results to multiband multiaccess channel. Finally, all the results can be generalized in a straightforward fashion to broadcast channel due to the Gaussian multiaccess-broadcast channel duality.

Congenital rubella syndrome and delayed manifestations

DEFF Research Database (Denmark)

Dammeyer, Jesper Herup

2010-01-01

Objective: Several hypotheses of different medical and psychological delayed manifestations among people who have congenital rubella syndrome (CRS) have been discussed. This study tests some of these hypotheses of delayed manifestations. Methods: Gathering information about 35 individuals who hav...... which people with CRS face must primarily be understood in relation to congenital deafblindness and dual sensory and communicative deprivation....... CRS and who are congenitally deafblind. Results: None of the hypotheses could be confirmed when individuals with CRS were compared to a control group of individuals who were congenital deafblind with different aetiology than CRS. Conclusions: This study concludes that those health related problems...

Compensating for telecommunication delays during robotic telerehabilitation.

Science.gov (United States)

Consoni, Leonardo J; Siqueira, Adriano A G; Krebs, Hermano I

2017-07-01

Rehabilitation robotic systems may afford better care and telerehabilitation may extend the use and benefits of robotic therapy to the home. Data transmissions over distance are bound by intrinsic communication delays which can be significant enough to deem the activity unfeasible. Here we describe an approach that combines unilateral robotic telerehabilitation and serious games. This approach has a modular and distributed design that permits different types of robots to interact without substantial code changes. We demonstrate the approach through an online multiplayer game. Two users can remotely interact with each other with no force exchanges, while a smoothing and prediction algorithm compensates motions for the delay in the Internet connection. We demonstrate that this approach can successfully compensate for data transmission delays, even when testing between the United States and Brazil. This paper presents the initial experimental results, which highlight the performance degradation with increasing delays as well as improvements provided by the proposed algorithm, and discusses planned future developments.

Helping children express grief through symbolic communication.

Science.gov (United States)

Segal, R M

1984-12-01

Communication barriers erected by grieving children delay problem resolution. Use of the expressive arts--music, art, and body movement--in symbolic communication helps them to express overwhelming feelings and cope with trauma and stress.

Hemodynamic segmentation of brain perfusion images with delay and dispersion effects using an expectation-maximization algorithm.

Directory of Open Access Journals (Sweden)

Chia-Feng Lu

Full Text Available Automatic identification of various perfusion compartments from dynamic susceptibility contrast magnetic resonance brain images can assist in clinical diagnosis and treatment of cerebrovascular diseases. The principle of segmentation methods was based on the clustering of bolus transit-time profiles to discern areas of different tissues. However, the cerebrovascular diseases may result in a delayed and dispersed local perfusion and therefore alter the hemodynamic signal profiles. Assessing the accuracy of the segmentation technique under delayed/dispersed circumstance is critical to accurately evaluate the severity of the vascular disease. In this study, we improved the segmentation method of expectation-maximization algorithm by using the results of hierarchical clustering on whitened perfusion data as initial parameters for a mixture of multivariate Gaussians model. In addition, Monte Carlo simulations were conducted to evaluate the performance of proposed method under different levels of delay, dispersion, and noise of signal profiles in tissue segmentation. The proposed method was used to classify brain tissue types using perfusion data from five normal participants, a patient with unilateral stenosis of the internal carotid artery, and a patient with moyamoya disease. Our results showed that the normal, delayed or dispersed hemodynamics can be well differentiated for patients, and therefore the local arterial input function for impaired tissues can be recognized to minimize the error when estimating the cerebral blood flow. Furthermore, the tissue in the risk of infarct and the tissue with or without the complementary blood supply from the communicating arteries can be identified.

A negentropy minimization approach to adaptive equalization for digital communication systems.

Science.gov (United States)

Choi, Sooyong; Lee, Te-Won

2004-07-01

In this paper, we introduce and investigate a new adaptive equalization method based on minimizing approximate negentropy of the estimation error for a finite-length equalizer. We consider an approximate negentropy using nonpolynomial expansions of the estimation error as a new performance criterion to improve performance of a linear equalizer based on minimizing minimum mean squared error (MMSE). Negentropy includes higher order statistical information and its minimization provides improved converge, performance and accuracy compared to traditional methods such as MMSE in terms of bit error rate (BER). The proposed negentropy minimization (NEGMIN) equalizer has two kinds of solutions, the MMSE solution and the other one, depending on the ratio of the normalization parameters. The NEGMIN equalizer has best BER performance when the ratio of the normalization parameters is properly adjusted to maximize the output power(variance) of the NEGMIN equalizer. Simulation experiments show that BER performance of the NEGMIN equalizer with the other solution than the MMSE one has similar characteristics to the adaptive minimum bit error rate (AMBER) equalizer. The main advantage of the proposed equalizer is that it needs significantly fewer training symbols than the AMBER equalizer. Furthermore, the proposed equalizer is more robust to nonlinear distortions than the MMSE equalizer.

Synchronization of an Inertial Neural Network With Time-Varying Delays and Its Application to Secure Communication.

Science.gov (United States)

Lakshmanan, Shanmugam; Prakash, Mani; Lim, Chee Peng; Rakkiyappan, Rajan; Balasubramaniam, Pagavathigounder; Nahavandi, Saeid

2018-01-01

In this paper, synchronization of an inertial neural network with time-varying delays is investigated. Based on the variable transformation method, we transform the second-order differential equations into the first-order differential equations. Then, using suitable Lyapunov-Krasovskii functionals and Jensen's inequality, the synchronization criteria are established in terms of linear matrix inequalities. Moreover, a feedback controller is designed to attain synchronization between the master and slave models, and to ensure that the error model is globally asymptotically stable. Numerical examples and simulations are presented to indicate the effectiveness of the proposed method. Besides that, an image encryption algorithm is proposed based on the piecewise linear chaotic map and the chaotic inertial neural network. The chaotic signals obtained from the inertial neural network are utilized for the encryption process. Statistical analyses are provided to evaluate the effectiveness of the proposed encryption algorithm. The results ascertain that the proposed encryption algorithm is efficient and reliable for secure communication applications.

Minimizers with discontinuous velocities for the electromagnetic variational method

International Nuclear Information System (INIS)

De Luca, Jayme

2010-01-01

The electromagnetic two-body problem has neutral differential delay equations of motion that, for generic boundary data, can have solutions with discontinuous derivatives. If one wants to use these neutral differential delay equations with arbitrary boundary data, solutions with discontinuous derivatives must be expected and allowed. Surprisingly, Wheeler-Feynman electrodynamics has a boundary value variational method for which minimizer trajectories with discontinuous derivatives are also expected, as we show here. The variational method defines continuous trajectories with piecewise defined velocities and accelerations, and electromagnetic fields defined by the Euler-Lagrange equations on trajectory points. Here we use the piecewise defined minimizers with the Lienard-Wierchert formulas to define generalized electromagnetic fields almost everywhere (but on sets of points of zero measure where the advanced/retarded velocities and/or accelerations are discontinuous). Along with this generalization we formulate the generalized absorber hypothesis that the far fields vanish asymptotically almost everywhere and show that localized orbits with far fields vanishing almost everywhere must have discontinuous velocities on sewing chains of breaking points. We give the general solution for localized orbits with vanishing far fields by solving a (linear) neutral differential delay equation for these far fields. We discuss the physics of orbits with discontinuous derivatives stressing the differences to the variational methods of classical mechanics and the existence of a spinorial four-current associated with the generalized variational electrodynamics.

Toddler Developmental Delays After Extensive Hospitalization: Primary Care Practitioner Guidelines.

Science.gov (United States)

Lehner, Dana C; Sadler, Lois S

2015-01-01

This review investigated developmental delays toddlers may encounter after a lengthy pediatric hospitalization (30 days or greater). Physical, motor, cognitive, and psychosocial development of children aged 1 to 3 years was reviewed to raise awareness of factors associated with developmental delay after extensive hospitalization. Findings from the literature suggest that neonatal and pediatric intensive care unit (NICU/PICU) graduates are most at risk for developmental delays, but even non-critical hospital stays interrupt development to some extent. Primary care practitioners (PCPs) may be able to minimize risk for delays through the use of formal developmental screening tests and parent report surveys. References and resources are described for developmental assessment to help clinicians recognize delays and to educate families about optimal toddler development interventions. Pediatric PCPs play a leading role in coordinating health and developmental services for the young child following an extensive hospital stay.

Ultrasonographic diagnosis and minimally invasive treatment of a patent urachus associated with a patent omphalomesenteric duct in a newborn

Science.gov (United States)

Bertozzi, Mirko; Recchia, Nicola; Di Cara, Giuseppe; Riccioni, Sara; Rinaldi, Victoria Elisa; Esposito, Susanna; Appignani, Antonino

2017-01-01

Abstract Rational: Patent urachus (PU) is due to an incomplete obliteration of the urachus, whereas patent omphalomesenteric duct (POMD) is due to an incomplete obliteration of the vitelline duct. These anomalies are very rarely associated with one another. We describe a case of a newborn with a PU associated with a POMD, who was diagnosed by an abdominal ultrasound (US) and laparoscopy, and managed with a minimally invasive excision. Patient concern: A 28-day-old male neonate was referred to our hospital to investigate a delay in umbilical healing, with blood-mucinous material spillage for 3 weeks prior to the referral. The baby had no symptoms and was in good general health. Diagnosis: After a thorough cleaning of the umbilical stump, a clear granuloma with a suspected fistula was evident under the seat of the ligature of the stump. An abdominal US examination revealed the formation of a full communication, starting below the umbilical stump and developing along the anterior abdominal wall that connected with the bladder dome. The US also revealed a tubular formation containing air, which was compatible with POMD, in the deepest portion of the same umbilical stump. Considering these findings, the rare diagnosis of a PU associated with a POMD duct was suspected. Interventions: The child was then hospitalized for an elective laparoscopy that confirmed the US picture, and a minimally invasive excision was performed. Outcome: The postoperative course was favorable and uneventful. Lessons: Our case underlines the importance of evaluating all persisting umbilical lesions without delay when conventional pharmacological therapies fail. Using a US as the first approach is valuable and should be supported by laparoscopy to confirm the diagnosis; a minimally invasive excision of the remnants appears to be an effective therapeutic approach. PMID:28746173

Secure communications with low-orbit spacecraft using quantum cryptography

Science.gov (United States)

Hughes, Richard J.; Buttler, William T.; Kwiat, Paul G.; Luther, Gabriel G.; Morgan, George L; Nordholt, Jane E.; Peterson, Charles G.; Simmons, Charles M.

1999-01-01

Apparatus and method for secure communication between an earth station and spacecraft. A laser outputs single pulses that are split into preceding bright pulses and delayed attenuated pulses, and polarized. A Pockels cell changes the polarization of the polarized delayed attenuated pulses according to a string of random numbers, a first polarization representing a "1," and a second polarization representing a "0." At the receiving station, a beamsplitter randomly directs the preceding bright pulses and the polarized delayed attenuated pulses onto longer and shorter paths, both terminating in a beamsplitter which directs the preceding bright pulses and a first portion of the polarized delayed attenuated pulses to a first detector, and a second portion of the polarized delayed attenuated pulses to a second detector to generate a key for secure communication between the earth station and the spacecraft.

D-leaping: Accelerating stochastic simulation algorithms for reactions with delays

International Nuclear Information System (INIS)

Bayati, Basil; Chatelain, Philippe; Koumoutsakos, Petros

2009-01-01

We propose a novel, accelerated algorithm for the approximate stochastic simulation of biochemical systems with delays. The present work extends existing accelerated algorithms by distributing, in a time adaptive fashion, the delayed reactions so as to minimize the computational effort while preserving their accuracy. The accuracy of the present algorithm is assessed by comparing its results to those of the corresponding delay differential equations for a representative biochemical system. In addition, the fluctuations produced from the present algorithm are comparable to those from an exact stochastic simulation with delays. The algorithm is used to simulate biochemical systems that model oscillatory gene expression. The results indicate that the present algorithm is competitive with existing works for several benchmark problems while it is orders of magnitude faster for certain systems of biochemical reactions.

Design and Performance of Cyclic Delay Diversity in UWB-OFDM Systems

Directory of Open Access Journals (Sweden)

Tarasak Poramate

2008-01-01

Full Text Available This paper addresses cyclic delay diversity (CDD in an ultra-wideband communication system based on orthogonal frequency division multiplexing (OFDM technique. Symbol error rate and outage probability have been derived. It is shown that with only two transmit antennas, CDD effectively improves SER performance and reduces outage probability significantly especially when the channel delay spread is short. Both simulation and analytical results agree well in all considered cases. The selection of delay times for CDD is also addressed for some special cases.

A generalized Halanay inequality on impulsive delayed dynamical systems and its applications

International Nuclear Information System (INIS)

Wu Quanjun; Zhang Hua; Xiang Lan; Zhou Jin

2012-01-01

Highlights: ► A generalized Halanay differential inequality is derived. ► By using the inequality, we can stabilize an unstable dynamical system via impulses. ► The results are applied to chaos-based secure communication systems. ► The results may develop an effective impulsive control strategy. - Abstract: The main objective of this paper is to extend previous results on Halanay inequality for impulsive delayed dynamical systems. Based on the Razumikhin technique, a generalized Halanay differential inequality on impulsive delayed dynamical systems is analytically established. Compared with some existing works, the distinctive feature of this work is that it can be used to stabilize an unstable delayed dynamical system via impulses. The generalized Halanay inequality may be applied to secure communication systems, and a numerical example is given for illustrating and interpreting the theoretical results.

Quasipolynomial Approach to Simultaneous Robust Control of Time-Delay Systems

Directory of Open Access Journals (Sweden)

Nikolaj Semenič

2014-01-01

Full Text Available A control law for retarded time-delay systems is considered, concerning infinite closed-loop spectrum assignment. An algebraic method for spectrum assignment is presented with a unique optimization algorithm for minimization of spectral abscissa and effective shaping of the chains of infinitely many closed-loop poles. Uncertainty of plant delays of a certain structure is considered in a sense of a robust simultaneous stabilization. Robust performance is achieved using mixed sensitivity design, which is incorporated into the addressed control law.

How to start a minimal access mitral valve program.

Science.gov (United States)

Hunter, Steven

2013-11-01

The seven pillars of governance established by the National Health Service in the United Kingdom provide a useful framework for the process of introducing new procedures to a hospital. Drawing from local experience, the author present guidance for institutions considering establishing a minimal access mitral valve program. The seven pillars of governance apply to the practice of minimally invasive mitral valve surgery, based on the principle of patient-centred practice. The author delineate the benefits of minimally invasive mitral valve surgery in terms of: "clinical effectiveness", including reduced length of hospital stay, "risk management effectiveness", including conversion to sternotomy and aortic dissection, "patient experience" including improved cosmesis and quicker recovery, and the effectiveness of communication, resources and strategies in the implementation of minimally invasive mitral valve surgery. Finally, the author have identified seven learning curves experienced by surgeons involved in introducing a minimal access mitral valve program. The learning curves are defined as: techniques of mitral valve repair, Transoesophageal Echocardiography-guided cannulation, incisions, instruments, visualization, aortic occlusion and cardiopulmonary bypass strategies. From local experience, the author provide advice on how to reduce the learning curves, such as practising with the specialised instruments and visualization techniques during sternotomy cases. Underpinning the NHS pillars are the principles of systems awareness, teamwork, communication, ownership and leadership, all of which are paramount to performing any surgery but more so with minimal access surgery, as will be highlighted throughout this paper.

Phrenic Arterial Injury Presenting as Delayed Hemothorax Complicating Simple Rib Fracture.

Science.gov (United States)

Ahn, Hong Joon; Lee, Jun Wan; Kim, Kun Dong; You, In Sool

2016-04-01

Delayed hemothorax after blunt torso injury is rare, but might be associated with significant morbidity and mortality. We present a case of delayed hemothorax bleeding from phrenic artery injury in a 24-year-old woman. The patient suffered from multiple rib fractures on the right side, a right hemopneumothorax, thoracic vertebral injury and a pelvic bone fracture after a fall from a fourth floor window. Delayed hemothorax associated with phrenic artery bleeding, caused by a stab injury from a fractured rib segment, was treated successfully by a minimally invasive thoracoscopic surgery. Here, we have shown that fracture of a lower rib or ribs might be accompanied by delayed massive hemothorax that can be rapidly identified and promptly managed by thoracoscopic means.

Synchronization of stochastic delayed neural networks with markovian switching and its application.

Science.gov (United States)

Tang, Yang; Fang, Jian-An; Miao, Qing-Ying

2009-02-01

In this paper, the problem of adaptive synchronization for a class of stochastic neural networks (SNNs) which involve both mixed delays and Markovian jumping parameters is investigated. The mixed delays comprise the time-varying delays and distributed delays, both of which are mode-dependent. The stochastic perturbations are described in terms of Browian motion. By the adaptive feedback technique, several sufficient criteria have been proposed to ensure the synchronization of SNNs in mean square. Moreover, the proposed adaptive feedback scheme is applied to the secure communication. Finally, the corresponding simulation results are given to demonstrate the usefulness of the main results obtained.

A Novel Scheme to Minimize Hop Count for GAF in Wireless Sensor Networks: Two-Level GAF

Directory of Open Access Journals (Sweden)

Vaibhav Soni

2015-01-01

Full Text Available In wireless sensor networks, geographic adaptive fidelity (GAF is one of the most popular energy-aware routing protocols. It conserves energy by identifying equivalence between sensors from a routing perspective and then turning off unnecessary sensors, while maintaining the connectivity of the network. Nevertheless, the traditional GAF still cannot reach the optimum energy usage since it needs more number of hops to transmit data packets to the sink. As a result, it also leads to higher packet delay. In this paper, we propose a modified version of GAF to minimize hop count for data routing, called two-level GAF (T-GAF. Furthermore, we use a generalized version of GAF called Diagonal-GAF (DGAF where two diagonal adjacent grids can also directly communicate. It has an advantage of less overhead of coordinator election based on the residual energy of sensors. Analysis and simulation results show significant improvements of the proposed work comparing to traditional GAF in the aspect of total hop count, energy consumption, total distance covered by the data packet before reaching the sink, and packet delay. As a result, compared to traditional GAF, it needs 40% to 47% less hop count and consumes 27% to 35% less energy to extend the network lifetime.

Impact of delayed information in sub-second complex systems

Science.gov (United States)

Manrique, Pedro D.; Zheng, Minzhang; Johnson Restrepo, D. Dylan; Hui, Pak Ming; Johnson, Neil F.

What happens when you slow down the delivery of information in large-scale complex systems that operate faster than the blink of an eye? This question just adopted immediate commercial, legal and political importance following U.S. regulators' decision to allow an intentional 350 microsecond delay to be added in the ultrafast network of financial exchanges. However there is still no scientific understanding available to policymakers of the potential system-wide impact of such delays. Here we take a first step in addressing this question using a minimal model of a population of competing, heterogeneous, adaptive agents which has previously been shown to produce similar statistical features to real markets. We find that while certain extreme system-level behaviors can be prevented by such delays, the duration of others is increased. This leads to a highly non-trivial relationship between delays and system-wide instabilities which warrants deeper empirical investigation. The generic nature of our model suggests there should be a fairly wide class of complex systems where such delay-driven extreme behaviors can arise, e.g. sub-second delays in brain function possibly impacting individuals' behavior, and sub-second delays in navigational systems potentially impacting the safety of driverless vehicles.

Impact of delayed information in sub-second complex systems

Directory of Open Access Journals (Sweden)

Pedro D. Manrique

Full Text Available What happens when you slow down the delivery of information in large-scale complex systems that operate faster than the blink of an eye? This question just adopted immediate commercial, legal and political importance following U.S. regulators’ decision to allow an intentional 350 microsecond delay to be added in the ultrafast network of financial exchanges. However there is still no scientific understanding available to policymakers of the potential system-wide impact of such delays. Here we take a first step in addressing this question using a minimal model of a population of competing, heterogeneous, adaptive agents which has previously been shown to produce similar statistical features to real markets. We find that while certain extreme system-level behaviors can be prevented by such delays, the duration of others is increased. This leads to a highly non-trivial relationship between delays and system-wide instabilities which warrants deeper empirical investigation. The generic nature of our model suggests there should be a fairly wide class of complex systems where such delay-driven extreme behaviors can arise, e.g. sub-second delays in brain function possibly impacting individuals’ behavior, and sub-second delays in navigational systems potentially impacting the safety of driverless vehicles. Keywords: Ultra-fast networks, Temporal perturbation, Competition, Modeling

Synthesis for robust synchronization of chaotic systems under output feedback control with multiple random delays

International Nuclear Information System (INIS)

Wen Guilin; Wang Qingguo; Lin Chong; Han Xu; Li Guangyao

2006-01-01

Synchronization under output feedback control with multiple random time delays is studied, using the paradigm in nonlinear physics-Chua's circuit. Compared with other synchronization control methods, output feedback control with multiple random delay is superior for a realistic synchronization application to secure communications. Sufficient condition for global stability of delay-dependent synchronization is established based on the LMI technique. Numerical simulations fully support the analytical approach, in spite of the random delays

Ranking of Delay Factors for Makkah’s Construction Industry

Directory of Open Access Journals (Sweden)

Al-Emad Nashwan

2017-01-01

Full Text Available This paper presents identification of significant delay factors encountered by Makkah’s construction industry using quantitative approach. A structured questionnaire developed based on literature review was verified through pilot study involved selected construction experts. Questionnaire survey was conducted amongst Makkah construction practitioners include contractors, consultants and project management consultancy. The survey managed to collect 100 valid responses which were used to rank the factors using average index approach. Results of the analysis for 10 most significant factors causing construction delay in Makkah construction industry are Difficulties in financing project by contractor, Poor coordination between parties, Shortage of manpower, Delays in producing design documents, Improper planning and scheduling of the project, Delay in progress payments, Low productivity level of labour, Poor communication between parties, Unqualified workforce and Poor contract management. This finding is helpful to Makkah construction’s community particularly projects’ stakeholders in avoiding potential delay for their future projects.

Combined supra-transorbital keyhole approach for treatment of delayed intraorbital encephalocele: A minimally invasive approach for an unusual complication of decompressive craniectomy

Science.gov (United States)

di Somma, Lucia; Iacoangeli, Maurizio; Nasi, Davide; Balercia, Paolo; Lupi, Ettore; Girotto, Riccardo; Polonara, Gabriele; Scerrati, Massimo

2016-01-01

Background: Intraorbital encephalocele is a rare entity characterized by the herniation of cerebral tissue inside the orbital cavity through a defect of the orbital roof. In patients who have experienced head trauma, intraorbital encephalocele is usually secondary to orbital roof fracture. Case Description: We describe here a case of a patient who presented an intraorbital encephalocele 2 years after severe traumatic brain injury, treated by decompressive craniectomy and subsequent autologous cranioplasty, without any evidence of orbital roof fracture. The encephalocele removal and the subsequent orbital roof reconstruction were performed by using a modification of the supraorbital keyhole approach, in which we combine an orbital osteotomy with a supraorbital minicraniotomy to facilitate view and access to both the anterior cranial fossa and orbital compartment and to preserve the already osseointegrated autologous cranioplasty. Conclusions: The peculiarities of this case are the orbital encephalocele without an orbital roof traumatic fracture, and the combined minimally invasive approach used to fix both the encephalocele and the orbital roof defect. Delayed intraorbital encephalocele is probably a complication related to an unintentional opening of the orbit during decompressive craniectomy through which the brain herniated following the restoration of physiological intracranial pressure gradients after the bone flap repositioning. The reconstruction of the orbital roof was performed by using a combined supra-transorbital minimally invasive approach aiming at achieving adequate surgical exposure while preserving the autologous cranioplasty, already osteointegrated. To the best of our knowledge, this approach has not been previously used to address intraorbital encephalocele. PMID:26862452

Communication access to businesses and organizations for people with complex communication needs.

Science.gov (United States)

Collier, Barbara; Blackstone, Sarah W; Taylor, Andrew

2012-12-01

Human rights legislation and anti-discrimination and accessibility laws exist in many countries and through international conventions and treaties. To varying degrees, these laws protect the rights of people with disabilities to full and equal access to goods and services. Yet, the accessibility requirements of people with complex communication needs (CCN) are not well represented in the existing accessibility literature. This article describes the results of surveys completed by disability service providers and individuals with CCN due to cerebral palsy, developmental delay, and acquired disabilities. It identifies accessibility requirements for people with CCN for face-to-face communication; comprehension of spoken language; telephone communication; text and print-based communication; Internet, email, and social media interactions; and written communication. Recommendations are made for communication accessibility accommodations in regulations, guidelines, and practices.

Event-Based Stabilization over Networks with Transmission Delays

Directory of Open Access Journals (Sweden)

Xiangyu Meng

2012-01-01

Full Text Available This paper investigates asymptotic stabilization for linear systems over networks based on event-driven communication. A new communication logic is proposed to reduce the feedback effort, which has some advantages over traditional ones with continuous feedback. Considering the effect of time-varying transmission delays, the criteria for the design of both the feedback gain and the event-triggering mechanism are derived to guarantee the stability and performance requirements. Finally, the proposed techniques are illustrated by an inverted pendulum system and a numerical example.

Minimally-Invasive Neural Interface for Distributed Wireless Electrocorticogram Recording Systems

Directory of Open Access Journals (Sweden)

Sun-Il Chang

2018-01-01

Full Text Available This paper presents a minimally-invasive neural interface for distributed wireless electrocorticogram (ECoG recording systems. The proposed interface equips all necessary components for ECoG recording, such as the high performance front-end integrated circuits, a fabricated flexible microelectrode array, and wireless communication inside a miniaturized custom-made platform. The multiple units of the interface systems can be deployed to cover a broad range of the target brain region and transmit signals via a built-in intra-skin communication (ISCOM module. The core integrated circuit (IC consists of 16-channel, low-power push-pull double-gated preamplifiers, in-channel successive approximation register analog-to-digital converters (SAR ADC with a single-clocked bootstrapping switch and a time-delayed control unit, an ISCOM module for wireless data transfer through the skin instead of a power-hungry RF wireless transmitter, and a monolithic voltage/current reference generator to support the aforementioned analog and mixed-signal circuit blocks. The IC was fabricated using 250 nm CMOS processes in an area of 3.2 × 0.9 mm2 and achieved the low-power operation of 2.5 µW per channel. Input-referred noise was measured as 5.62 µVrms for 10 Hz to 10 kHz and ENOB of 7.21 at 31.25 kS/s. The implemented system successfully recorded multi-channel neural activities in vivo from a primate and demonstrated modular expandability using the ISCOM with power consumption of 160 µW.

Exponential Communication Complexity Advantage from Quantum Superposition of the Direction of Communication

Science.gov (United States)

Guérin, Philippe Allard; Feix, Adrien; Araújo, Mateus; Brukner, Časlav

2016-09-01

In communication complexity, a number of distant parties have the task of calculating a distributed function of their inputs, while minimizing the amount of communication between them. It is known that with quantum resources, such as entanglement and quantum channels, one can obtain significant reductions in the communication complexity of some tasks. In this work, we study the role of the quantum superposition of the direction of communication as a resource for communication complexity. We present a tripartite communication task for which such a superposition allows for an exponential saving in communication, compared to one-way quantum (or classical) communication; the advantage also holds when we allow for protocols with bounded error probability.

A method exploiting direct communication between phasor measurement units for power system wide-area protection and control algorithms.

Science.gov (United States)

Almas, Muhammad Shoaib; Vanfretti, Luigi

2017-01-01

Synchrophasor measurements from Phasor Measurement Units (PMUs) are the primary sensors used to deploy Wide-Area Monitoring, Protection and Control (WAMPAC) systems. PMUs stream out synchrophasor measurements through the IEEE C37.118.2 protocol using TCP/IP or UDP/IP. The proposed method establishes a direct communication between two PMUs, thus eliminating the requirement of an intermediate phasor data concentrator, data mediator and/or protocol parser and thereby ensuring minimum communication latency without considering communication link delays. This method allows utilizing synchrophasor measurements internally in a PMU to deploy custom protection and control algorithms. These algorithms are deployed using protection logic equations which are supported by all the PMU vendors. Moreover, this method reduces overall equipment cost as the algorithms execute internally in a PMU and therefore does not require any additional controller for their deployment. The proposed method can be utilized for fast prototyping of wide-area measurements based protection and control applications. The proposed method is tested by coupling commercial PMUs as Hardware-in-the-Loop (HIL) with Opal-RT's eMEGAsim Real-Time Simulator (RTS). As illustrative example, anti-islanding protection application is deployed using proposed method and its performance is assessed. The essential points in the method are: •Bypassing intermediate phasor data concentrator or protocol parsers as the synchrophasors are communicated directly between the PMUs (minimizes communication delays).•Wide Area Protection and Control Algorithm is deployed using logic equations in the client PMU, therefore eliminating the requirement for an external hardware controller (cost curtailment)•Effortless means to exploit PMU measurements in an environment familiar to protection engineers.

Time-varying delays compensation algorithm for powertrain active damping of an electrified vehicle equipped with an axle motor during regenerative braking

Science.gov (United States)

Zhang, Junzhi; Li, Yutong; Lv, Chen; Gou, Jinfang; Yuan, Ye

2017-03-01

The flexibility of the electrified powertrain system elicits a negative effect upon the cooperative control performance between regenerative and hydraulic braking and the active damping control performance. Meanwhile, the connections among sensors, controllers, and actuators are realized via network communication, i.e., controller area network (CAN), that introduces time-varying delays and deteriorates the control performances of the closed-loop control systems. As such, the goal of this paper is to develop a control algorithm to cope with all these challenges. To this end, the models of the stochastic network induced time-varying delays, based on a real in-vehicle network topology and on a flexible electrified powertrain, were firstly built. In order to further enhance the control performances of active damping and cooperative control of regenerative and hydraulic braking, the time-varying delays compensation algorithm for the electrified powertrain active damping during regenerative braking was developed based on a predictive scheme. The augmented system is constructed and the H∞ performance is analyzed. Based on this analysis, the control gains are derived by solving a nonlinear minimization problem. The simulations and hardware-in-loop (HIL) tests were carried out to validate the effectiveness of the developed algorithm. The test results show that the active damping and cooperative control performances are enhanced significantly.

Use of Spatial Communication in Aphasia

Science.gov (United States)

Johnson, Sarah; Cocks, Naomi; Dipper, Lucy

2013-01-01

Background: Spatial communication consists of both verbal spatial language and gesture. There has been minimal research investigating the use of spatial communication, and even less focussing on people with aphasia.

Communication nets stochastic message flow and delay

CERN Document Server

Kleinrock, Leonard

2007-01-01

Considerable research has been devoted to the formulation and solution of problems involving flow within connected networks. Independent of these surveys, an extensive body of knowledge has accumulated on the subject of queues, particularly in regard to stochastic flow through single-node servicing facilities. This text combines studies of connected networks with those of stochastic flow, providing a basis for understanding the general behavior and operation of communication networks in realistic situations.Author Leonard Kleinrock of the Computer Science Department at UCLA created the basic p

Communication in Pipes Using Acoustic Modems that Provide Minimal Obstruction to Fluid Flow

Science.gov (United States)

Bar-Cohen, Yoseph (Inventor); Archer, Eric D. (Inventor); Bao, Xiaoqi (Inventor); Sherrit, Stewart (Inventor)

2016-01-01

A plurality of phased array acoustic communication devices are used to communicate data along a tubulation, such as a well. The phased array acoustic communication devices employ phased arrays of acoustic transducers, such as piezoelectric transducers, to direct acoustic energy in desired directions along the tubulation. The system is controlled by a computer-based controller. Information, including data and commands, is communicated using digital signaling.

Turn-taking cue delays in human-robot communication

NARCIS (Netherlands)

Cuijpers, R. H.; Van Den Goor, V. J.P.

2017-01-01

Fluent communication between a human and a robot relies on the use of effective turn-taking cues. In human speech staying silent after a sequence of utterances is usually accompanied by an explicit turnyielding cue to signal the end of a turn. Here we study the effect of the timing of four

Feasible quantum communication complexity protocol

International Nuclear Information System (INIS)

Galvao, Ernesto F.

2002-01-01

I show that a simple multiparty communication task can be performed more efficiently with quantum communication than with classical communication, even with low detection efficiency η. The task is a communication complexity problem in which distant parties need to compute a function of the distributed inputs, while minimizing the amount of communication between them. A realistic quantum optical setup is suggested that can demonstrate a five-party quantum protocol with higher-than-classical performance, provided η>0.33

Identification of fractional-order systems with time delays using block pulse functions

Science.gov (United States)

Tang, Yinggan; Li, Ning; Liu, Minmin; Lu, Yao; Wang, Weiwei

2017-07-01

In this paper, a novel method based on block pulse functions is proposed to identify continuous-time fractional-order systems with time delays. First, the operational matrices of block pulse functions for fractional integral operator and time delay operator are derived. Then, these operational matrices are applied to convert the continuous-time fractional-order systems with time delays to an algebraic equation. Finally, the system's parameters along with the differentiation orders and the time delays are all simultaneously estimated through minimizing a quadric error function. The proposed method reduces the computation complexity of the identification process, and also it does not require the system's differentiation orders to be commensurate. The effectiveness of the proposed method are demonstrated by several numerical examples.

Fusion cross sections from measurements of delayed X-rays

International Nuclear Information System (INIS)

Pacheco, A.J.; Gregorio, D.E. di; Fernandez Niello, J.O; Elgue, M.

1988-01-01

The program XRAY is a FORTRAN 77 computer code for the extraction of fusion cross sections from delayed X-ray measurements. This is accomplished by calculating the theoretical expressions of the time dependence of the evaporation-residue cross sections and taking them as adjustable parameters in a χ 2 minimization procedure. (orig.)

Minimizing Redundant Messages and Improving Search Efficiency under Highly Dynamic Mobile P2P Network

Directory of Open Access Journals (Sweden)

Ajay Arunachalam

2016-02-01

Full Text Available Resource Searching is one of the key functional tasks in large complex networks. With the P2P architecture, millions of peers connect together instantly building a communication pattern. Searching in mobile networks faces additional limitations and challenges. Flooding technique can cope up with the churn and searches aggressively by visiting almost all the nodes. But it exponentially increases the network traffic and thus does not scale well. Further the duplicated query messages consume extra battery power and network bandwidth. The blind flooding also suffers from long delay problem in P2P networks. In this paper, we propose optimal density based flooding resource discovery schemes. Our first model takes into account local graph topology information to supplement the resource discovery process while in our extended version we also consider the neighboring node topology information along with the local node information to further effectively use the mobile and network resources. Our proposed method reduces collision at the same time minimizes effect of redundant messages and failures. Overall the methods reduce network overhead, battery power consumption, query delay, routing load, MAC load and bandwidth usage while also achieving good success rate in comparison to the other techniques. We also perform a comprehensive analysis of the resource discovery schemes to verify the impact of varying node speed and different network conditions.

An alternative approach to calculating Area-Under-the-Curve (AUC) in delay discounting research.

Science.gov (United States)

Borges, Allison M; Kuang, Jinyi; Milhorn, Hannah; Yi, Richard

2016-09-01

Applied to delay discounting data, Area-Under-the-Curve (AUC) provides an atheoretical index of the rate of delay discounting. The conventional method of calculating AUC, by summing the areas of the trapezoids formed by successive delay-indifference point pairings, does not account for the fact that most delay discounting tasks scale delay pseudoexponentially, that is, time intervals between delays typically get larger as delays get longer. This results in a disproportionate contribution of indifference points at long delays to the total AUC, with minimal contribution from indifference points at short delays. We propose two modifications that correct for this imbalance via a base-10 logarithmic transformation and an ordinal scaling transformation of delays. These newly proposed indices of discounting, AUClog d and AUCor d, address the limitation of AUC while preserving a primary strength (remaining atheoretical). Re-examination of previously published data provides empirical support for both AUClog d and AUCor d . Thus, we believe theoretical and empirical arguments favor these methods as the preferred atheoretical indices of delay discounting. © 2016 Society for the Experimental Analysis of Behavior.

Hydrodynamic Cucker-Smale model with normalized communication weights and time delay

KAUST Repository

Choi, Young-Pil; Haskovec, Jan

2017-01-01

with time delayed non-local alignment forces. We resort to its Lagrangian formulation and prove the existence of its global in time classical solutions. Moreover, we derive a sufficient condition for the asymptotic flocking behavior of the solutions. Finally

Real-time minimal-bit-error probability decoding of convolutional codes

Science.gov (United States)

Lee, L.-N.

1974-01-01

A recursive procedure is derived for decoding of rate R = 1/n binary convolutional codes which minimizes the probability of the individual decoding decisions for each information bit, subject to the constraint that the decoding delay be limited to Delta branches. This new decoding algorithm is similar to, but somewhat more complex than, the Viterbi decoding algorithm. A real-time, i.e., fixed decoding delay, version of the Viterbi algorithm is also developed and used for comparison to the new algorithm on simulated channels. It is shown that the new algorithm offers advantages over Viterbi decoding in soft-decision applications, such as in the inner coding system for concatenated coding.

Real-time minimal bit error probability decoding of convolutional codes

Science.gov (United States)

Lee, L. N.

1973-01-01

A recursive procedure is derived for decoding of rate R=1/n binary convolutional codes which minimizes the probability of the individual decoding decisions for each information bit subject to the constraint that the decoding delay be limited to Delta branches. This new decoding algorithm is similar to, but somewhat more complex than, the Viterbi decoding algorithm. A real-time, i.e. fixed decoding delay, version of the Viterbi algorithm is also developed and used for comparison to the new algorithm on simulated channels. It is shown that the new algorithm offers advantages over Viterbi decoding in soft-decision applications such as in the inner coding system for concatenated coding.

Chaos and its synchronization in two-neuron systems with discrete delays

International Nuclear Information System (INIS)

Zhou Shangbo; Liao Xiaofeng; Yu Juebang; Wong Kwokwo

2004-01-01

It is well known that complex dynamic behaviors exist in time-delayed neural systems. Infinite positive Lyapunov exponents can be found in time-delayed chaotic systems since the dimension of such systems is infinite. However, theoretical and experimental models studied thus far are low dimensional systems with only one positive Lyapunov exponent. Consequently, messages masked by such chaotic systems are shown to be easily extracted in some cases. Therefore, communication system with a higher security level can be design by means of the time-delayed neuron systems. In this paper, we firstly investigate the dynamical behaviors of two-neuron systems with discrete delays. Then, the chaos synchronization in time-delayed neuron system is studied based on the method of designing the coupled system and employing Krasovskii-Lyapunov theory to search the synchronization conditions. Numerical results illustrate the correctness of our theoretical analyses

Introduction to Focus Issue: Time-delay dynamics

Science.gov (United States)

Erneux, Thomas; Javaloyes, Julien; Wolfrum, Matthias; Yanchuk, Serhiy

2017-11-01

The field of dynamical systems with time delay is an active research area that connects practically all scientific disciplines including mathematics, physics, engineering, biology, neuroscience, physiology, economics, and many others. This Focus Issue brings together contributions from both experimental and theoretical groups and emphasizes a large variety of applications. In particular, lasers and optoelectronic oscillators subject to time-delayed feedbacks have been explored by several authors for their specific dynamical output, but also because they are ideal test-beds for experimental studies of delay induced phenomena. Topics include the control of cavity solitons, as light spots in spatially extended systems, new devices for chaos communication or random number generation, higher order locking phenomena between delay and laser oscillation period, and systematic bifurcation studies of mode-locked laser systems. Moreover, two original theoretical approaches are explored for the so-called Low Frequency Fluctuations, a particular chaotical regime in laser output which has attracted a lot of interest for more than 30 years. Current hot problems such as the synchronization properties of networks of delay-coupled units, novel stabilization techniques, and the large delay limit of a delay differential equation are also addressed in this special issue. In addition, analytical and numerical tools for bifurcation problems with or without noise and two reviews on concrete questions are proposed. The first review deals with the rich dynamics of simple delay climate models for El Nino Southern Oscillations, and the second review concentrates on neuromorphic photonic circuits where optical elements are used to emulate spiking neurons. Finally, two interesting biological problems are considered in this Focus Issue, namely, multi-strain epidemic models and the interaction of glucose and insulin for more effective treatment.

Refuses and delays in the transportation by ship of radioactive material

International Nuclear Information System (INIS)

Xavier, Clarice; Sobreira, Ana Celia

2011-01-01

Some Class 7 materials can only be transported by ship, making that load and unload activities can be done in a port. In the Brazil, the port of Santos posses the most volume of cargo manipulation, and cargoes which contain radioactive material are always present with all manipulation requisites according to applicable regulations. The transport and manipulation operations of radioactive material are performed in accordance with national and international requisites but, some individuals posses yet a high risk perception according to our experience, involving members of Brazilian port authorities, the Navy and cargoes handlers at the ports. So, exist yet a high quantity of refuses and delays during the transport by ship. Therefore, a communication strategy was developed and applied, to inform the risk perception, supplying information on the very principles of ionizing radiation, legislation and uses of radiation, and so, diminishing the quantity of refuses and delays. From that initial communication strategy on, it becomes evident the necessity of training and conscience making a movement for the problem of refuses and delays be diminished

Development of a subway operation incident delay model using accelerated failure time approaches.

Science.gov (United States)

Weng, Jinxian; Zheng, Yang; Yan, Xuedong; Meng, Qiang

2014-12-01

This study aims to develop a subway operational incident delay model using the parametric accelerated time failure (AFT) approach. Six parametric AFT models including the log-logistic, lognormal and Weibull models, with fixed and random parameters are built based on the Hong Kong subway operation incident data from 2005 to 2012, respectively. In addition, the Weibull model with gamma heterogeneity is also considered to compare the model performance. The goodness-of-fit test results show that the log-logistic AFT model with random parameters is most suitable for estimating the subway incident delay. First, the results show that a longer subway operation incident delay is highly correlated with the following factors: power cable failure, signal cable failure, turnout communication disruption and crashes involving a casualty. Vehicle failure makes the least impact on the increment of subway operation incident delay. According to these results, several possible measures, such as the use of short-distance and wireless communication technology (e.g., Wifi and Zigbee) are suggested to shorten the delay caused by subway operation incidents. Finally, the temporal transferability test results show that the developed log-logistic AFT model with random parameters is stable over time. Copyright © 2014 Elsevier Ltd. All rights reserved.

A data analysis method for identifying deterministic components of stable and unstable time-delayed systems with colored noise

Energy Technology Data Exchange (ETDEWEB)

Patanarapeelert, K. [Faculty of Science, Department of Mathematics, Mahidol University, Rama VI Road, Bangkok 10400 (Thailand); Frank, T.D. [Institute for Theoretical Physics, University of Muenster, Wilhelm-Klemm-Str. 9, 48149 Muenster (Germany)]. E-mail: tdfrank@uni-muenster.de; Friedrich, R. [Institute for Theoretical Physics, University of Muenster, Wilhelm-Klemm-Str. 9, 48149 Muenster (Germany); Beek, P.J. [Faculty of Human Movement Sciences and Institute for Fundamental and Clinical Human Movement Sciences, Vrije Universiteit, Van der Boechorststraat 9, 1081 BT Amsterdam (Netherlands); Tang, I.M. [Faculty of Science, Department of Physics, Mahidol University, Rama VI Road, Bangkok 10400 (Thailand)

2006-12-18

A method is proposed to identify deterministic components of stable and unstable time-delayed systems subjected to noise sources with finite correlation times (colored noise). Both neutral and retarded delay systems are considered. For vanishing correlation times it is shown how to determine their noise amplitudes by minimizing appropriately defined Kullback measures. The method is illustrated by applying it to simulated data from stochastic time-delayed systems representing delay-induced bifurcations, postural sway and ship rolling.

Load Balanced Mapping of Distributed Objects to Minimize Network Communication

NARCIS (Netherlands)

Stoyenko, Alexander D.; Bosch, J.; Bosch, Jan; Aksit, Mehmet; Marlowe, Thomas J.

1996-01-01

This paper introduces a new load balancing and communica- tion minimizing heuristic used in the Inverse Remote Procedure Call (IRPC) system. While the paper briefly describes the IRPC system, the focus is on the new IRPC assignment heuristic. The IRPC compiler maps a distributed program to a graph

Asymptomatic Delayed Coil Migration from an Intracranial Aneurysm: A Case Report

Directory of Open Access Journals (Sweden)

Anirban Deep Banerjee

2011-01-01

Full Text Available Objective. To describe asymptomatic delayed migration of a coil loop in a patient following successful coil embolization of an anterior communicating artery saccular aneurysm. Methods. A 24-year-old man with a ruptured anterior communicating artery saccular aneurysm underwent coil embolization with one helical ultrasoft coil. Results. A followup CT scan head and a cerebral angiogram one month following the procedure revealed distal migration of an intra-aneurysmal coil loop into the left pericallosal artery. The patient, however, remained asymptomatic. Conclusion. Delayed migration of coil following embolization of an intracranial aneurysm is an extremely rare occurrence. An asymptomatic presentation, as in our patient, is even more unique. The stent-like configuration of the migrated spiral coil loop probably prevented complete occlusion of the blood vessel.

LHCb: Radiation hard programmable delay line for LHCb Calorimeter Upgrade

CERN Multimedia

Mauricio Ferre, J; Vilasís Cardona, X; Picatoste Olloqui, E; Machefert, F; Lefrançois, J; Duarte, O

2013-01-01

This poster describes the implementation of a SPI-programmable clock delay chip based on a Delay Locked Loop (DLL) in order to shift the phase of the LHC clock (25 ns) in steps of 1ns, with a 4ps jitter and 18ps of DNL. The delay lines will be integrated into ICECAL, the LHCb calorimeter front-end ASIC in the near future. The stringent noise requirements on the ASIC imply minimizing the noise contribution of digital components. This is accomplished by implementing the DLL in differential mode. To achieve the required radiation tolerance several techniques are applied: double guard rings between PMOS and NMOS transistors as well as glitch suppressors and TMR Registers. This 5.7 mm2 chip has been implemented in CMOS 0.35um technology.

Consensus Analysis of Second-Order Multiagent Systems with General Topology and Time Delay

Directory of Open Access Journals (Sweden)

Bo Liu

2013-01-01

Full Text Available This paper addresses the consensus of second-order multiagent systems with general topology and time delay based on the nearest neighbor rule. By using the Laplace transform technique, it is proved that the second-order multi-agent system in the presence of time-delay can reach consensus if the network topology contains a globally reachable node and time delay is bounded. The bound of time-delay only depends on eigenvalues of the Laplacian matrix of the system. The main contribution of this paper is that the accurate state of the consensus center and the upper bound of the communication delay to make the agents reach consensus are given. Some numerical simulations are given to illustrate the theoretical results.

A Simple Nod of the Head: The Effect of Minimal Robot Movements on Children's Perception of a Low-Anthropomorphic Robot

NARCIS (Netherlands)

Zaga, Cristina; de Vries, Roelof A.J.; Li, Jamy; Truong, Khiet P.; Evers, Vanessa

In this note, we present minimal robot movements for robotic technology for children. Two types of minimal gaze movements were designed: social-gaze movements to communicate social engagement and deictic-gaze movements to communicate task-related referential information. In a two (social-gaze

TTSA: An Effective Scheduling Approach for Delay Bounded Tasks in Hybrid Clouds.

Science.gov (United States)

Yuan, Haitao; Bi, Jing; Tan, Wei; Zhou, MengChu; Li, Bo Hu; Li, Jianqiang

2017-11-01

The economy of scale provided by cloud attracts a growing number of organizations and industrial companies to deploy their applications in cloud data centers (CDCs) and to provide services to users around the world. The uncertainty of arriving tasks makes it a big challenge for private CDC to cost-effectively schedule delay bounded tasks without exceeding their delay bounds. Unlike previous studies, this paper takes into account the cost minimization problem for private CDC in hybrid clouds, where the energy price of private CDC and execution price of public clouds both show the temporal diversity. Then, this paper proposes a temporal task scheduling algorithm (TTSA) to effectively dispatch all arriving tasks to private CDC and public clouds. In each iteration of TTSA, the cost minimization problem is modeled as a mixed integer linear program and solved by a hybrid simulated-annealing particle-swarm-optimization. The experimental results demonstrate that compared with the existing methods, the optimal or suboptimal scheduling strategy produced by TTSA can efficiently increase the throughput and reduce the cost of private CDC while meeting the delay bounds of all the tasks.

Computer-communication networks

CERN Document Server

Meditch, James S

1983-01-01

Computer- Communication Networks presents a collection of articles the focus of which is on the field of modeling, analysis, design, and performance optimization. It discusses the problem of modeling the performance of local area networks under file transfer. It addresses the design of multi-hop, mobile-user radio networks. Some of the topics covered in the book are the distributed packet switching queuing network design, some investigations on communication switching techniques in computer networks and the minimum hop flow assignment and routing subject to an average message delay constraint

Study of the phase delay in the amplitude-modulated harmonic oscillator

International Nuclear Information System (INIS)

Krupska, Aldona; Krupski, Marcin

2003-01-01

The delayed response of a damped harmonic oscillator (RLC circuit) to a slow periodic disturbance is presented. This communication is supplementary to the paper published recently (Krupska et al 2001 Eur. J. Phys. 22 133-8)

Time domain passivity controller for 4-channel time-delay bilateral teleoperation.

Science.gov (United States)

Rebelo, Joao; Schiele, Andre

2015-01-01

This paper presents an extension of the time-domain passivity control approach to a four-channel bilateral controller under the effects of time delays. Time-domain passivity control has been used successfully to stabilize teleoperation systems with position-force and position-position controllers; however, the performance with such control architectures is sub-optimal both with and without time delays. This work extends the network representation of the time-domain passivity controller to the four-channel architecture, which provides perfect transparency to the user without time delay. The proposed architecture is based on modelling the controllers as dependent voltage sources and using only series passivity controllers. The obtained results are shown on a one degree-of-freedom setup and illustrate the stabilization behaviour of the proposed controller when time delay is present in the communication channel.

Relationships between soldiers' PTSD symptoms and spousal communication during deployment.

Science.gov (United States)

Carter, Sarah; Loew, Benjamin; Allen, Elizabeth; Stanley, Scott; Rhoades, Galena; Markman, Howard

2011-06-01

Social support, including support from spouses, may buffer against posttraumatic stress disorder (PTSD) symptoms. The current study assessed whether the frequency of spousal communication during a recent deployment, a potentially important source of support for soldiers, was related to postdeployment PTSD symptoms. Data came from 193 married male Army soldiers who returned from military deployment within the past year. For communication modalities conceptualized as delayed (i.e., letters, care packages, and e-mails), greater spousal communication frequency during deployment was associated with lower postdeployment PTSD symptom scores, but only at higher levels of marital satisfaction (p = .009). At lower marital satisfaction, more delayed spousal communication during deployment was associated with more PTSD symptoms (p = .042). For communication modalities conceptualized as interactive (i.e., phone calls, instant messaging, instant messaging with video), the same general direction of effects was seen, but the interaction between communication frequency and marital satisfaction predicting PTSD symptoms did not reach significance. Copyright © 2011 International Society for Traumatic Stress Studies.

Exploring delay causes of road construction projects in

Directory of Open Access Journals (Sweden)

Remon F. Aziz

2016-06-01

Full Text Available Construction delays are a common phenomenon in civil engineering projects in Egypt including road construction projects. Therefore, it is essential to study and analyze causes of road construction delays. This paper studied a list of construction delay causes gathered from literature having different types of construction, different countries, different periods and different numbers of delay causes and delay groups. A questionnaire and personal interviews have formed the basis of this paper listing 293 delay causes. The questionnaire survey was distributed to 500 construction participants and 389 were received who represent consultants, contractors and site/design engineers excluding the owner representing the government in road projects as one party only. Relative Importance Index (RII is calculated and according to the highest values the top twenty and the least twenty delay causes of construction projects in Egypt are determined. A case study is analyzed and compared to the most important delay causes in the paper. The test results reveal good correlation of causes and groups between contractors and site/design engineers and between consultants and site design engineers and a somewhat low correlation between contractors and consultants. So there are no root causes that can be taking for granted to be most or least effective delay causes. Proposed model for predicting actual road construction project duration was developed; a real case study tested the accuracy of proposed model. According to the analysis of case study, the most contributing causes and groups to delays were discussed, and some future recommendations were proposed in order to control and minimize delays in road construction projects. These findings can be helpful for project managers to mitigate the road construction delays in Egypt. In order to effectively overcome the road construction delays in developing countries, suggestions are made for fundamental and large�

A Sociability-Based Routing Scheme for Delay-Tolerant Networks

Directory of Open Access Journals (Sweden)

Fabbri Flavio

2011-01-01

Full Text Available The problem of choosing the best forwarders in Delay-Tolerant Networks (DTNs is crucial for minimizing the delay in packet delivery and for keeping the amount of generated traffic under control. In this paper, we introduce sociable routing, a novel routing strategy that selects a subset of optimal forwarders among all the nodes and relies on them for an efficient delivery. The key idea is that of assigning to each network node a time-varying scalar parameter which captures its social behavior in terms of frequency and types of encounters. This sociability concept is widely discussed and mathematically formalized. Simulation results of a DTN of vehicles in urban environment, driven by real mobility traces, and employing sociable routing, is presented. Encouraging results show that sociable routing, compared to other known protocols, achieves a good compromise in terms of delay performance and amount of generated traffic.

Measurement-based Channel Characterization for 5G Wireless Communications on Campus Scenario

DEFF Research Database (Denmark)

Mi, Yang; He, Ruisi; Ai, Bo

2017-01-01

The fifth generation (5G) communication has been a hotspot of research in recent years, and both research institutions and industrial enterprises put a lot of interests for 5G communication at some new frequency bands. In this paper, we investigate the radio channels of 5G communications below 6...... GHz according to the requirements and scenarios of 5G communication. Channel measurements were conducted on campus of Beijing Jiaotong University, China at two key optional frequency bands below 6 GHz. By using the measured data, we analyzed key channel parameters at 460MHz and 3.5GHz, such as power...... delay profile, path loss exponent, shadow fading, and delay spread. The results are helpful for the 5G communication system design....

Wireless communication technologies in distribution automation

Energy Technology Data Exchange (ETDEWEB)

Takala, J. [VTT Energy, Espoo (Finland)

1996-12-31

The project examines four different wireless communication technologies: GSM short message service, NMT data calls, packet radio network, Autonet (Actionet) status message service. The targets for communication include: energy measurement, especially in the de-regulated electricity market, secondary sub-station control, fault indicators. The research concentrates on the usability of different communication technologies for different purposes. Data about response times, error rates, retry times, communication delays, costs etc. will be collected for each communication technology and comparative results will be obtained. Some field experiments and demonstrations will be made in energy measurement and distribution network remote control. The project is divided in four tasks. Each task is described briefly

Wireless communication technologies in distribution automation

Energy Technology Data Exchange (ETDEWEB)

Takala, J [VTT Energy, Espoo (Finland)

1997-12-31

The project examines four different wireless communication technologies: GSM short message service, NMT data calls, packet radio network, Autonet (Actionet) status message service. The targets for communication include: energy measurement, especially in the de-regulated electricity market, secondary sub-station control, fault indicators. The research concentrates on the usability of different communication technologies for different purposes. Data about response times, error rates, retry times, communication delays, costs etc. will be collected for each communication technology and comparative results will be obtained. Some field experiments and demonstrations will be made in energy measurement and distribution network remote control. The project is divided in four tasks. Each task is described briefly

Effects on Communicative Requesting and Speech Development of the Picture Exchange Communication System in Children with Characteristics of Autism

Science.gov (United States)

Ganz, Jennifer B.; Simpson, Richard L.

2004-01-01

Few studies on augmentative and alternative communication (AAC) systems have addressed the potential for such systems to impact word utterances in children with autism spectrum disorders (ASD). The Picture Exchange Communication System (PECS) is an AAC system designed specifically to minimize difficulties with communication skills experienced by…

Completion time reduction in instantly decodable network coding through decoding delay control

KAUST Repository

Douik, Ahmed S.; Sorour, Sameh; Alouini, Mohamed-Slim; Al-Naffouri, Tareq Y.

2014-01-01

For several years, the completion time and the decoding delay problems in Instantly Decodable Network Coding (IDNC) were considered separately and were thought to completely act against each other. Recently, some works aimed to balance the effects of these two important IDNC metrics but none of them studied a further optimization of one by controlling the other. In this paper, we study the effect of controlling the decoding delay to reduce the completion time below its currently best known solution. We first derive the decoding-delay-dependent expressions of the users' and their overall completion times. Although using such expressions to find the optimal overall completion time is NP-hard, we use a heuristic that minimizes the probability of increasing the maximum of these decoding-delay-dependent completion time expressions after each transmission through a layered control of their decoding delays. Simulation results show that this new algorithm achieves both a lower mean completion time and mean decoding delay compared to the best known heuristic for completion time reduction. The gap in performance becomes significant for harsh erasure scenarios.

Completion time reduction in instantly decodable network coding through decoding delay control

KAUST Repository

Douik, Ahmed S.

2014-12-01

For several years, the completion time and the decoding delay problems in Instantly Decodable Network Coding (IDNC) were considered separately and were thought to completely act against each other. Recently, some works aimed to balance the effects of these two important IDNC metrics but none of them studied a further optimization of one by controlling the other. In this paper, we study the effect of controlling the decoding delay to reduce the completion time below its currently best known solution. We first derive the decoding-delay-dependent expressions of the users\\' and their overall completion times. Although using such expressions to find the optimal overall completion time is NP-hard, we use a heuristic that minimizes the probability of increasing the maximum of these decoding-delay-dependent completion time expressions after each transmission through a layered control of their decoding delays. Simulation results show that this new algorithm achieves both a lower mean completion time and mean decoding delay compared to the best known heuristic for completion time reduction. The gap in performance becomes significant for harsh erasure scenarios.

Shared control on lunar spacecraft teleoperation rendezvous operations with large time delay

Science.gov (United States)

Ya-kun, Zhang; Hai-yang, Li; Rui-xue, Huang; Jiang-hui, Liu

2017-08-01

Teleoperation could be used in space on-orbit serving missions, such as object deorbits, spacecraft approaches, and automatic rendezvous and docking back-up systems. Teleoperation rendezvous and docking in lunar orbit may encounter bottlenecks for the inherent time delay in the communication link and the limited measurement accuracy of sensors. Moreover, human intervention is unsuitable in view of the partial communication coverage problem. To solve these problems, a shared control strategy for teleoperation rendezvous and docking is detailed. The control authority in lunar orbital maneuvers that involves two spacecraft as rendezvous and docking in the final phase was discussed in this paper. The predictive display model based on the relative dynamic equations is established to overcome the influence of the large time delay in communication link. We discuss and attempt to prove via consistent, ground-based simulations the relative merits of fully autonomous control mode (i.e., onboard computer-based), fully manual control (i.e., human-driven at the ground station) and shared control mode. The simulation experiments were conducted on the nine-degrees-of-freedom teleoperation rendezvous and docking simulation platform. Simulation results indicated that the shared control methods can overcome the influence of time delay effects. In addition, the docking success probability of shared control method was enhanced compared with automatic and manual modes.

Diagnostic delay among adults with pulmonary tuberculosis in a high gross domestic product per capita country: Reasons and magnitude of the problem

Directory of Open Access Journals (Sweden)

Wanis H Ibrahim

2016-01-01

Conclusions: Despite a favorable comparison to other countries, there is a substantial delay in the diagnosis of PTB in Qatar. Relevant actions including health education on TB are required to minimize this delay.

Estimation of time- and state-dependent delays and other parameters in functional differential equations

Science.gov (United States)

Murphy, K. A.

1990-01-01

A parameter estimation algorithm is developed which can be used to estimate unknown time- or state-dependent delays and other parameters (e.g., initial condition) appearing within a nonlinear nonautonomous functional differential equation. The original infinite dimensional differential equation is approximated using linear splines, which are allowed to move with the variable delay. The variable delays are approximated using linear splines as well. The approximation scheme produces a system of ordinary differential equations with nice computational properties. The unknown parameters are estimated within the approximating systems by minimizing a least-squares fit-to-data criterion. Convergence theorems are proved for time-dependent delays and state-dependent delays within two classes, which say essentially that fitting the data by using approximations will, in the limit, provide a fit to the data using the original system. Numerical test examples are presented which illustrate the method for all types of delay.

Delays in early neuropsychic development: Approaches to diagnosis

Directory of Open Access Journals (Sweden)

N. N. Zavadenko

2015-01-01

Full Text Available The population frequency of neuropsychic developmental delays in infants is estimated at nearly 10%; that of global intellectual disability (mental retardation is at 1-3%. Delayed development is denned as a substantial retardation as compared to the standard indicators in any of the basic spheres: motor, communicative, cognitive, adaptive-behavioral, and socioemotional ones. Global developmental delay is characterized by a significant lag in two or more spheres. The use of current diagnostic techniques, such as the Bayley or Griffiths scales, can provide an objective quantitative assessment of both an infant's overall development and indicators in individual spheres. At the preliminary examination stage, it is expedient to carry out a Denver developmental screening test that may be directly used in a doctor's consulting room. The causes of global developmental delay/intellectual disability in infants may be perinatal central nervous system (CNS lesions; brain malformations; intrauterine infections; intrauterine intoxications; early-onset psychoneurological diseases (neuroinfections, CNS injuries, epilepsies, autism spectrum disorders, etc.; congenital hypothyroidism; genetic diseases. Among all genetic causes of global developmental delay/intellectual disability, there are chromosomal anomalies (25-30%, monogenic diseases (metabolic diseases, neuroectodermal syndromes, diseases with predominant grey and white matter involvement. The diagnostic possibilities of current genetic methods are considered.

Schedulability-Driven Communication Synthesis for Time Triggered Embedded Systems

DEFF Research Database (Denmark)

Pop, Paul; Eles, Petru; Peng, Zebo

2006-01-01

We present an approach to static priority preemptive process scheduling for the synthesis of hard real-time distributed embedded systems where communication plays an important role. The communication model is based on a time-triggered protocol. We have developed an analysis for the communication...... delays proposing four different message scheduling policies over a time-triggered communication channel. Optimization strategies for the synthesis of communication are developed, and the four approaches to message scheduling are compared using extensive experiments...

Schedulability-Driven Communication Synthesis for Time Triggered Embedded Systems

DEFF Research Database (Denmark)

Pop, Paul; Eles, Petru; Peng, Zebo

1999-01-01

We present an approach to static priority preemptive process scheduling for the synthesis of hard real-time distributed embedded systems where communication plays an important role. The communication model is based on a time-triggered protocol. We have developed an analysis for the communication...... delays proposing four different message scheduling policies over a time-triggered communication channel. Optimization strategies for the synthesis of communication are developed, and the four approaches to message scheduling are compared using extensive experiments....

Schedulability-Driven Communication Synthesis for Time Triggered Embedded Systems

DEFF Research Database (Denmark)

Pop, Paul; Eles, Petru; Peng, Zebo

2004-01-01

We present an approach to static priority preemptive process scheduling for the synthesis of hard real-time distributed embedded systems where communication plays an important role. The communication model is based on a time-triggered protocol. We have developed an analysis for the communication...... delays with four different message scheduling policies over a time-triggered communication channel. Optimization strategies for the synthesis of communication are developed, and the four approaches to message scheduling are compared using extensive experiments....

Bio-Inspired Vision-Based Leader-Follower Formation Flying in the Presence of Delays

Directory of Open Access Journals (Sweden)

John Oyekan

2016-08-01

Full Text Available Flocking starlings at dusk are known for the mesmerizing and intricate shapes they generate, as well as how fluid these shapes change. They seem to do this effortlessly. Real-life vision-based flocking has not been achieved in micro-UAVs (micro Unmanned Aerial Vehicles to date. Towards this goal, we make three contributions in this paper: (i we used a computational approach to develop a bio-inspired architecture for vision-based Leader-Follower formation flying on two micro-UAVs. We believe that the minimal computational cost of the resulting algorithm makes it suitable for object detection and tracking during high-speed flocking; (ii we show that provided delays in the control loop of a micro-UAV are below a critical value, Kalman filter-based estimation algorithms are not required to achieve Leader-Follower formation flying; (iii unlike previous approaches, we do not use external observers, such as GPS signals or synchronized communication with flock members. These three contributions could be useful in achieving vision-based flocking in GPS-denied environments on computationally-limited agents.

Impact of wave propagation delay on latency in optical communication systems

Science.gov (United States)

Kawanishi, Tetsuya; Kanno, Atsushi; Yoshida, Yuki; Kitayama, Ken-ichi

2012-12-01

Latency is an important figure to describe performance of transmission systems for particular applications, such as data transfer for earthquake early warning, transaction for financial businesses, interactive services such as online games, etc. Latency consists of delay due to signal processing at nodes and transmitters, and of signal propagation delay due to propagation of electromagnetic waves. The lower limit of the latency in transmission systems using conventional single mode fibers (SMFs) depends on wave propagation speed in the SMFs which is slower than c. Photonic crystal fibers, holly fibers and large core fibers can have low effective refractive indices, and can transfer light faster than in SMFs. In free-space optical systems, signals propagate with the speed c, so that the latency could be smaller than in optical fibers. For example, LEO satellites would transmit data faster than optical submarine cables, when the transmission distance is longer than a few thousand kilometers. This paper will discuss combination of various transmission media to reduce negative impact of the latency, as well as applications of low-latency systems.

Axonal Conduction Delays, Brain State, and Corticogeniculate Communication.

Science.gov (United States)

Stoelzel, Carl R; Bereshpolova, Yulia; Alonso, Jose-Manuel; Swadlow, Harvey A

2017-06-28

Thalamocortical conduction times are short, but layer 6 corticothalamic axons display an enormous range of conduction times, some exceeding 40-50 ms. Here, we investigate (1) how axonal conduction times of corticogeniculate (CG) neurons are related to the visual information conveyed to the thalamus, and (2) how alert versus nonalert awake brain states affect visual processing across the spectrum of CG conduction times. In awake female Dutch-Belted rabbits, we found 58% of CG neurons to be visually responsive, and 42% to be unresponsive. All responsive CG neurons had simple, orientation-selective receptive fields, and generated sustained responses to stationary stimuli. CG axonal conduction times were strongly related to modulated firing rates (F1 values) generated by drifting grating stimuli, and their associated interspike interval distributions, suggesting a continuum of visual responsiveness spanning the spectrum of axonal conduction times. CG conduction times were also significantly related to visual response latency, contrast sensitivity (C-50 values), directional selectivity, and optimal stimulus velocity. Increasing alertness did not cause visually unresponsive CG neurons to become responsive and did not change the response linearity (F1/F0 ratios) of visually responsive CG neurons. However, for visually responsive CG neurons, increased alertness nearly doubled the modulated response amplitude to optimal visual stimulation (F1 values), significantly shortened response latency, and dramatically increased response reliability. These effects of alertness were uniform across the broad spectrum of CG axonal conduction times. SIGNIFICANCE STATEMENT Corticothalamic neurons of layer 6 send a dense feedback projection to thalamic nuclei that provide input to sensory neocortex. While sensory information reaches the cortex after brief thalamocortical axonal delays, corticothalamic axons can exhibit conduction delays of <2 ms to 40-50 ms. Here, in the corticogeniculate

A multi-radio, multi-hop ad-hoc radio communication network for Communications-Based Train Control (CBTC)

DEFF Research Database (Denmark)

Farooq, Jahanzeb; Bro, Lars; Karstensen, Rasmus Thystrup

2018-01-01

Communications-Based Train Control (CBTC) is a modern signalling system that uses radio communication to transfer train control information between train and wayside. The trackside networks in these systems are mostly based on conventional infrastructure Wi-Fi (IEEE 802.11). It means a train has...... to continuously associate (i.e. perform handshake) with the trackside Wi-Fi Access Points (AP) as it moves, which incurs communication delays. Additionally, these APs are connected to the wayside infrastructure via optical fiber cables that incurs huge costs. This paper presents a novel design in which trackside...

Swarm robotics and minimalism

Science.gov (United States)

Sharkey, Amanda J. C.

2007-09-01

Swarm Robotics (SR) is closely related to Swarm Intelligence, and both were initially inspired by studies of social insects. Their guiding principles are based on their biological inspiration and take the form of an emphasis on decentralized local control and communication. Earlier studies went a step further in emphasizing the use of simple reactive robots that only communicate indirectly through the environment. More recently SR studies have moved beyond these constraints to explore the use of non-reactive robots that communicate directly, and that can learn and represent their environment. There is no clear agreement in the literature about how far such extensions of the original principles could go. Should there be any limitations on the individual abilities of the robots used in SR studies? Should knowledge of the capabilities of social insects lead to constraints on the capabilities of individual robots in SR studies? There is a lack of explicit discussion of such questions, and researchers have adopted a variety of constraints for a variety of reasons. A simple taxonomy of swarm robotics is presented here with the aim of addressing and clarifying these questions. The taxonomy distinguishes subareas of SR based on the emphases and justifications for minimalism and individual simplicity.

Communication Networks - Analysis of jitter due to call-level fluctuations

NARCIS (Netherlands)

Mandjes, M.R.H.

2007-01-01

Abstract In communication networks used by constant bit rate applications, call-level dynamics (i.e. entering and leaving calls) lead to fluctuations in the load, and therefore also fluctuations in the delay (jitter). By intentionally delaying the packets at the destination, one can transform the

Time-to-administration in postoperative chemotherapy for colorectal cancer: does minimally-invasive surgery help?

Science.gov (United States)

Amore Bonapasta, Stefano; Checcacci, Paolo; Guerra, Francesco; Mirasolo, Vita M; Moraldi, Luca; Ferrara, Angelo; Annecchiarico, Mario; Coratti, Andrea

2016-06-01

The optimal delay in the start of chemotherapy following rectal cancer surgery has not yet been identified. However, postponed adjuvant therapy has been proven to be connected with a significant survival detriment. We aimed to investigate whether the time to initiation of adjuvant treatment can be influenced by the application of minimally invasive surgery rather than traditional open surgery. By comprehensively evaluating the available inherent literature, several factors appear to be associated with delayed postoperative chemotherapy. Some of them are strictly related to surgical short-term outcomes. Laparoscopy results in shortened length of hospital stay, reduced surgical morbidity and lower rate of wound infection compared to conventional surgery. Probably due to such advantages, the application of minimally-invasive surgery to treat rectal malignancies seems to impact favorably the possibility to start adjuvant chemotherapy within an adequate timeframe following surgical resection, with potential improvement in patient survival.

Communicative skills in treatmenting cancer

International Nuclear Information System (INIS)

Kuchay, Sanaullah

2007-01-01

Communication within oncology is a core clinical skill but one in which few oncologists or specialist cancer nurses have received much formal training. Inadequate communication may cause much distress for patients and their families, who often want considerably more information than is usually provided. Many patients leave consultations unsure about the diagnosis and prognosis, confused about the meaning of--and need for-further diagnostic tests, unclear about the management plan and uncertain about the true therapeutic intent of treatment. Additionally, communication difficulties may impede the recruitment of patients to clinical trials, delaying the introduction of efficacious new treatments into clinics

Bifurcation and stability of an improved time-delayed fluid flow model in internet congestion control

International Nuclear Information System (INIS)

Yu-Liang, Liu; Jie, Zhu; Xiao-Shu, Luo

2009-01-01

Based on the fluid flow time-delayed model proposed by Misra et al in internet congestion control, one modified time-delayed model is presented, where the influence of the communication delay on the router queue length is investigated in detail. The main advantage of the new model is that its stability domain is larger even without an extra controller. By linear stability analysis and numerical simulation, the effectiveness and feasibility of the novel model in internet congestion control are verified

Bifurcation and stability of an improved time-delayed fluid flow model in internet congestion control

Science.gov (United States)

Liu, Yu-Liang; Zhu, Jie; Luo, Xiao-Shu

2009-09-01

Based on the fluid flow time-delayed model proposed by Misra et al in internet congestion control, one modified time-delayed model is presented, where the influence of the communication delay on the router queue length is investigated in detail. The main advantage of the new model is that its stability domain is larger even without an extra controller. By linear stability analysis and numerical simulation, the effectiveness and feasibility of the novel model in internet congestion control are verified.

Culture Elements in Intercultural Communication:Phenomena and Strategies%Culture Elements in Intercultural Communication: Phenomena and Strategies

Institute of Scientific and Technical Information of China (English)

刘永安

2017-01-01

With the advancement of globalization and the"the one-belt and one-road"initiative, there is greater-than-ever need for intercultural communication in many fields. With distinguished cultures, there will be conflicts of all kinds in intercultur-al communication, which greatly hinder the intercultural communication. The research to explore the culture elements and the cultural interference is of great significance for intercultural communication. Herein, culture elements and culture interference are to be explored, and strategies and techniques to minimize cultural interference are put forward, so as to promote intercultural communication.

A packet loss compliant logic-based communication alogoritham for cooperative path following control

Digital Repository Service at National Institute of Oceanography (India)

Rego, F.; Aguiar, A.P.; Pascoal, A.M.

logic takes into account the topology of the communication network, the fact that communications are discrete, and the cost of exchanging information. We also address explicitly communication losses and bounded delays. Conditions are derived under which...

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...

An Efficient Offloading Scheme For MEC System Considering Delay and Energy Consumption

Science.gov (United States)

Sun, Yanhua; Hao, Zhe; Zhang, Yanhua

2018-01-01

With the increasing numbers of mobile devices, mobile edge computing (MEC) which provides cloud computing capabilities proximate to mobile devices in 5G networks has been envisioned as a promising paradigm to enhance users experience. In this paper, we investigate a joint consideration of delay and energy consumption offloading scheme (JCDE) for MEC system in 5G heterogeneous networks. An optimization is formulated to minimize the delay as well as energy consumption of the offloading system, which the delay and energy consumption of transmitting and calculating tasks are taken into account. We adopt an iterative greedy algorithm to solve the optimization problem. Furthermore, simulations were carried out to validate the utility and effectiveness of our proposed scheme. The effect of parameter variations on the system is analysed as well. Numerical results demonstrate delay and energy efficiency promotion of our proposed scheme compared with another paper’s scheme.

A Low-Power WLAN Communication Scheme for IoT WLAN Devices Using Wake-Up Receivers

Directory of Open Access Journals (Sweden)

Hanseul Hong

2018-01-01

Full Text Available In this paper, we propose a delay- and power-efficient, multi-user, low-power wireless local area network (WLAN communication scheme for Internet of Things (IoT WLAN devices. Extremely low-power operation is one of the key requirements of emerging IoT devices. However, the current duty-cycle-based power saving approach may incur large access delay times owing to the trade-offs between the power consumption and the access delay. In order to reduce this delay and enhance the power-saving performance, wake-up receiver-based schemes have been proposed. However, because wake-up receiver-based schemes do not consider multiuser operation in dense communication environments, large delays are inevitable in the case of multiuser operation. In order to provide extremely low-power operation and under 1-mW standby power with reduced delay, we employed the optimized multiuser transmission scheduling of IEEE 802.11ax in the proposed scheme and proper enhanced distributed channel access (EDCA parameter settings. This is with the aim to reduce the delay caused by long wake-up times, and to avoid collisions caused by simultaneous transmission in uplink multiuser scenario. By using the proposed scheme, simultaneous IoT communication with multiple mobile IoT devices is possible while providing low-power operation. Simulation results verified the outstanding delay performance of the proposed scheme.

Speech and language development in cognitively delayed children with cochlear implants.

Science.gov (United States)

Holt, Rachael Frush; Kirk, Karen Iler

2005-04-01

The primary goals of this investigation were to examine the speech and language development of deaf children with cochlear implants and mild cognitive delay and to compare their gains with those of children with cochlear implants who do not have this additional impairment. We retrospectively examined the speech and language development of 69 children with pre-lingual deafness. The experimental group consisted of 19 children with cognitive delays and no other disabilities (mean age at implantation = 38 months). The control group consisted of 50 children who did not have cognitive delays or any other identified disability. The control group was stratified by primary communication mode: half used total communication (mean age at implantation = 32 months) and the other half used oral communication (mean age at implantation = 26 months). Children were tested on a variety of standard speech and language measures and one test of auditory skill development at 6-month intervals. The results from each test were collapsed from blocks of two consecutive 6-month intervals to calculate group mean scores before implantation and at 1-year intervals after implantation. The children with cognitive delays and those without such delays demonstrated significant improvement in their speech and language skills over time on every test administered. Children with cognitive delays had significantly lower scores than typically developing children on two of the three measures of receptive and expressive language and had significantly slower rates of auditory-only sentence recognition development. Finally, there were no significant group differences in auditory skill development based on parental reports or in auditory-only or multimodal word recognition. The results suggest that deaf children with mild cognitive impairments benefit from cochlear implantation. Specifically, improvements are evident in their ability to perceive speech and in their reception and use of language. However, it may

Reducing Delay in Diagnosis: Multistage Recommendation Tracking.

Science.gov (United States)

Wandtke, Ben; Gallagher, Sarah

2017-11-01

The purpose of this study was to determine whether a multistage tracking system could improve communication between health care providers, reducing the risk of delay in diagnosis related to inconsistent communication and tracking of radiology follow-up recommendations. Unconditional recommendations for imaging follow-up of all diagnostic imaging modalities excluding mammography (n = 589) were entered into a database and tracked through a multistage tracking system for 13 months. Tracking interventions were performed for patients for whom completion of recommended follow-up imaging could not be identified 1 month after the recommendation due date. Postintervention compliance with the follow-up recommendation required examination completion or clinical closure (i.e., biopsy, limited life expectancy or death, or subspecialist referral). Baseline radiology information system checks performed 1 month after the recommendation due date revealed timely completion of 43.1% of recommended imaging studies at our institution before intervention. Three separate tracking interventions were studied, showing effectiveness between 29.0% and 57.8%. The multistage tracking system increased the examination completion rate to 70.5% (a 52% increase) and reduced the rate of unknown follow-up compliance and the associated risk of delay in diagnosis to 13.9% (a 74% decrease). Examinations completed after tracking intervention generated revenue of 4.1 times greater than the labor cost. Performing sequential radiology recommendation tracking interventions can substantially reduce the rate of unknown follow-up compliance and add value to the health system. Unknown follow-up compliance is a risk factor for delay in diagnosis, a form of preventable medical error commonly identified in malpractice claims involving radiologists and office-based practitioners.

Progress of Digital Communication Technology

Science.gov (United States)

Yamazaki, Satoshi; Asano, David K.

In wireless communications, since transmitted signals are scattered from many objects, many propagation paths with different time delays are formed. When transmitting and receiving while moving in such an environment, received signals will be affected by intricate selective fading in both the frequency and time domains. In this technical note, first, the mechanism of fading phenomena is clarified, changes in previous phase compensation technology are surveyed, and a foundation for digital wireless-communications technology is provided.

Cortical Composition Hierarchy Driven by Spine Proportion Economical Maximization or Wire Volume Minimization.

Directory of Open Access Journals (Sweden)

Jan Karbowski

2015-10-01

Full Text Available The structure and quantitative composition of the cerebral cortex are interrelated with its computational capacity. Empirical data analyzed here indicate a certain hierarchy in local cortical composition. Specifically, neural wire, i.e., axons and dendrites take each about 1/3 of cortical space, spines and glia/astrocytes occupy each about (1/3(2, and capillaries around (1/3(4. Moreover, data analysis across species reveals that these fractions are roughly brain size independent, which suggests that they could be in some sense optimal and thus important for brain function. Is there any principle that sets them in this invariant way? This study first builds a model of local circuit in which neural wire, spines, astrocytes, and capillaries are mutually coupled elements and are treated within a single mathematical framework. Next, various forms of wire minimization rule (wire length, surface area, volume, or conduction delays are analyzed, of which, only minimization of wire volume provides realistic results that are very close to the empirical cortical fractions. As an alternative, a new principle called "spine economy maximization" is proposed and investigated, which is associated with maximization of spine proportion in the cortex per spine size that yields equally good but more robust results. Additionally, a combination of wire cost and spine economy notions is considered as a meta-principle, and it is found that this proposition gives only marginally better results than either pure wire volume minimization or pure spine economy maximization, but only if spine economy component dominates. However, such a combined meta-principle yields much better results than the constraints related solely to minimization of wire length, wire surface area, and conduction delays. Interestingly, the type of spine size distribution also plays a role, and better agreement with the data is achieved for distributions with long tails. In sum, these results suggest

A low-delay 8 Kb/s backward-adaptive CELP coder

Science.gov (United States)

Neumeyer, L. G.; Leblanc, W. P.; Mahmoud, S. A.

1990-01-01

Code excited linear prediction coding is an efficient technique for compressing speech sequences. Communications quality of speech can be obtained at bit rates below 8 Kb/s. However, relatively large coding delays are necessary to buffer the input speech in order to perform the LPC analysis. A low delay 8 Kb/s CELP coder is introduced in which the short term predictor is based on past synthesized speech. A new distortion measure that improves the tracking of the formant filter is discussed. Formal listening tests showed that the performance of the backward adaptive coder is almost as good as the conventional CELP coder.

Linguistics in the Service of Communication Disorders: New Frontiers

Science.gov (United States)

Ravid, Dorit; Bar-On, Amalia; Dattner, Elitzur

2013-01-01

Linguistics and Communication Disorders are considered two different disciplines by most students and scholars in both fields as well as by researchers working in other relevant fields such as psychology and education. However, most core disorders, disabilities and delays in communicative ability directly concern language, especially in…

Communication Aspects of Hospice Care.

Science.gov (United States)

Jensen, Marvin D.

No theories of communication can minimize the crisis of dying. But those who study commmunication can suggest ways of offering comfort and dignity to the dying person. Many of these ways go beyond words, for death cannot be addressed with verbal cliches. The theoretical work from which a communication scholar draws can help hospice volunteers and…

Langevin approach to synchronization of hyperchaotic time-delay dynamics

Energy Technology Data Exchange (ETDEWEB)

Budini, Adrian A [Consejo Nacional de Investigaciones CientIficas y Tecnicas, Centro Atomico Bariloche, Av. E Bustillo Km 9.5, (8400) Bariloche (Argentina); Consortium of the Americas for Interdisciplinary Science and Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131 (United States)

2008-11-07

In this paper, we characterize the synchronization phenomenon of hyperchaotic scalar nonlinear delay dynamics in a fully-developed chaos regime. Our results rely on the observation that, in that regime, the stationary statistical properties of a class of hyperchaotic attractors can be reproduced with a linear Langevin equation, defined by replacing the nonlinear delay force by a delta-correlated noise. Therefore, the synchronization phenomenon can be analytically characterized by a set of coupled Langevin equations. We apply this formalism to study anticipated synchronization dynamics subject to external noise fluctuations as well as for characterizing the effects of parameter mismatch in a hyperchaotic communication scheme. The same procedure is applied to second-order differential delay equations associated with synchronization in electro-optical devices. In all cases, the departure with respect to perfect synchronization is measured through a similarity function. Numerical simulations in discrete maps associated with the hyperchaotic dynamics support the formalism.

Robust decentralised PI based LFC design for time delay power systems

International Nuclear Information System (INIS)

Bevrani, Hassan; Hiyama, Takashi

2008-01-01

In this paper, two robust decentralised proportional integral (PI) control designs are proposed for load frequency control (LFC) with communication delays. In both methodologies, the PI based LFC problem is reduced to a static output feedback (SOF) control synthesis for a multiple delay system. The first one is based on the optimal H ∞ control design using a linear matrix inequalities (LMI) technique. The second control design gives a suboptimal solution using a developed iterative linear matrix inequalities (ILMI) algorithm via the mixed H 2 /H ∞ control technique. The control strategies are suitable for LFC applications that usually employ PI control. The proposed control strategies are applied to a three control area power system with time delays and load disturbance to demonstrate their robustness

Fundamentals of Delayed Coking Joint Industry Project

Energy Technology Data Exchange (ETDEWEB)

Michael Volk Jr; Keith Wisecarver

2005-10-01

is 2,937,439 barrels/calendar day. These cokers produce 154,607 tons of coke per day and delayed coking accounts for 88% of the world capacity. The delayed coking charge capacity in the United States is 1,787,860 b/cd. Despite its wide commercial use, only relatively few contractors and refiners are truly knowledgeable in delayed-coking design, so that this process carries with it a ''black art'' connotation. Until recently, the expected yield from cokers was determined by a simple laboratory test on the feedstock. As a result of Tulsa University's prior related research, a process model was developed that with additional work could be used to optimize existing delayed cokers over a wide range of potential feedstocks and operating conditions. The objectives of this research program are to: utilize the current micro, batch and pilot unit facilities at The University of Tulsa to enhance the understanding of the coking process; conduct additional micro and pilot unit tests with new and in-house resids and recycles to make current optimization models more robust; conduct focused kinetic experiments to enhance the furnace tube model and to enhance liquid production while minimizing sulfur in the products; conduct detailed foaming studies to optimize the process and minimize process upsets; quantify the parameters that affect coke morphology; and to utilize the knowledge gained from the experimental and modeling studies to enhance the computer programs developed in the previous JIP for optimization of the coking process. These refined computer models will then be tested against refinery data provided by the member companies. Novel concepts will also be explored for hydrogen sulfide removal of furnace gases as well as gas injection studies to reduce over-cracking. The following deliverables are scheduled from the two projects of the three-year JIP: (1) A novel method for enhancing liquid yields from delayed cokers and data that provide insight as to

Towards minimal resources of measurement-based quantum computation

International Nuclear Information System (INIS)

Perdrix, Simon

2007-01-01

We improve the upper bound on the minimal resources required for measurement-only quantum computation (M A Nielsen 2003 Phys. Rev. A 308 96-100; D W Leung 2004 Int. J. Quantum Inform. 2 33; S Perdrix 2005 Int. J. Quantum Inform. 3 219-23). Minimizing the resources required for this model is a key issue for experimental realization of a quantum computer based on projective measurements. This new upper bound also allows one to reply in the negative to the open question presented by Perdrix (2004 Proc. Quantum Communication Measurement and Computing) about the existence of a trade-off between observable and ancillary qubits in measurement-only QC

Communication in diagnostic radiology: meeting the challenges of complexity.

Science.gov (United States)

Larson, David B; Froehle, Craig M; Johnson, Neil D; Towbin, Alexander J

2014-11-01

As patients and information flow through the imaging process, value is added step-by-step when information is acquired, interpreted, and communicated back to the referring clinician. However, radiology information systems are often plagued with communication errors and delays. This article presents theories and recommends strategies to continuously improve communication in the complex environment of modern radiology. Communication theories, methods, and systems that have proven their effectiveness in other environments can serve as models for radiology.

Memory State Feedback RMPC for Multiple Time-Delayed Uncertain Linear Systems with Input Constraints

Directory of Open Access Journals (Sweden)

Wei-Wei Qin

2014-01-01

Full Text Available This paper focuses on the problem of asymptotic stabilization for a class of discrete-time multiple time-delayed uncertain linear systems with input constraints. Then, based on the predictive control principle of receding horizon optimization, a delayed state dependent quadratic function is considered for incorporating MPC problem formulation. By developing a memory state feedback controller, the information of the delayed plant states can be taken into full consideration. The MPC problem is formulated to minimize the upper bound of infinite horizon cost that satisfies the sufficient conditions. Then, based on the Lyapunov-Krasovskii function, a delay-dependent sufficient condition in terms of linear matrix inequality (LMI can be derived to design a robust MPC algorithm. Finally, the digital simulation results prove availability of the proposed method.

The Evaluation of Factors Influencing Flights Delay at Czech International Airports

Directory of Open Access Journals (Sweden)

Martina Zámková

2015-01-01

Full Text Available The main goal of this article was examination of factors influencing flights delay at three most important international airports in Czech Republic. Data of selected Airlines operating in Czech Republic, whose flights are mainly oriented to international airports in Prague, Brno and Ostrava, were used for needs of this article. Analysis of contingency tables including Pearson chi-squared test was used for data processing. Dependences were presented in graphical form by correspondence analysis. Results from analysis showed that delay caused by technical reasons and maintenance is the most frequent in Prague as well as delay caused by high concentration of airspace, operational management and crew duty norms. Problems caused by departure delay from previous destination are significantly more frequent in Brno and Ostrava by reason of small number of alternative available aircraft. Delays caused by supplier (handling, catering, … are mostly short, in particular by reason of potential penalty. Delays caused by technical problems and necessary maintenance service last mostly longer time and are more frequently on aircraft of type Boeing. Delays of borrowed aircraft of type Airbus are more frequently caused by rental and control of this aircraft by other companies which causes communication and planning difficulties.

An Embedded System Dedicated to Intervehicle Communication Applications

Directory of Open Access Journals (Sweden)

Zhou Haiying

2010-01-01

Full Text Available To overcome system latency and network delay is essential for intervehicle communication (IVC applications such as hazard alarming and cooperative driving. This paper proposes a low-cost embedded software system dedicated to such applications. It consists of two basic component layers: an operating system, named HEROS (hybrid event-driven and real-time multitasking operating system, and a communication protocol, named CIVIC (Communication Inter Véhicule Intelligente et Coopérative. HEROS is originally designed for wireless sensor networks (WSNs. It contains a component-based resource-aware kernel and a low-latency tuple-based communication system. Moreover, it provides a configurable event-driven and/or real-time multitasking mechanism for various embedded applications. The CIVIC is an autoconfiguration cooperative IVC protocol. It merges proactive and reactive approaches to speed up and optimize location-based routing discovery with high-mobility nodes. Currently, this embedded system has been implemented and tested. The experiment results show that the new embedded system has low system latency and network delay under the principle of small resource consumption.

Channel and Timeslot Co-Scheduling with Minimal Channel Switching for Data Aggregation in MWSNs

Directory of Open Access Journals (Sweden)

Sanggil Yeoum

2017-05-01

Full Text Available Collision-free transmission and efficient data transfer between nodes can be achieved through a set of channels in multichannel wireless sensor networks (MWSNs. While using multiple channels, we have to carefully consider channel interference, channel and time slot (resources optimization, channel switching delay, and energy consumption. Since sensor nodes operate on low battery power, the energy consumed in channel switching becomes an important challenge. In this paper, we propose channel and time slot scheduling for minimal channel switching in MWSNs, while achieving efficient and collision-free transmission between nodes. The proposed scheme constructs a duty-cycled tree while reducing the amount of channel switching. As a next step, collision-free time slots are assigned to every node based on the minimal data collection delay. The experimental results demonstrate that the validity of our scheme reduces the amount of channel switching by 17.5%, reduces energy consumption for channel switching by 28%, and reduces the schedule length by 46%, as compared to the existing schemes.

Wireless communication technologies in distribution automation

Energy Technology Data Exchange (ETDEWEB)

Takala, J [VTT Energy, Espoo (Finland)

1998-08-01

The project started in mid 1995 and will be finished in 1997. The project examines four different wireless communication technologies: GSM short message service, NMT data calls, packet radio network and Autonet (Actionet) status message service. The targets for communication include: Energy measurement, especially in the de-regulated electricity market, secondary sub-station control and fault indicators. The research has been focused on the usability of different communication technologies for different purposes. Data about response times, reliability, error rates, retry times, communication delays, costs etc. has been collected about each communication technology and comparative results were analysed. Some field experiments and demonstrations will be made in energy measurement and distribution network remote control. The project is divided into four tasks. Each task is described briefly

Text-Based On-Line Conferencing: A Conceptual and Empirical Analysis Using a Minimal Prototype.

Science.gov (United States)

McCarthy, John C.; And Others

1993-01-01

Analyzes requirements for text-based online conferencing through the use of a minimal prototype. Topics discussed include prototyping with a minimal system; text-based communication; the system as a message passer versus the system as a shared data structure; and three exercises that showed how users worked with the prototype. (Contains 61…

A two-layer architecture for force-reflecting bilateral teleoperation with time delays

NARCIS (Netherlands)

Heck, D.J.F.; Saccon, A.; Nijmeijer, H.

2015-01-01

We propose a two-layer control architecture for bilateral teleoperation with communication delays. The controller is structured with an (outer) performance layer and an (inner) passivity layer. In the performance layer, any traditional controller for bilateral teleoperation can be implemented. In

Communication Complexity

Indian Academy of Sciences (India)

Jaikumar Radhakrishnan

We allow a small probability of error. Goal: minimize the total number of bits transmitted. ... using tools from combinatorics, coding theory, algebra, analysis, etc. Jaikumar Radhakrishnan. Communication .... Assume Alice and Bob know a good error correcting code. E : {0, 1}n → {0, 1}10n with distance, say, 3n. Alice.

Initial Characterization of Optical Communications with Disruption-Tolerant Network Protocols

Science.gov (United States)

Schoolcraft, Joshua; Wilson, Keith

2011-01-01

Disruption-tolerant networks (DTNs) are groups of network assets connected with a suite of communication protocol technologies designed to mitigate the effects of link delay and disruption. Application of DTN protocols to diverse groups of network resources in multiple sub-networks results in an overlay network-of-networks with autonomous data routing capability. In space environments where delay or disruption is expected, performance of this type of architecture (such as an interplanetary internet) can increase with the inclusion of new communications mediums and techniques. Space-based optical communication links are therefore an excellent building block of space DTN architectures. When compared to traditional radio frequency (RF) communications, optical systems can provide extremely power-efficient and high bandwidth links bridging sub-networks. Because optical links are more susceptible to link disruption and experience the same light-speed delays as RF, optical-enabled DTN architectures can lessen potential drawbacks and maintain the benefits of autonomous optical communications over deep space distances. These environment-driven expectations - link delay and interruption, along with asymmetric data rates - are the purpose of the proof-of-concept experiment outlined herein. In recognizing the potential of these two technologies, we report an initial experiment and characterization of the performance of a DTN-enabled space optical link. The experiment design employs a point-to-point free-space optical link configured to have asymmetric bandwidth. This link connects two networked systems running a DTN protocol implementation designed and written at JPL for use on spacecraft, and further configured for higher bandwidth performance. Comparing baseline data transmission metrics with and without periodic optical link interruptions, the experiment confirmed the DTN protocols' ability to handle real-world unexpected link outages while maintaining capability of

Delayed speech development in children: Introduction to terminology

Directory of Open Access Journals (Sweden)

M. Yu. Bobylova

2017-01-01

Full Text Available There has been recently an increase in the number of children diagnosed with delayed speech development. There is delay compensation with age, but mild deficiency often remains for life. Delayed speech development is more common in boys than in girls. Its etiology is unknown in most cases, so a child should be followed up to make an accurate diagnosis. Genetic predisposition or environmental factors frequently influence speech development. The course of its delays is various. In the history of a number of disorders (childhood disintegrative disorder, Landau–Kleffner syndrome, there is evidence for the normal development of speech to a certain period and then stops or even regresses. By way of comparison, there are generally speech developmental changes in autism even during the preverbal stage (a complex of revival fails to form; babbling is poor, low emotional, gibberish; at the same time, the baby recipes whole phrases without using them to communicate. These speech disorders are considered not only as a delay, but also as a developmental abnormality. Speech disorders in children should be diagnosed as early as possible in order to initiative corrective measures in time. In this case, a physician makes a diagnosis and a special education teacher does corrective work. The successful collaboration and mutual understanding of the specialists in these areas will determine quality of life for a child in the future. This paper focusses on the terminology and classification of delays, which are necessary for physicians and teachers to speak the same language.

Operation Modes and Control Schemes for Internet-Based Teleoperation System with Time Delay

Institute of Scientific and Technical Information of China (English)

曾庆军; 宋爱国

2003-01-01

Teleoperation system plays an important role in executing task under hazard environment. As the computer networks such as the Internet are being used as the communication channel of teleoperation system, varying time delay causes the overall system unstable and reduces the performance of transparency. This paper proposed twelve operation modes with different control schemes for teleoperation on the Internet with time delay. And an optimal operation mode with control scheme was specified for teleoperation with time delay, based on the tradeoff between passivity and transparency properties. It experimentally confirmed the validity of the proposed optimal mode and control scheme by using a simple one DOF master-slave manipulator system.

Modeling delay in genetic networks: from delay birth-death processes to delay stochastic differential equations.

Science.gov (United States)

Gupta, Chinmaya; López, José Manuel; Azencott, Robert; Bennett, Matthew R; Josić, Krešimir; Ott, William

2014-05-28

Delay is an important and ubiquitous aspect of many biochemical processes. For example, delay plays a central role in the dynamics of genetic regulatory networks as it stems from the sequential assembly of first mRNA and then protein. Genetic regulatory networks are therefore frequently modeled as stochastic birth-death processes with delay. Here, we examine the relationship between delay birth-death processes and their appropriate approximating delay chemical Langevin equations. We prove a quantitative bound on the error between the pathwise realizations of these two processes. Our results hold for both fixed delay and distributed delay. Simulations demonstrate that the delay chemical Langevin approximation is accurate even at moderate system sizes. It captures dynamical features such as the oscillatory behavior in negative feedback circuits, cross-correlations between nodes in a network, and spatial and temporal information in two commonly studied motifs of metastability in biochemical systems. Overall, these results provide a foundation for using delay stochastic differential equations to approximate the dynamics of birth-death processes with delay.

Modeling delay in genetic networks: From delay birth-death processes to delay stochastic differential equations

Energy Technology Data Exchange (ETDEWEB)

Gupta, Chinmaya; López, José Manuel; Azencott, Robert; Ott, William [Department of Mathematics, University of Houston, Houston, Texas 77004 (United States); Bennett, Matthew R. [Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77204, USA and Institute of Biosciences and Bioengineering, Rice University, Houston, Texas 77005 (United States); Josić, Krešimir [Department of Mathematics, University of Houston, Houston, Texas 77004 (United States); Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204 (United States)

2014-05-28

Delay is an important and ubiquitous aspect of many biochemical processes. For example, delay plays a central role in the dynamics of genetic regulatory networks as it stems from the sequential assembly of first mRNA and then protein. Genetic regulatory networks are therefore frequently modeled as stochastic birth-death processes with delay. Here, we examine the relationship between delay birth-death processes and their appropriate approximating delay chemical Langevin equations. We prove a quantitative bound on the error between the pathwise realizations of these two processes. Our results hold for both fixed delay and distributed delay. Simulations demonstrate that the delay chemical Langevin approximation is accurate even at moderate system sizes. It captures dynamical features such as the oscillatory behavior in negative feedback circuits, cross-correlations between nodes in a network, and spatial and temporal information in two commonly studied motifs of metastability in biochemical systems. Overall, these results provide a foundation for using delay stochastic differential equations to approximate the dynamics of birth-death processes with delay.

Modeling delay in genetic networks: From delay birth-death processes to delay stochastic differential equations

International Nuclear Information System (INIS)

Gupta, Chinmaya; López, José Manuel; Azencott, Robert; Ott, William; Bennett, Matthew R.; Josić, Krešimir

2014-01-01

Delay is an important and ubiquitous aspect of many biochemical processes. For example, delay plays a central role in the dynamics of genetic regulatory networks as it stems from the sequential assembly of first mRNA and then protein. Genetic regulatory networks are therefore frequently modeled as stochastic birth-death processes with delay. Here, we examine the relationship between delay birth-death processes and their appropriate approximating delay chemical Langevin equations. We prove a quantitative bound on the error between the pathwise realizations of these two processes. Our results hold for both fixed delay and distributed delay. Simulations demonstrate that the delay chemical Langevin approximation is accurate even at moderate system sizes. It captures dynamical features such as the oscillatory behavior in negative feedback circuits, cross-correlations between nodes in a network, and spatial and temporal information in two commonly studied motifs of metastability in biochemical systems. Overall, these results provide a foundation for using delay stochastic differential equations to approximate the dynamics of birth-death processes with delay

[Neuropsychomotor developmental delay: conceptual map, term definitions, uses and limitations].

Science.gov (United States)

Dornelas, Lílian de Fátima; Duarte, Neuza Maria de Castro; Magalhães, Lívia de Castro

2015-01-01

To retrieve the origin of the term neuropsychomotor developmental delay" (NPMD), its conceptual evolution over time, and to build a conceptual map based on literature review. A literature search was performed in the SciELO Brazil, Web of Science, Science Direct, OneFile (GALE), Pubmed (Medline), Whiley Online, and Springer databases, from January of 1940 to January of 2013, using the following keywords NPMD delay, NPMD retardation, developmental delay, and global developmental delay. A total of 71 articles were selected, which were used to build the conceptual map of the term. Of the 71 references, 55 were international and 16 national. The terms developmental delay and global developmental delay were the most frequently used in the international literature and, in Brazil, delayed NPMD was the most often used. The term developmental delay emerged in the mid 1940s, gaining momentum in the 1990 s. In Brazil, the term delayed NPMD started to be used in the 1980s, and has been frequently cited and published in the literature. Delayed development was a characteristic of 13 morbidities described in 23 references. Regarding the type of use, 19 references were found, with seven forms of use. Among the references, 34 had definitions of the term, and 16 different concepts were identified. Developmental delay is addressed in the international and national literature under different names, various applications, and heterogeneous concepts. Internationally, ways to improve communication between professionals have been indicated, with standardized definition of the term and use in very specific situations up to the fifth year of life, which was not found in Brazilian publications. Copyright © 2014 Associação de Pediatria de São Paulo. Publicado por Elsevier Editora Ltda. All rights reserved.

Time delays across saddles as a test of modified gravity

International Nuclear Information System (INIS)

Magueijo, João; Mozaffari, Ali

2013-01-01

Modified gravity theories can produce strong signals in the vicinity of the saddles of the total gravitational potential. In a sub-class of these models, this translates into diverging time delays for echoes crossing the saddles. Such models arise from the possibility that gravity might be infrared divergent or confined, and if suitably designed they are very difficult to rule out. We show that Lunar Laser Ranging during an eclipse could probe the time-delay effect within metres of the saddle, thereby proving or excluding these models. Very Large Baseline Interferometry, instead, could target delays across the Jupiter–Sun saddle. Such experiments would shed light on the infrared behaviour of gravity and examine the puzzling possibility that there might be well-hidden regions of strong gravity and even singularities inside the solar system. (fast track communication)

Direct 'delay' reductions of the Toda equation

International Nuclear Information System (INIS)

Joshi, Nalini

2009-01-01

A new direct method of obtaining reductions of the Toda equation is described. We find a canonical and complete class of all possible reductions under certain assumptions. The resulting equations are ordinary differential-difference equations, sometimes referred to as delay-differential equations. The representative equation of this class is hypothesized to be a new version of one of the classical Painleve equations. The Lax pair associated with this equation is obtained, also by reduction. (fast track communication)

Measuring Changes in Social Communication Behaviors: Preliminary Development of the Brief Observation of Social Communication Change (BOSCC)

Science.gov (United States)

Grzadzinski, Rebecca; Carr, Themba; Colombi, Costanza; McGuire, Kelly; Dufek, Sarah; Pickles, Andrew; Lord, Catherine

2016-01-01

Psychometric properties and initial validity of the Brief Observation of Social Communication Change (BOSCC), a measure of treatment-response for social-communication behaviors, are described. The BOSCC coding scheme is applied to 177 video observations of 56 young children with ASD and minimal language abilities. The BOSCC has high to excellent…

Exploring Cascading Effects of Multimodal Communication Skills in Infants with Hearing Loss

Science.gov (United States)

Roberts, Megan Y.; Hampton, Lauren H.

2018-01-01

Infants and toddlers with hearing loss (HL) are at risk for developing communicative delays that can have a substantial lasting effect. Understanding child characteristics that may be targeted in early intervention is essential to maximizing communicative outcomes in children with HL. Among the most malleable predictors of communication skills…

Is minimally invasive surgical treatment justified for severe acute necrotizing pancreatitis patients with dysfunction of two or more organ systems?

Science.gov (United States)

Šileikis, Audrius; Pečiulytė, Emilija; Misenkienė, Agnė; Klimašauskas, Andrius; Beiša, Virgilijus; Strupas, Kęstutis

2017-09-01

When minimally invasive therapy was introduced, it became possible to cure some patients without open surgery, or at least delay the operation for longer than a month. To determine the optimal timing to operate on patients with severe acute necrotizing pancreatitis based on the severity of organ insufficiency. A retrospective analysis was performed in all severe acute necrotizing pancreatitis patients treated in Vilnius University Hospital Santaros Klinikos (VUL SK) from 2007 to 2016. The patients were divided into groups based on the number of dysfunctional organ systems (one or more) and whether the minimally invasive step-up approach to treatment was used. The patients with one organ dysfunction had a delay of 35 (without the step-up approach) and 36 (with the step-up approach) days before the open surgery, while the patients with two or more organ systems' dysfunction had almost an identical delay of 28 days, using both surgical treatment methods. The mortality of the patients who had one organ dysfunction and in whom the step-up approach was used was 0%, while in patients without the step-up approach it was 41.7%. In the two or more organ systems' dysfunction group, the mortality for those treated with a step-up approach was 64.3%, and without it 70.7%. The surgical treatment should be initiated with a minimally invasive procedure. Additionally, the surgery on patients with two or more organ systems' dysfunction should not be delayed for more than one month.

Lapabot: a compact telesurgical robot system for minimally invasive surgery: part II. Telesurgery evaluation.

Science.gov (United States)

Park, Jun Woo; Lee, Duck Hee; Kim, Young Woo; Lee, Byeong Han; Jo, Yung Ho

2012-05-01

As described in Part I, the Lapabot was developed considering telesurgery from the initial design stage. The robot configuration is based on the master-slave structure in which the operator can be separated spatially from the patient. The distributed control architecture communicating through high-speed network enables remote control of surgical robot manipulators. In this work, we added network communication modules using user datagram protocol/internet protocol for implementation of the telesurgical system. For a stable network environment, a dedicated research network was adopted. To characterize the network environment, a data packet sender and a repeater whose packet length and packet structure are similar to those of the real data packet were developed. The developed system was evaluated through in-vitro and in-vivo experiments. With the developed system, we have successfully performed remote control of the Lapabot. The roundtrip time delay for the control signal ranged from 1.4 to 4.1 ms. The total time delay for the operator including image signal acquisition and transmission delays was under 333 ms. It did not impede surgical procedures. Initial evaluation results demonstrate the feasibility of the developed telesurgical system.

Minimally invasive plating osteosynthesis for mid-distal third humeral shaft fractures.

Science.gov (United States)

Lian, Kejian; Wang, Lei; Lin, Dasheng; Chen, Zhiwen

2013-08-01

Mid-distal third humeral shaft fractures can be effectively treated with minimally invasive plating osteosynthesis and intramedullary nailing (IMN). However, these 2 treatments have not been adequately compared. Forty-seven patients (47 fractures) with mid-distal third humeral shaft fractures were randomly allocated to undergo either minimally invasive plating osteosynthesis (n=24) or IMN (n=23). The 2 groups were similar in terms of fracture patterns, fracture location, age, and associated injuries. Intraoperative measurements included blood loss and operative time. Clinical outcome measurements included fracture healing, radial nerve recovery, and elbow and shoulder discomfort. Radiographic measurements included fracture alignment, time to healing, delayed union, and nonunion. Functional outcome was satisfactory in both groups. Mean American Shoulder and Elbow Surgeons score and Mayo score were both better for the minimally invasive plating osteosynthesis group than for the IMN group (98.2 vs 97.6, respectively, and 93.5 vs 94.1, respectively; Pshaft fractures. Minimally invasive plating osteosynthesis is more suitable for complex fractures, especially for radial protection and motion recovery of adjacent joints, compared with IMN for simple fractures. Copyright 2013, SLACK Incorporated.

Representative Delay Measurements (RDM: Facing the Challenge of Modern Networks

Directory of Open Access Journals (Sweden)

Joachim Fabini

2015-02-01

Full Text Available Network access technologies have evolved significantly in the last years. They deploy novel mechanisms like reactive capacity allocation and time-slotted operation to optimize overall network capacity. From a single node's perspective, such optimizations decrease network determinism and measurement repeatability. Evolving application fields like machine to machine (M2M communications or real-time gaming often have strict real-time requirements to operate correctly. Highly accurate delay measurements are necessary to monitor network compliance with application demands or to detect deviations of normal network behavior, which may be caused by network failures, misconfigurations or attacks. This paper analyzes factors that challenge active delay measurements in modern networks. It introduces the Representative Delay Measurement tool (RDM that addresses these factors and proposes solutions that conform to requirements of the recently published RFC7312. Delay measurement results acquired using RDM in live networks confirm that advanced measurement methods can significantly improve the quality of measurement samples by isolating systematic network behavior. The resulting high-quality samples are one prerequisite for accurate statistics that support proper operation of subsequent algorithms and applications.

The waste minimization program at the Feed Materials Production Center

International Nuclear Information System (INIS)

Blasdel, J.E.; Crotzer, M.E.; Gardner, R.L.; Kato, T.R.; Spradlin, C.N.

1987-01-01

A waste minimization program is being implemented at the Feed Materials Production Center to reduce the generation of uranium-contaminated wastes and to comply with existing and forthcoming regulations. Procedures and plans are described which deal with process and non-process trash, contaminated wood and metals, used metal drums, and major process wastes such as contaminated magnesium fluoride and neutralized raffinate. Waste minimization techniques used include segregation, source reduction, volume reduction, material substitution and waste/product recycle. The importance of training, communication, and incentives is also covered. 5 refs., 11 figs

Surgery for hip fractures: Does surgical delay affect outcomes?

Directory of Open Access Journals (Sweden)

Nicole Simunovic

2011-01-01

Full Text Available Hip fractures are associated with a high rate of mortality and profound temporary and sometimes permanent impairment of quality of life. Current guidelines indicate that surgeons should perform surgery for a hip fracture within 24 hours of injury because earlier surgery is associated with better functional outcome and lower rates of perioperative complications and mortality. Proponents of early treatment argue that this approach minimizes the length of time a patient is confined to bed rest, thereby reducing the risk for associated complications, such as pressure sores, deep vein thrombosis, and urinary tract infections. Those favoring delaying surgery beyond the guideline recommendations believe that this approach is required to medically optimize patients, and therefore decrease the risk for perioperative complications. Further challenges to resolving this debate is the lack of an accepted definition of what should constitute an "unacceptable delay" for hip fracture surgery and the fact that outcomes associated with surgical delay are based on observational data alone (i.e., not randomized controlled trials. The effect of preoperative timing on mortality and other patient-important outcomes across various age groups remains controversial and warrants a large randomized controlled trial to offer clear insights into the effects associated with early versus delayed surgery among hip fracture patients.

Scalable Optical-Fiber Communication Networks

Science.gov (United States)

Chow, Edward T.; Peterson, John C.

1993-01-01

Scalable arbitrary fiber extension network (SAFEnet) is conceptual fiber-optic communication network passing digital signals among variety of computers and input/output devices at rates from 200 Mb/s to more than 100 Gb/s. Intended for use with very-high-speed computers and other data-processing and communication systems in which message-passing delays must be kept short. Inherent flexibility makes it possible to match performance of network to computers by optimizing configuration of interconnections. In addition, interconnections made redundant to provide tolerance to faults.

A novel design for randomized immuno-oncology clinical trials with potentially delayed treatment effects

Directory of Open Access Journals (Sweden)

Pei He

2015-10-01

Full Text Available The semi-parametric proportional hazards model is widely adopted in randomized clinical trials with time-to-event outcomes, and the log-rank test is frequently used to detect a potential treatment effect. Immuno-oncology therapies pose unique challenges to the design of a trial as the treatment effect may be delayed, which violates the proportional hazards assumption, and the log-rank test has been shown to markedly lose power under the non-proportional hazards setting. A novel design and analysis approach for immuno-oncology trials is proposed through a piecewise treatment effect function, which is capable of detecting a potentially delayed treatment effect. The number of events required for the trial will be determined to ensure sufficient power for both the overall log-rank test without a delayed effect and the test beyond the delayed period when such a delay exists. The existence of a treatment delay is determined by a likelihood ratio test with resampling. Numerical results show that the proposed design adequately controls the Type I error rate, has a minimal loss in power under the proportional hazards setting and is markedly more powerful than the log-rank test with a delayed treatment effect.

The developmental sequence of social-communicative skills in young children with autism: a longitudinal study.

Science.gov (United States)

Wu, Chin-Chin; Chiang, Chung-Hsin

2014-05-01

To explore the different developmental trajectories of social-communicative skills in children with autism and typically developing infants, two longitudinal studies were conducted. In Study 1, we examined the developmental sequence of social-communicative skills in 26 typically developing infants when they were 9 months old and reexamined them when they were 12 and 15 months old. The results indicated a reliable developmental sequence of social-communicative skills in infants with typical development. In Study 2, we explored the emergence sequence of social-communicative skills of 23 children with autism and 23 children with developmental delay between the ages of 2 and 4 years. The results demonstrated that the developmental sequence of social-communicative skills in young children with autism and children with developmental delays was different.

The minimal curvaton-Higgs model

International Nuclear Information System (INIS)

Enqvist, Kari; Lerner, Rose N.; Helsinki Univ. and Helsinki Institute of Physics; Takahashi, Tomo

2013-10-01

We present the first full study of the minimal curvaton-Higgs (MCH) model, which is a minimal interpretation of the curvaton scenario with one real scalar coupled to the standard model Higgs boson. The standard model coupling allows the dynamics of the model to be determined in detail, including effects from the thermal background and from radiative corrections to the potential. The relevant mechanisms for curvaton decay are incomplete non-perturbative decay (delayed by thermal blocking), followed by decay via a dimension-5 non-renormalisable operator. To avoid spoiling the predictions of big bang nucleosynthesis, we find the ''bare'' curvaton mass to be m σ ≥8 x 10 4 GeV. To match observational data from Planck there is an upper limit on the curvaton-higgs coupling g, between 10 -3 and 10 -2 , depending on the mass. This is due to interactions with the thermal background. We find that typically non-Gaussianities are small but that if f NL is observed in the near future then m σ 9 GeV, depending on Hubble scale during inflation. In a thermal dark matter model, the lower bound on m σ can increase substantially. The parameter space may also be affected once the baryogenesis mechanism is specified.

Reconstruction of systems with impulses and delays from time series data

International Nuclear Information System (INIS)

Jeon, Jong-ha; Kim, Pilwon

2014-01-01

In this paper, we present an approach to identification of dynamical systems with irregular impulses and time delays. The suggested method enables one to reconstruct the underlying differential equations, using the l 1 -minimization technique in signal processing which takes advantage of the signal’s sparseness. Based on the idea that irregular impulses can be regarded as sparse error in the fitting procedure, we obtain an efficient algorithm for reconstructions that separates the regular parts of dynamics from impulsive ones. From time series data sampled from an impulsive ecological models, the suggested method restores an essential dynamics of the original systems. The method also applies to chaotic systems perturbed by intermittent impacts and successfully captures dynamics reflecting qualitative behavior independent of impacts. In addition, we can identify a time-delay Lotka–Volterra model with no prior information on delay time given, to which conventional parameter estimate methods are hardly applicable

Visual Localisation of Mobile Devices in an Indoor Environment under Network Delay Conditions

OpenAIRE

Fernández, Alberto Alonso; Fres, Omar Álvarez; Alonso, Ignacio González; Hu, Huosheng

2011-01-01

Current progresses in home automation and service robotic environment have highlighted the need to develop interoperability mechanisms that allow a standard communication between the two systems. During the development of the DHCompliant protocol, the problem of locating mobile devices in an indoor environment has been investigated. The communication of the device with the location service has been carried out to study the time delay that web services offer in front of the sockets. The import...

Oscillatory dynamics of an intravenous glucose tolerance test model with delay interval

Science.gov (United States)

Shi, Xiangyun; Kuang, Yang; Makroglou, Athena; Mokshagundam, Sriprakash; Li, Jiaxu

2017-11-01

Type 2 diabetes mellitus (T2DM) has become prevalent pandemic disease in view of the modern life style. Both diabetic population and health expenses grow rapidly according to American Diabetes Association. Detecting the potential onset of T2DM is an essential focal point in the research of diabetes mellitus. The intravenous glucose tolerance test (IVGTT) is an effective protocol to determine the insulin sensitivity, glucose effectiveness, and pancreatic β-cell functionality, through the analysis and parameter estimation of a proper differential equation model. Delay differential equations have been used to study the complex physiological phenomena including the glucose and insulin regulations. In this paper, we propose a novel approach to model the time delay in IVGTT modeling. This novel approach uses two parameters to simulate not only both discrete time delay and distributed time delay in the past interval, but also the time delay distributed in a past sub-interval. Normally, larger time delay, either a discrete or a distributed delay, will destabilize the system. However, we find that time delay over a sub-interval might not. We present analytically some basic model properties, which are desirable biologically and mathematically. We show that this relatively simple model provides good fit to fluctuating patient data sets and reveals some intriguing dynamics. Moreover, our numerical simulation results indicate that our model may remove the defect in well known Minimal Model, which often overestimates the glucose effectiveness index.

High-resolution, low-delay, and error-resilient medical ultrasound video communication using H.264/AVC over mobile WiMAX networks.

Science.gov (United States)

Panayides, Andreas; Antoniou, Zinonas C; Mylonas, Yiannos; Pattichis, Marios S; Pitsillides, Andreas; Pattichis, Constantinos S

2013-05-01

In this study, we describe an effective video communication framework for the wireless transmission of H.264/AVC medical ultrasound video over mobile WiMAX networks. Medical ultrasound video is encoded using diagnostically-driven, error resilient encoding, where quantization levels are varied as a function of the diagnostic significance of each image region. We demonstrate how our proposed system allows for the transmission of high-resolution clinical video that is encoded at the clinical acquisition resolution and can then be decoded with low-delay. To validate performance, we perform OPNET simulations of mobile WiMAX Medium Access Control (MAC) and Physical (PHY) layers characteristics that include service prioritization classes, different modulation and coding schemes, fading channels conditions, and mobility. We encode the medical ultrasound videos at the 4CIF (704 × 576) resolution that can accommodate clinical acquisition that is typically performed at lower resolutions. Video quality assessment is based on both clinical (subjective) and objective evaluations.

On the impact of information delay on location-based relaying: a markov modeling approach

DEFF Research Database (Denmark)

Nielsen, Jimmy Jessen; Olsen, Rasmus Løvenstein; Madsen, Tatiana Kozlova

2012-01-01

For centralized selection of communication relays, the necessary decision information needs to be collected from the mobile nodes by the access point (centralized decision point). In mobile scenarios, the required information collection and forwarding delays will affect the reliability of the col......For centralized selection of communication relays, the necessary decision information needs to be collected from the mobile nodes by the access point (centralized decision point). In mobile scenarios, the required information collection and forwarding delays will affect the reliability...... of the collected information and hence will influence the performance of the relay selection method. This paper analyzes this influence in the decision process for the example of a mobile location-based relay selection approach using a continuous time Markov chain model. The model is used to obtain optimal relay...

Direct cellular vs. indirect pager communication during orthopaedic surgical procedures: a prospective study.

Science.gov (United States)

Ortega, Gil R; Taksali, Sudeep; Smart, Ryan; Baumgaertner, Michael R

2009-01-01

satisfaction ratings (dependent on communication times and/or difficulties) were improved with direct cellular communication (Cell = 29 excellent, Page = 11 excellent). Intraoperative case interruptions (defined as delaying surgical progress) were more frequent with indirect page communication (10 page v. 0 cell). Our study demonstrates that direct wireless communication may be used to improve intraoperative communication and enhance patient safety. Direct wireless, cellular intraoperative communication improves communication times, communication accuracy, communication satisfaction, and minimizes intraoperative case interruption. As a result of this study, we hope to maintain our transition to direct wireless, cellular intraoperative orthopaedic communication to reduce medical errors, improve patient care, and enhance both orthopaedic surgeon and nursing efficiencies.

A Novel Energy Saving Algorithm with Frame Response Delay Constraint in IEEE 802.16e

Science.gov (United States)

Nga, Dinh Thi Thuy; Kim, Mingon; Kang, Minho

Sleep-mode operation of a Mobile Subscriber Station (MSS) in IEEE 802.16e effectively saves energy consumption; however, it induces frame response delay. In this letter, we propose an algorithm to quickly find the optimal value of the final sleep interval in sleep-mode in order to minimize energy consumption with respect to a given frame response delay constraint. The validations of our proposed algorithm through analytical results and simulation results suggest that our algorithm provide a potential guidance to energy saving.

Schedule Matters: Understanding the Relationship between Schedule Delays and Costs on Overruns

Science.gov (United States)

Majerowicz, Walt; Shinn, Stephen A.

2016-01-01

This paper examines the relationship between schedule delays and cost overruns on complex projects. It is generally accepted by many project practitioners that cost overruns are directly related to schedule delays. But what does "directly related to" actually mean? Some reasons or root causes for schedule delays and associated cost overruns are obvious, if only in hindsight. For example, unrealistic estimates, supply chain difficulties, insufficient schedule margin, technical problems, scope changes, or the occurrence of risk events can negatively impact schedule performance. Other factors driving schedule delays and cost overruns may be less obvious and more difficult to quantify. Examples of these less obvious factors include project complexity, flawed estimating assumptions, over-optimism, political factors, "black swan" events, or even poor leadership and communication. Indeed, is it even possible the schedule itself could be a source of delay and subsequent cost overrun? Through literature review, surveys of project practitioners, and the authors' own experience on NASA programs and projects, the authors will categorize and examine the various factors affecting the relationship between project schedule delays and cost growth. The authors will also propose some ideas for organizations to consider to help create an awareness of the factors which could cause or influence schedule delays and associated cost growth on complex projects.

Linear time delay methods and stability analyses of the human spine. Effects of neuromuscular reflex response.

Science.gov (United States)

Franklin, Timothy C; Granata, Kevin P; Madigan, Michael L; Hendricks, Scott L

2008-08-01

Linear stability methods were applied to a biomechanical model of the human musculoskeletal spine to investigate effects of reflex gain and reflex delay on stability. Equations of motion represented a dynamic 18 degrees-of-freedom rigid-body model with time-delayed reflexes. Optimal muscle activation levels were identified by minimizing metabolic power with the constraints of equilibrium and stability with zero reflex time delay. Muscle activation levels and associated muscle forces were used to find the delay margin, i.e., the maximum reflex delay for which the system was stable. Results demonstrated that stiffness due to antagonistic co-contraction necessary for stability declined with increased proportional reflex gain. Reflex delay limited the maximum acceptable proportional reflex gain, i.e., long reflex delay required smaller maximum reflex gain to avoid instability. As differential reflex gain increased, there was a small increase in acceptable reflex delay. However, differential reflex gain with values near intrinsic damping caused the delay margin to approach zero. Forward-dynamic simulations of the fully nonlinear time-delayed system verified the linear results. The linear methods accurately found the delay margin below which the nonlinear system was asymptotically stable. These methods may aid future investigations in the role of reflexes in musculoskeletal stability.

Associations between Toddler-Age Communication and Kindergarten-Age Self-Regulatory Skills

Science.gov (United States)

Aro, Tuija; Laakso, Marja-Leena; Määttä, Sira; Tolvanen, Asko; Poikkeus, Anna-Maija

2014-01-01

Purpose: In this study, the authors aimed at gaining understanding on the associations of different types of early language and communication profiles with later self-regulation skills by using longitudinal data from toddler age to kindergarten age. Method: Children with early language profiles representing expressive delay, broad delay (i.e.,…

Direct force-reflecting two-layer approach for passive bilateral teleoperation with time delays

NARCIS (Netherlands)

Heck, D.; Saccon, A.; Beerens, R.; Nijmeijer, H.

2018-01-01

We propose a two-layer control architecture for bilateral teleoperation with communication delays. The controller is structured with an (inner) performance layer and an (outer) passivity layer. In the performance layer, any traditional controller for bilateral teleoperation can be implemented. The

Disparities in breast cancer surgery delay: the lingering effect of race.

Science.gov (United States)

Sheppard, Vanessa B; Oppong, Bridget A; Hampton, Regina; Snead, Felicia; Horton, Sara; Hirpa, Fikru; Brathwaite, Echo J; Makambi, Kepher; Onyewu, S; Boisvert, Marc; Willey, Shawna

2015-09-01

Delays to surgical breast cancer treatment of 90 days or more may be associated with greater stage migration. We investigated racial disparities in time to receiving first surgical treatment in breast cancer patients. Insured black (56 %) and white (44 %) women with primary breast cancer completed telephone interviews regarding psychosocial (e.g., self-efficacy) and health care factors (e.g., communication). Clinical data were extracted from medical charts. Time to surgery was measured as the days between diagnosis and definitive surgical treatment. We also examined delays of more than 90 days. Unadjusted hazard ratios (HRs) examined univariate relationships between delay outcomes and covariates. Cox proportional hazard models were used for multivariate analyses. Mean time to surgery was higher in blacks (mean 47 days) than whites (mean 33 days; p = .001). Black women were less likely to receive therapy before 90 days compared to white women after adjustment for covariates (HR .58; 95 % confidence interval .44, .78). Health care process factors were nonsignificant in multivariate models. Women with shorter delay reported Internet use (vs. not) and underwent breast-conserving surgery (vs. mastectomy) (p interventions to address delay are needed.

Denials and Delays of Radioactive Material Shipments

International Nuclear Information System (INIS)

El-Shinawy, R.M.K.

2011-01-01

delays of shipments of radioactive materials forms an important issue today. Radioactive materials need to be transported using all modes of transport for use in different applications such as public health, industry, research and production of nuclear power. The transport of radioactive materials is governed by national and international regulations, which are based on the International Atomic Energy Agency (IAEA) regulations for safe transport of radioactive materials (TS-R-1). These regulations ensure high standards of safety. Recently there were increasing numbers of instances of denials and delays of shipments of radioactive materials even when complying with the regulations. The denials and delays can result in difficulties to patients and others who rely on products sterilized by radiation. Therefore there is an urgent need for a universally accepted approach to solve this problem. In response, the IAEA has formed an International Steering Committee (ISC) on denials and delays of radioactive materials. Also, it designate the National Focal Points (NFP) representative to help the ISC members and the IAEA by informing about denial operations and how they can help. The Steering Committee developed and adopted an action plan which includes the action to be taken. This plan is based on: Awareness, Training, Communication, Lobbying for marketing, Economic and Harmonization among member states. It is important to work within the mandate of the ISC and in the line of action plan on denials and delays. It identified the following network members such as: National Focal Points, Regional Coordinators, National Committee, National Representative for different modes of transport and similar bodies, Carriers, Producers and Suppliers, Different civil societies, NGO's, Ministry of transport and others.

Fault Detection for Non-Gaussian Stochastic Systems with Time-Varying Delay

Directory of Open Access Journals (Sweden)

Tao Li

2013-01-01

Full Text Available Fault detection (FD for non-Gaussian stochastic systems with time-varying delay is studied. The available information for the addressed problem is the input and the measured output probability density functions (PDFs of the system. In this framework, firstly, by constructing an augmented Lyapunov functional, which involves some slack variables and a tuning parameter, a delay-dependent condition for the existence of FD observer is derived in terms of linear matrix inequality (LMI and the fault can be detected through a threshold. Secondly, in order to improve the detection sensitivity performance, the optimal algorithm is applied to minimize the threshold value. Finally, paper-making process example is given to demonstrate the applicability of the proposed approach.

Preemptive scheduling of independent jobs on identical parallel machines subject to migration delays

NARCIS (Netherlands)

Fishkin, A.V.; Jansen, K.; Sevastyanov, S.V.; Sitters, R.A.; Leonardi, S.

2005-01-01

We present hardness and approximation results for the problem of scheduling n independent jobs on m identical parallel machines subject to a migration delay d so as to minimize the makespan. We give a sharp threshold on the value of d for which the complexity of the problem changes from polynomial

Preemptive scheduling of independent jobs on identical parallel machines subject to migration delays

NARCIS (Netherlands)

Sevastyanov, S. V.; Sitters, R. A.; Fishkin, A.V.

2010-01-01

We present hardness and approximation results for the problem of preemptive scheduling of n independent jobs on m identical parallel machines subject to a migration delay d with the objective to minimize the makespan. We give a sharp threshold on the value of d for which the complexity of the

Language ENvironment Analysis (LENA) in Phelan-McDermid Syndrome: Validity and Suggestions for Use in Minimally Verbal Children with Autism Spectrum Disorder

Science.gov (United States)

Rankine, Jacquelin; Li, Erin; Lurie, Stacey; Rieger, Hillary; Fourie, Emily; Siper, Paige M.; Wang, A. Ting; Buxbaum, Joseph D.; Kolevzon, Alexander

2017-01-01

Phelan-McDermid syndrome (PMS) is a single-locus cause of developmental delay, autism spectrum disorder, and minimal verbal abilities. There is an urgent need to identify objective outcome measures of expressive language for use in this and other minimally verbal populations. One potential tool is an automated language processor called Language…

Impact of MAC Delay on AUV Localization: Underwater Localization Based on Hyperbolic Frequency Modulation Signal.

Science.gov (United States)

Kim, Sungryul; Yoo, Younghwan

2018-01-26

Medium Access Control (MAC) delay which occurs between the anchor node's transmissions is one of the error sources in underwater localization. In particular, in AUV localization, the MAC delay significantly degrades the ranging accuracy. The Cramer-Rao Low Bound (CRLB) definition theoretically proves that the MAC delay significantly degrades the localization performance. This paper proposes underwater localization combined with multiple access technology to decouple the localization performance from the MAC delay. Towards this goal, we adopt hyperbolic frequency modulation (HFM) signal that provides multiplexing based on its good property, high-temporal correlation. Owing to the multiplexing ability of the HFM signal, the anchor nodes can transmit packets without MAC delay, i.e., simultaneous transmission is possible. In addition, the simulation results show that the simultaneous transmission is not an optional communication scheme, but essential for the localization of mobile object in underwater.

A Robust Longitudinal Control Strategy of Platoons under Model Uncertainties and Time Delays

NARCIS (Netherlands)

Chen, N.; Wang, M.; Alkim, Tom; van Arem, B.

2018-01-01

Automated vehicles are designed to free drivers from driving tasks and are expected to improve traffic safety and efficiency when connected via vehicle-to-vehicle communication, that is, connected automated vehicles (CAVs). The time delays and model uncertainties in vehicle control systems pose

Navicular stress fractures treated with minimally invasive fixation

Directory of Open Access Journals (Sweden)

Korula Mani Jacob

2013-01-01

Early intervention with minimally invasive surgery has significantly less morbidity and a reliable early return to active sports and is therefore the best option in high-performance athletes. Materials and Methods: Nine athletes with ten stress fractures of the navicular treated at our institution between April 1991 and October 2000. The mean age of the patients was 22.8 years (range 18-50 years. All patients were treated by minimally invasive screw fixation and early weight bearing mobilization without a cast. The average followup was 7 years (range 2-11 years. Results: Seven of the nine patients returned to their pre-fracture level of sporting activity at an average of 5 months (range 3-9 months. One patient returned to full sporting activity following a delay of 2 years due to an associated tibial stress fracture and one patient had an unsatisfactory result. Long term review at an average of 7 years showed that six of these eight patients who returned to sports remained symptom free with two patients experiencing minimal intermittent discomfort after prolonged activity. Conclusions: We recommend percutaneous screw fixation as a reliable, low morbidity procedure allowing early return to full sporting activity without long term complications or recurrences.

End-to-End Delay Model for Train Messaging over Public Land Mobile Networks

Directory of Open Access Journals (Sweden)

Franco Mazzenga

2017-11-01

Full Text Available Modern train control systems rely on a dedicated radio network for train to ground communications. A number of possible alternatives have been analysed to adopt the European Rail Traffic Management System/European Train Control System (ERTMS/ETCS control system on local/regional lines to improve transport capacity. Among them, a communication system based on public networks (cellular&satellite provides an interesting, effective and alternative solution to proprietary and expensive radio networks. To analyse performance of this solution, it is necessary to model the end-to-end delay and message loss to fully characterize the message transfer process from train to ground and vice versa. Starting from the results of a railway test campaign over a 300 km railway line for a cumulative 12,000 traveled km in 21 days, in this paper, we derive a statistical model for the end-to-end delay required for delivering messages. In particular, we propose a two states model allowing for reproducing the main behavioral characteristics of the end-to-end delay as observed experimentally. Model formulation has been derived after deep analysis of the recorded experimental data. When it is applied to model a realistic scenario, it allows for explicitly accounting for radio coverage characteristics, the received power level, the handover points along the line and for the serving radio technology. As an example, the proposed model is used to generate the end-to-end delay profile in a realistic scenario.

Time-delay interferometric ranging for space-borne gravitational-wave detectors

International Nuclear Information System (INIS)

Tinto, Massimo; Vallisneri, Michele; Armstrong, J.W.

2005-01-01

Space-borne interferometric gravitational-wave detectors, sensitive in the low-frequency (mHz) band, will fly in the next decade. In these detectors, the spacecraft-to-spacecraft light-travel times will necessarily be unequal and time varying, and (because of aberration) will have different values on up- and down-links. In such unequal-armlength interferometers, laser-phase noise will be canceled by taking linear combinations of the laser-phase observables measured between pairs of spacecraft, appropriately time shifted by the light propagation times along the corresponding arms. This procedure, known as time-delay interferometry (TDI), requires an accurate knowledge of the light-time delays as functions of time. Here we propose a high-accuracy technique to estimate these time delays, and we study its use in the context of the Laser Interferometer Space Antenna (LISA) mission. We refer to this ranging technique, which relies on the TDI combinations themselves, as time-delay interferometric ranging (TDIR). For every TDI combination, we show that, by minimizing the rms power in that combination (averaged over integration times ∼10 4 s) with respect to the time-delay parameters, we obtain estimates of the time delays accurate enough to cancel laser noise to a level well below the secondary noises. Thus TDIR allows the implementation of TDI without the use of dedicated interspacecraft ranging systems, with a potential simplification of the LISA design. In this paper we define the TDIR procedure formally, and we characterize its expected performance via simulations with the Synthetic LISA software package

Brief Report: Caregiver Strategy Implementation--Advancing Spoken Communication in Children Who Are Minimally Verbal

Science.gov (United States)

Shire, Stephanie Y.; Shih, Wendy; Kasari, Connie

2018-01-01

Research has demonstrated that caregivers' use of intervention strategies can support their children's social engagement and communication. However, it is not clear to what degree caregivers must master the strategies to effectively support gains in social communication, specifically, core challenges such as joint attention language (comments).…

A clock and data recovery method based on phase detector implemented by delay chain in FPGA

International Nuclear Information System (INIS)

Xie Mingpu; Wu Jie; Zhang Jie

2009-01-01

A clock and data recovery method based on charge pump PLL was developed to archive medium data rate serial digital communication with simple line transceivers. The phase detector was realized by FPGA. A delay chain was constructed by delay elements with the same fixed delay. Every output of the delay elements was latched by the VCO output clock when the input signal went through the delay chain. The latched result was used to detect the data transition, which reflected the phase difference between the input signal and the VCO output clock. The VCO control voltage was adjust by charge pump to reduce the phase difference and archive phase lock. The loop filter was a passive filter,parameters of which were calculated from parameters of the delay chain and VCO. The experimental result shows that the clock of a 64Mbps transmission was recovered with a jitter less than 200 ps. (authors)

Multicast Delayed Authentication For Streaming Synchrophasor Data in the Smart Grid.

Science.gov (United States)

Câmara, Sérgio; Anand, Dhananjay; Pillitteri, Victoria; Carmo, Luiz

2016-01-01

Multicast authentication of synchrophasor data is challenging due to the design requirements of Smart Grid monitoring systems such as low security overhead, tolerance of lossy networks, time-criticality and high data rates. In this work, we propose inf -TESLA, Infinite Timed Efficient Stream Loss-tolerant Authentication, a multicast delayed authentication protocol for communication links used to stream synchrophasor data for wide area control of electric power networks. Our approach is based on the authentication protocol TESLA but is augmented to accommodate high frequency transmissions of unbounded length. inf TESLA protocol utilizes the Dual Offset Key Chains mechanism to reduce authentication delay and computational cost associated with key chain commitment. We provide a description of the mechanism using two different modes for disclosing keys and demonstrate its security against a man-in-the-middle attack attempt. We compare our approach against the TESLA protocol in a 2-day simulation scenario, showing a reduction of 15.82% and 47.29% in computational cost, sender and receiver respectively, and a cumulative reduction in the communication overhead.

Impulsive stabilization and impulsive synchronization of discrete-time delayed neural networks.

Science.gov (United States)

Chen, Wu-Hua; Lu, Xiaomei; Zheng, Wei Xing

2015-04-01

This paper investigates the problems of impulsive stabilization and impulsive synchronization of discrete-time delayed neural networks (DDNNs). Two types of DDNNs with stabilizing impulses are studied. By introducing the time-varying Lyapunov functional to capture the dynamical characteristics of discrete-time impulsive delayed neural networks (DIDNNs) and by using a convex combination technique, new exponential stability criteria are derived in terms of linear matrix inequalities. The stability criteria for DIDNNs are independent of the size of time delay but rely on the lengths of impulsive intervals. With the newly obtained stability results, sufficient conditions on the existence of linear-state feedback impulsive controllers are derived. Moreover, a novel impulsive synchronization scheme for two identical DDNNs is proposed. The novel impulsive synchronization scheme allows synchronizing two identical DDNNs with unknown delays. Simulation results are given to validate the effectiveness of the proposed criteria of impulsive stabilization and impulsive synchronization of DDNNs. Finally, an application of the obtained impulsive synchronization result for two identical chaotic DDNNs to a secure communication scheme is presented.

Environmental risk communication in the petroleum industry

International Nuclear Information System (INIS)

Mulligan, J.

1997-01-01

The principles and practices of risk communication in the petroleum industry in Alberta were presented. In order to effectively communicate about risk, three challenges must be met: (1) the representatives of the oil company must accept the legitimacy of the public's assessment of risk, (2) the communication needs to be two-way, and (3) the risk-related issues in the community must be addressed through a process of participatory decision-making where the public is accepted as a legitimate partner. For the oil and gas companies, failing to undertake effective risk communication can lead to many problems, such as difficulties in obtaining regulatory approvals, production delays, high legal fees, and loss of public trust

Intelligent Transport Systems 80211-based Roadside-to-Vehicle Communications

CERN Document Server

Hasan, Syed Faraz; Chakraborty, Shyam

2013-01-01

Focusing on the nuts and bolts of wireless network access for computers on-board vehicles, this volume shows how in-car computerization now does much more than merely act as a glorified map-reader. Wireless communication is transforming road travel in ways previously undreamt of, allowing vehicles to “talk” to a wider network and monitor road conditions, potential delays and traffic congestion, all automatically. Toll payments can be made without opening the driver’s window on a cold day, while vehicles might themselves take active steps to avoid collisions. It is the connection between on-board computers and wireless access points, ubiquitous in most cities now, that is a key area of research. Moving vehicles transfer their communications to new points as they progress, and this causes delays, known as “handover latency.” In this book, new stochastic models are developed to map the disruption when connecting to 802.11 WLAN points. It details the application of stochastic tools to analyzing communic...

Space Link Extension (SLE) Emulation for High-Throughput Network Communication

Science.gov (United States)

Murawski, Robert W.; Tchorowski, Nicole; Golden, Bert

2014-01-01

As the data rate requirements for space communications increases, significant stress is placed not only on the wireless satellite communication links, but also on the ground networks which forward data from end-users to remote ground stations. These wide area network (WAN) connections add delay and jitter to the end-to-end satellite communication link, effects which can have significant impacts on the wireless communication link. It is imperative that any ground communication protocol can react to these effects such that the ground network does not become a bottleneck in the communication path to the satellite. In this paper, we present our SCENIC Emulation Lab testbed which was developed to test the CCSDS SLE protocol implementations proposed for use on future NASA communication networks. Our results show that in the presence of realistic levels of network delay, high-throughput SLE communication links can experience significant data rate throttling. Based on our observations, we present some insight into why this data throttling happens, and trace the probable issue back to non-optimal blocking communication which is sup-ported by the CCSDS SLE API recommended practices. These issues were presented as well to the SLE implementation developers which, based on our reports, developed a new release for SLE which we show fixes the SLE blocking issue and greatly improves the protocol throughput. In this paper, we also discuss future developments for our end-to-end emulation lab and how these improvements can be used to develop and test future space communication technologies.

Start time delays in operating room: Different perspectives

Directory of Open Access Journals (Sweden)

Babita Gupta

2011-01-01

Full Text Available Background: Healthcare expenditure is a serious concern, with escalating costs failing to meet the expectations of quality care. The treatment capacities are limited in a hospital setting and the operating rooms (ORs. Their optimal utilization is vital in efficient hospital management. Starting late means considerable wait time for staff, patients and waste of resources. We planned an audit to assess different perspectives of the residents in surgical specialities and anesthesia and OR staff nurses so as to know the causative factors of operative delay. This can help develop a practical model to decrease start time delays in operating room (ORs. Aims: An audit to assess different perspectives of the Operating room (OR staff with respect to the varied causative factors of operative delay in the OR. To aid in the development of a practical model to decrease start time delays in ORs and facilitate on-time starts at Jai Prakash Narayan Apex Trauma centre (JPNATC, All India Institute of Medical Sciences (AIIMS, New Delhi. Methods: We prepared a questionnaire seeking the five main reasons of delay as per their perspective. Results: The available data was analysed. Analysis of the data demonstrated the common causative factors in start time operative delays as: a lack of proper planning, deficiencies in team work, communication gap and limited availability of trained supporting staff. Conclusions: The preparation of the equipment and required material for the OR cases must be done well in advance. Utilization of newer technology enables timely booking and scheduling of cases. Improved inter-departmental coordination and compliance with preanesthetic instructions needs to be ensured. It is essential that the anesthesiologists perform their work promptly, well in time . and supervise the proceedings as the OR manager. This audit is a step forward in defining the need of effective OR planning for continuous quality improvement.

Prevention of delayed hydride cracking in zirconium alloys

International Nuclear Information System (INIS)

Cheadle, B.A.; Coleman, C.E.; Ambler, J.F.R.

1987-01-01

Zirconium alloys are susceptible to a mechanism for crack initiation and propagation called delayed hydride cracking. From a review of component failures and experimental results, we have developed the requirements for preventing this cracking. The important parameters for cracking are hydrogen concentration, flaws, and stress; each should be minimized. At the design and construction stages hydrogen pickup has to be controlled, quality assurance needs to be at a high enough level to ensure the absence of flaws, and residual stresses must be eliminated by careful fabrication and heat treatment

VSAT communications networks - An overview

Science.gov (United States)

Chakraborty, D.

1988-05-01

The very-small-aperture-terminal (VSAT) fixed satellite communication network is a star network in which many dispersed micro terminals attempt to send data in a packet form through a random access/time-division multiple-access (RA/TDMA) satellite channel with transmission delay. The basic concept of the VSAT and its service potential are discussed. Two classes of traffic are addressed, namely, business-oriented low-rate-data traffic and bulk data traffic of corporate networks. Satellite access, throughput, and delay are considered. The size of the network population that can be served in an RA/TDMA environment is calculated. User protocols are examined. A typical VSAT business scenario is described.

The minimal curvaton-Higgs model

Energy Technology Data Exchange (ETDEWEB)

Enqvist, Kari [Helsinki Univ. and Helsinki Institute of Physics (Finland). Physics Dept.; Lerner, Rose N. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Helsinki Univ. and Helsinki Institute of Physics (Finland). Physics Dept.; Takahashi, Tomo [Saga Univ. (Japan). Dept. of Physics

2013-10-15

We present the first full study of the minimal curvaton-Higgs (MCH) model, which is a minimal interpretation of the curvaton scenario with one real scalar coupled to the standard model Higgs boson. The standard model coupling allows the dynamics of the model to be determined in detail, including effects from the thermal background and from radiative corrections to the potential. The relevant mechanisms for curvaton decay are incomplete non-perturbative decay (delayed by thermal blocking), followed by decay via a dimension-5 non-renormalisable operator. To avoid spoiling the predictions of big bang nucleosynthesis, we find the ''bare'' curvaton mass to be m{sub {sigma}}{>=}8 x 10{sup 4} GeV. To match observational data from Planck there is an upper limit on the curvaton-higgs coupling g, between 10{sup -3} and 10{sup -2}, depending on the mass. This is due to interactions with the thermal background. We find that typically non-Gaussianities are small but that if f{sub NL} is observed in the near future then m{sub {sigma}}

Nonfragile Robust Model Predictive Control for Uncertain Constrained Systems with Time-Delay Compensation

Directory of Open Access Journals (Sweden)

Wei Jiang

2016-01-01

Full Text Available This study investigates the problem of asymptotic stabilization for a class of discrete-time linear uncertain time-delayed systems with input constraints. Parametric uncertainty is assumed to be structured, and delay is assumed to be known. In Lyapunov stability theory framework, two synthesis schemes of designing nonfragile robust model predictive control (RMPC with time-delay compensation are put forward, where the additive and the multiplicative gain perturbations are, respectively, considered. First, by designing appropriate Lyapunov-Krasovskii (L-K functions, the robust performance index is defined as optimization problems that minimize upper bounds of infinite horizon cost function. Then, to guarantee closed-loop stability, the sufficient conditions for the existence of desired nonfragile RMPC are obtained in terms of linear matrix inequalities (LMIs. Finally, two numerical examples are provided to illustrate the effectiveness of the proposed approaches.

The minimally tuned minimal supersymmetric standard model

International Nuclear Information System (INIS)

Essig, Rouven; Fortin, Jean-Francois

2008-01-01

The regions in the Minimal Supersymmetric Standard Model with the minimal amount of fine-tuning of electroweak symmetry breaking are presented for general messenger scale. No a priori relations among the soft supersymmetry breaking parameters are assumed and fine-tuning is minimized with respect to all the important parameters which affect electroweak symmetry breaking. The superpartner spectra in the minimally tuned region of parameter space are quite distinctive with large stop mixing at the low scale and negative squark soft masses at the high scale. The minimal amount of tuning increases enormously for a Higgs mass beyond roughly 120 GeV

Lumbar Spinal Stenosis Minimally Invasive Treatment with Bilateral Transpedicular Facet Augmentation System

Energy Technology Data Exchange (ETDEWEB)

Masala, Salvatore, E-mail: salva.masala@tiscali.it [Interventional Radiology and Radiotherapy, University of Rome ' Tor Vergata' , Department of Diagnostic and Molecular Imaging (Italy); Tarantino, Umberto [University of Rome ' Tor Vergata' , Department of Orthopaedics and Traumatology (Italy); Nano, Giovanni, E-mail: gionano@gmail.com [Interventional Radiology and Radiotherapy, University of Rome ' Tor Vergata' , Department of Diagnostic and Molecular Imaging (Italy); Iundusi, Riccardo [University of Rome ' Tor Vergata' , Department of Orthopaedics and Traumatology (Italy); Fiori, Roberto, E-mail: fiori.r@libero.it; Da Ros, Valerio, E-mail: valeriodaros@hotmail.com; Simonetti, Giovanni [Interventional Radiology and Radiotherapy, University of Rome ' Tor Vergata' , Department of Diagnostic and Molecular Imaging (Italy)

2013-06-15

Purpose. The purpose of this study was to evaluate the effectiveness of a new pedicle screw-based posterior dynamic stabilization device PDS Percudyn System Trade-Mark-Sign Anchor and Stabilizer (Interventional Spine Inc., Irvine, CA) as alternative minimally invasive treatment for patients with lumbar spine stenosis. Methods. Twenty-four consecutive patients (8 women, 16 men; mean age 61.8 yr) with lumbar spinal stenosis underwent implantation of the minimally invasive pedicle screw-based device for posterior dynamic stabilization. Inclusion criteria were lumbar stenosis without signs of instability, resistant to conservative treatment, and eligible to traditional surgical posterior decompression. Results. Twenty patients (83 %) progressively improved during the 1-year follow-up. Four (17 %) patients did not show any improvement and opted for surgical posterior decompression. For both responder and nonresponder patients, no device-related complications were reported. Conclusions. Minimally invasive PDS Percudyn System Trade-Mark-Sign has effectively improved the clinical setting of 83 % of highly selected patients treated, delaying the need for traditional surgical therapy.

Lumbar Spinal Stenosis Minimally Invasive Treatment with Bilateral Transpedicular Facet Augmentation System

International Nuclear Information System (INIS)

Masala, Salvatore; Tarantino, Umberto; Nano, Giovanni; Iundusi, Riccardo; Fiori, Roberto; Da Ros, Valerio; Simonetti, Giovanni

2013-01-01

Purpose. The purpose of this study was to evaluate the effectiveness of a new pedicle screw-based posterior dynamic stabilization device PDS Percudyn System™ Anchor and Stabilizer (Interventional Spine Inc., Irvine, CA) as alternative minimally invasive treatment for patients with lumbar spine stenosis. Methods. Twenty-four consecutive patients (8 women, 16 men; mean age 61.8 yr) with lumbar spinal stenosis underwent implantation of the minimally invasive pedicle screw-based device for posterior dynamic stabilization. Inclusion criteria were lumbar stenosis without signs of instability, resistant to conservative treatment, and eligible to traditional surgical posterior decompression. Results. Twenty patients (83 %) progressively improved during the 1-year follow-up. Four (17 %) patients did not show any improvement and opted for surgical posterior decompression. For both responder and nonresponder patients, no device-related complications were reported. Conclusions. Minimally invasive PDS Percudyn System™ has effectively improved the clinical setting of 83 % of highly selected patients treated, delaying the need for traditional surgical therapy.

Full Duplex Communications in 5G Small Cells

DEFF Research Database (Denmark)

Mahmood, Nurul Huda; Gatnau, Marta; Berardinelli, Gilberto

2017-01-01

Full duplex communication promises system performance improvement over conventional half duplex communication by allowing simultaneous transmission and reception. However, such concurrent communication results in strong self interference and an increase in the overall network interference, and can...... only be exploited when traffic is available in both directions. The potential throughput gains of full duplex communication over conventional half duplex transmission in a small cell network with asymmetric traffic conditions is investigated in this contribution. The throughput performance gains...... are analysed using tools from stochastic geometry, and further confirmed through extensive system level simulations. Our findings explicitly quantify how the gains from full duplex communication depend on the traffic profile and the inter-cell interference coupling. The demonstrated throughput gains and delay...

Early lexical development and risk of verbal and nonverbal cognitive delay at school age

NARCIS (Netherlands)

Ghassabian, A.; Rescorla, L.; Henrichs, J.; Jaddoe, V.W.; Verhulst, F.C.; Tiemeier, H.W.

2014-01-01

Aim To characterise the relationship between preschool lexical delay and language comprehension and nonverbal intelligence at school age. Methods The mothers of 2724 children completed the MacArthur Communicative Development Inventory when their child reached 1.5 years and the Language Development

Stability and delay sensitivity of neutral fractional-delay systems.

Science.gov (United States)

Xu, Qi; Shi, Min; Wang, Zaihua

2016-08-01

This paper generalizes the stability test method via integral estimation for integer-order neutral time-delay systems to neutral fractional-delay systems. The key step in stability test is the calculation of the number of unstable characteristic roots that is described by a definite integral over an interval from zero to a sufficient large upper limit. Algorithms for correctly estimating the upper limits of the integral are given in two concise ways, parameter dependent or independent. A special feature of the proposed method is that it judges the stability of fractional-delay systems simply by using rough integral estimation. Meanwhile, the paper shows that for some neutral fractional-delay systems, the stability is extremely sensitive to the change of time delays. Examples are given for demonstrating the proposed method as well as the delay sensitivity.

The minimal non-minimal standard model

International Nuclear Information System (INIS)

Bij, J.J. van der

2006-01-01

In this Letter I discuss a class of extensions of the standard model that have a minimal number of possible parameters, but can in principle explain dark matter and inflation. It is pointed out that the so-called new minimal standard model contains a large number of parameters that can be put to zero, without affecting the renormalizability of the model. With the extra restrictions one might call it the minimal (new) non-minimal standard model (MNMSM). A few hidden discrete variables are present. It is argued that the inflaton should be higher-dimensional. Experimental consequences for the LHC and the ILC are discussed

Ranking of delay factors in construction projects after Egyptian revolution

Directory of Open Access Journals (Sweden)

Remon Fayek Aziz

2013-09-01

Full Text Available Time is one of the major considerations throughout project management life cycle and can be regarded as one of the most important parameters of a project and the driving force of project success. Time delay is a very frequent phenomenon and is almost associated with nearly all constructing projects. However, little effort has been made to curtail the phenomenon, this research work attempts to identify, investigate, and rank factors perceived to affect delays in the Egyptian construction projects with respect to their relative importance so as to proffer possible ways of coping with this phenomenon. To achieve this objective, researcher invited practitioners and experts, comprising a statistically representative sample to participate in a structured questionnaire survey. Brain storming was taken into consideration, through which a number of delay factors were identified in construction projects. Totally, ninety-nine (99 factors were short-listed to be made part of the questionnaire survey and were identified and categorized into nine (9 major categories. The survey was conducted with experts and representatives from private, public, and local general construction firms. The data were analyzed using Relative Importance Index (RII, ranking and simple percentages. Ranking of factors and categories was demonstrated according to their importance level on delay, especially after 25/1/2011 (Egyptian revolution. According to the case study results, the most contributing factors and categories (those need attention to delays were discussed, and some recommendations were made in order to minimize and control delays in construction projects. Also, this paper can serve as a guide for all construction parties with effective management in construction projects to achieve a competitive level of quality and a time effective project.

Fundamentals of Delayed Coking Joint Industry Project

Energy Technology Data Exchange (ETDEWEB)

Michael Volk; Keith Wisecarver

2003-09-26

is 2,937,439 barrels/calendar day. These cokers produce 154,607 tons of coke per day and delayed coking accounts for 88% of the world capacity. The delayed coking charge capacity in the United States is 1,787,860 b/cd. Despite its wide commercial use, only relatively few contractors and refiners are truly knowledgeable in delayed-coking design, so that this process carries with it a ''black art'' connotation. Until recently, the expected yield from cokers was determined by a simple laboratory test on the feedstock. As a result of Tulsa University's prior related research, a process model was developed that with additional work could be used to optimize existing delayed cokers over a wide range of potential feedstocks and operating conditions. The objectives of this research program are to: utilize the current micro, batch and pilot unit facilities at The University of Tulsa to enhance the understanding of the coking process; conduct additional micro and pilot unit tests with new and in-house resids and recycles to make current optimization models more robust; conduct focused kinetic experiments to enhance the furnace tube model and to enhance liquid production while minimizing sulfur in the products; conduct detailed foaming studies to optimize the process and minimize process upsets; quantify the parameters that affect coke morphology; and to utilize the knowledge gained from the experimental and modeling studies to enhance the computer programs developed in the previous JIP for optimization of the coking process. These refined computer models will then be tested against refinery data provided by the member companies. Novel concepts will also be explored for hydrogen sulfide removal of furnace gases as well as gas injection studies to reduce over-cracking.

Method of synchronizing with an uplink channel and a method of determining a propagation delay in a wireless communications system

NARCIS (Netherlands)

Bosch, H.G.P.; Farag, E.N.; Mullender, Sape J.; Nathues, A.; Samuel, L.G.

2007-01-01

provided. In the example method of synchronizing, a propagation delay between a target base station and a mobile station is calculated. Then, the calculated propagation delay is sent to the target base station. In the example method of determining a propagation delay, a first signal is received

Impact of Degraded Communication on Interdependent Power Systems: The Application of Grid Splitting

Directory of Open Access Journals (Sweden)

Di-An Tian

2016-08-01

Full Text Available Communication is increasingly present for managing and controlling critical infrastructures strengthening their cyber interdependencies. In electric power systems, grid splitting is a topical communication-critical application. It amounts to separating a power system into islands in response to an impending instability, e.g., loss of generator synchronism due to a component fault, by appropriately disconnecting transmission lines and grouping synchronous generators. The successful application of grid splitting depends on the communication infrastructure to collect system-wide synchronized measurements and to relay the command to open line switches. Grid splitting may be ineffective if communication is degraded and its outcome may also depend on the system loading conditions. This paper investigates the effects of degraded communication and load variability on grid splitting. To this aim, a communication delay model is coupled with a transient electrical model and applied to the IEEE 39-Bus and the IEEE 118-Bus Test System. Case studies show that the loss of generator synchronism following a fault is mitigated by timely splitting the network into islands. On the other hand, the results show that communication delays and increased network flows can degrade the performance of grid splitting. The developed framework enables the identification of the requirements of the dedicated communication infrastructure for a successful grid-splitting procedure.

Area efficient decimation filter based on merged delay transformation for wireless applications

International Nuclear Information System (INIS)

Rashid, U.; Siddiq, F.; Muhammad, T.; Jamal, H.

2013-01-01

Expected by 2014 is the 4G standard for cellular wireless communications, which will improve bandwidth, connectivity and roaming for mobile and stationary devices, 4G and other wireless systems are currently hot topics of research and development in the communication field. In wireless technologies like Global System for Mobile (GSM), Digital Enhanced Cordless Telecommunications (DECT) and Wi-Fi, decimation filters are essential part of transceivers being used. This paper describes a decimation filter which is efficient in terms of both the power consumption and the area used. The architecture is based upon Merged Delay Transformation (MDT). The existing Merged Delay Transformed Infinite Impulse Response (IIR) architecture is power efficient but requires larger area. The proposed and existing filters were implemented on Field-Programmable Gate Array (FPGA). The computational cost of the proposed filter is reduced to (3N/2 + 1) and M-1 times reduction in the number of multipliers in comparison to the existing FIR filter is achieved. The power consumption and speed remain nearly the same. (author)

Minimalism

CERN Document Server

Obendorf, Hartmut

2009-01-01

The notion of Minimalism is proposed as a theoretical tool supporting a more differentiated understanding of reduction and thus forms a standpoint that allows definition of aspects of simplicity. This book traces the development of minimalism, defines the four types of minimalism in interaction design, and looks at how to apply it.

Use of Quadratic Time-Frequency Representations to Analyze Cetacean Mammal Sounds

National Research Council Canada - National Science Library

Papandreou-Suppappola, Antonia

2001-01-01

.... Analysis of the group delay structure of the mammalian vocal communication signals was matched to the appropriate quadratic time-frequency class for proper signal processing with minimal skewing of the results...

Variance-Constrained Robust Estimation for Discrete-Time Systems with Communication Constraints

Directory of Open Access Journals (Sweden)

Baofeng Wang

2014-01-01

Full Text Available This paper is concerned with a new filtering problem in networked control systems (NCSs subject to limited communication capacity, which includes measurement quantization, random transmission delay, and packets loss. The measurements are first quantized via a logarithmic quantizer and then transmitted through a digital communication network with random delay and packet loss. The three communication constraints phenomena which can be seen as a class of uncertainties are formulated by a stochastic parameter uncertainty system. The purpose of the paper is to design a linear filter such that, for all the communication constraints, the error state of the filtering process is mean square bounded and the steady-state variance of the estimation error for each state is not more than the individual prescribed upper bound. It is shown that the desired filtering can effectively be solved if there are positive definite solutions to a couple of algebraic Riccati-like inequalities or linear matrix inequalities. Finally, an illustrative numerical example is presented to demonstrate the effectiveness and flexibility of the proposed design approach.

Trends in mobile satellite communication

Science.gov (United States)

Johannsen, Klaus G.; Bowles, Mike W.; Milliken, Samuel; Cherrette, Alan R.; Busche, Gregory C.

1993-01-01

Ever since the U.S. Federal Communication Commission opened the discussion on spectrum usage for personal handheld communication, the community of satellite manufacturers has been searching for an economically viable and technically feasible satellite mobile communication system. Hughes Aircraft Company and others have joined in providing proposals for such systems, ranging from low to medium to geosynchronous orbits. These proposals make it clear that the trend in mobile satellite communication is toward more sophisticated satellites with a large number of spot beams and onboard processing, providing worldwide interconnectivity. Recent Hughes studies indicate that from a cost standpoint the geosynchronous satellite (GEOS) is most economical, followed by the medium earth orbit satellite (MEOS) and then by the low earth orbit satellite (LEOS). From a system performance standpoint, this evaluation may be in reverse order, depending on how the public will react to speech delay and collision. This paper discusses the trends and various mobile satellite constellations in satellite communication under investigation. It considers the effect of orbital altitude and modulation/multiple access on the link and spacecraft design.

Time Delay Estimation in Room Acoustic Environments: An Overview

Directory of Open Access Journals (Sweden)

Benesty Jacob

2006-01-01

Full Text Available Time delay estimation has been a research topic of significant practical importance in many fields (radar, sonar, seismology, geophysics, ultrasonics, hands-free communications, etc.. It is a first stage that feeds into subsequent processing blocks for identifying, localizing, and tracking radiating sources. This area has made remarkable advances in the past few decades, and is continuing to progress, with an aim to create processors that are tolerant to both noise and reverberation. This paper presents a systematic overview of the state-of-the-art of time-delay-estimation algorithms ranging from the simple cross-correlation method to the advanced blind channel identification based techniques. We discuss the pros and cons of each individual algorithm, and outline their inherent relationships. We also provide experimental results to illustrate their performance differences in room acoustic environments where reverberation and noise are commonly encountered.

Control and estimation methods over communication networks

CERN Document Server

Mahmoud, Magdi S

2014-01-01

This book provides a rigorous framework in which to study problems in the analysis, stability and design of networked control systems. Four dominant sources of difficulty are considered: packet dropouts, communication bandwidth constraints, parametric uncertainty, and time delays. Past methods and results are reviewed from a contemporary perspective, present trends are examined, and future possibilities proposed. Emphasis is placed on robust and reliable design methods. New control strategies for improving the efficiency of sensor data processing and reducing associated time delay are presented. The coverage provided features: ·        an overall assessment of recent and current fault-tolerant control algorithms; ·        treatment of several issues arising at the junction of control and communications; ·        key concepts followed by their proofs and efficient computational methods for their implementation; and ·        simulation examples (including TrueTime simulations) to...

Tunable Optical True-Time Delay Devices Would Exploit EIT

Science.gov (United States)

Kulikov, Igor; DiDomenico, Leo; Lee, Hwang

2004-01-01

Tunable optical true-time delay devices that would exploit electromagnetically induced transparency (EIT) have been proposed. Relative to prior true-time delay devices (for example, devices based on ferroelectric and ferromagnetic materials) and electronically controlled phase shifters, the proposed devices would offer much greater bandwidths. In a typical envisioned application, an optical pulse would be modulated with an ultra-wideband radio-frequency (RF) signal that would convey the information that one seeks to communicate, and it would be required to couple differently delayed replicas of the RF signal to the radiating elements of a phased-array antenna. One or more of the proposed devices would be used to impose the delays and/or generate the delayed replicas of the RF-modulated optical pulse. The beam radiated or received by the antenna would be steered by use of a microprocessor-based control system that would adjust operational parameters of the devices to tune the delays to the required values. EIT is a nonlinear quantum optical interference effect that enables the propagation of light through an initially opaque medium. A suitable medium must have, among other properties, three quantum states (see Figure 1): an excited state (state 3), an upper ground state (state 2), and a lower ground state (state 1). These three states must form a closed system that exhibits no decays to other states in the presence of either or both of two laser beams: (1) a probe beam having the wavelength corresponding to the photon energy equal to the energy difference between states 3 and 1; and (2) a coupling beam having the wavelength corresponding to the photon energy equal to the energy difference between states 3 and 2. The probe beam is the one that is pulsed and modulated with an RF signal.

Exploiting geo-distributed clouds for a e-health monitoring system with minimum service delay and privacy preservation.

Science.gov (United States)

Shen, Qinghua; Liang, Xiaohui; Shen, Xuemin; Lin, Xiaodong; Luo, Henry Y

2014-03-01

In this paper, we propose an e-health monitoring system with minimum service delay and privacy preservation by exploiting geo-distributed clouds. In the system, the resource allocation scheme enables the distributed cloud servers to cooperatively assign the servers to the requested users under the load balance condition. Thus, the service delay for users is minimized. In addition, a traffic-shaping algorithm is proposed. The traffic-shaping algorithm converts the user health data traffic to the nonhealth data traffic such that the capability of traffic analysis attacks is largely reduced. Through the numerical analysis, we show the efficiency of the proposed traffic-shaping algorithm in terms of service delay and privacy preservation. Furthermore, through the simulations, we demonstrate that the proposed resource allocation scheme significantly reduces the service delay compared to two other alternatives using jointly the short queue and distributed control law.

Experimental Evaluation of Novel Master-Slave Configurations for Position Control under Random Network Delay and Variable Load for Teleoperation

Directory of Open Access Journals (Sweden)

Ahmet Kuzu

2014-01-01

Full Text Available This paper proposes two novel master-slave configurations that provide improvements in both control and communication aspects of teleoperation systems to achieve an overall improved performance in position control. The proposed novel master-slave configurations integrate modular control and communication approaches, consisting of a delay regulator to address problems related to variable network delay common to such systems, and a model tracking control that runs on the slave side for the compensation of uncertainties and model mismatch on the slave side. One of the configurations uses a sliding mode observer and the other one uses a modified Smith predictor scheme on the master side to ensure position transparency between the master and slave, while reference tracking of the slave is ensured by a proportional-differentiator type controller in both configurations. Experiments conducted for the networked position control of a single-link arm under system uncertainties and randomly varying network delays demonstrate significant performance improvements with both configurations over the past literature.

Earth system commitments due to delayed mitigation

International Nuclear Information System (INIS)

Pfister, Patrik L; Stocker, Thomas F

2016-01-01

As long as global CO 2 emissions continue to increase annually, long-term committed Earth system changes grow much faster than current observations. A novel metric linking this future growth to policy decisions today is the mitigation delay sensitivity (MDS), but MDS estimates for Earth system variables other than peak temperature (ΔT max ) are missing. Using an Earth System Model of Intermediate Complexity, we show that the current emission increase rate causes a ΔT max increase roughly 3–7.5 times as fast as observed warming, and a millenial steric sea level rise (SSLR) 7–25 times as fast as observed SSLR, depending on the achievable rate of emission reductions after the peak of emissions. These ranges are only slightly affected by the uncertainty range in equilibrium climate sensitivity, which is included in the above values. The extent of ocean acidification at the end of the century is also strongly dependent on the starting time and rate of emission reductions. The preservable surface ocean area with sufficient aragonite supersaturation for coral reef growth is diminished globally at an MDS of roughly 25%–80% per decade. A near-complete loss of this area becomes unavoidable if mitigation is delayed for a few years to decades. Also with respect to aragonite, 12%–18% of the Southern Ocean surface become undersaturated per decade, if emission reductions are delayed beyond 2015–2040. We conclude that the consequences of delaying global emission reductions are much better captured if the MDS of relevant Earth system variables is communicated in addition to current trends and total projected future changes. (letter)

Spectrum optimization-based chaotification using time-delay feedback control

International Nuclear Information System (INIS)

Zhou Jiaxi; Xu Daolin; Zhang Jing; Liu Chunrong

2012-01-01

Highlights: ► A time-delay feedback controller is designed for chaotification. ► A spectrum optimization method is proposed to determine chaotification parameters. ► Numerical examples verify the spectrum optimization- based chaotification method. ► Engineering application in line spectrum reconfiguration is demonstrated. - Abstract: In this paper, a spectrum optimization method is developed for chaotification in conjunction with an application in line spectrum reconfiguration. A key performance index (the objective function) based on Fourier spectrum is specially devised with the idea of suppressing spectrum spikes and broadening frequency band. Minimization of the index empowered by a genetic algorithm enables to locate favorable parameters of the time-delay feedback controller, by which a line spectrum of harmonic vibration can be transformed into a broad-band continuous spectrum of chaotic motion. Numerical simulations are carried out to verify the feasibility of the method and to demonstrate its effectiveness of chaotifying a 2-DOFs linear mechanical system.

Sunscreens for delay of ultraviolet induction of skin tumors

International Nuclear Information System (INIS)

Wulf, H.C.; Poulsen, T.; Brodthagen, H.; Hou-Jensen, K.

1982-01-01

Sunscreens with different sun protection factors (SPFs) have been tested for their capability of delaying or preventing actinic damage and skin cancer development in groups of hairless, pigmented mice exposed to artificial ultraviolet (UV) light of increasing intensity. The dose delivered was less than or equal to 1 minimal erythema dose (MED) in the group of untreated mice, so that the mice to which sunscreens were applied never obtained a sunburn after UV exposure. The quality of UV light was similar to bright midday sun at a latitude of 56 degrees (city of Copenhagen). Tumorigenesis was demonstrated to be delayed corresponding to the SPF claimed by the manufacturer, but almost all of the UV-irradiated mice developed skin tumors. Histologic examination revealed actinic degeneration and tumors of squamous cell type with marked variation in differentiation. Metastases to lymph nodes and lungs were found in only 10%. Toxic reactions, such as eczematous-like skin reactions, dark coloring, and amyloidosis, were observed predominantly in the group treated with the sunscreen of highest SPF value. Long-term investigations seem to be necessary to unveil these problems--in particular, the specific SPF value, in sunscreens, that should be recommended to the public for prevention or delay of actinic damage and/or cancer development

A 3-Factor Model Relating Communication to Risk Mitigation of Extended Information System Failover

Directory of Open Access Journals (Sweden)

Athanasios Podaras

2015-06-01

Full Text Available This paper aims to analyse the relation between timely and effective communication and risk mitigation of late recovery after an unexpected information system outage in enterprises. An unforeseen information system failure in modern enterprise units, may result to significant operational and financial damage. In such a critical incident, effective communication between the team leaders and the recovery team involved, can minimize or even eliminate this negative impact. An extended information system outage can be perceived as a time deviation from the Maximum Accepted Outage (ΜΑΟ timeframe, proposed by the business continuity management, according to the value of which dependent business functions may be interrupted without any serious effects to the company. The paper examines the relation between 3 basic factors and the efficient communication between team members. The factors are: timely information distribution, staff availability and network availability. Through the current paper, the author proposes a risk analysis model, based on the Composite Risk Index theory of Risk Management, which can significantly diminish the possibility of an extended information system outage, as well as calculate the extended time required to recover a system when the aforementioned factors emerge in their worst form. The precise calculation of recovery time can be achieved via the execution of business continuity tests which include scenarios, according to which an unexpected system outage coexists with delayed information distribution as well as low staff and network availability.

The Use of Video Modeling with the Picture Exchange Communication System to Increase Independent Communicative Initiations in Preschoolers with Autism and Developmental Delays

Science.gov (United States)

Cihak, David F.; Smith, Catherine C.; Cornett, Ashlee; Coleman, Mari Beth

2012-01-01

The use of video modeling (VM) procedures in conjunction with the picture exchange communication system (PECS) to increase independent communicative initiations in preschool-age students was evaluated in this study. The four participants were 3-year-old children with limited communication skills prior to the intervention. Two of the students had…

Comparing the Picture Exchange Communication System and the iPad™ for Communication of Students with Autism Spectrum Disorder and Developmental Delay

Science.gov (United States)

Hill, Doris Adams; Flores, Margaret M.

2014-01-01

Both picture exchange, a low-tech picturebased communication system, and technologybased interventions, such as the iPad™ with communication application, are emerging treatments for students with autism spectrum disorder (ASD), according to the National Autism Center (2009). Recently, investigations regarding the use of the Apple iPad™ to…

Estimating Angle of Arrival (AOA for Wideband Signal by Sensor Delay Line (SDL and Tapped Delay Line (TDL Processors

Directory of Open Access Journals (Sweden)

Bassim Sayed Mohammed

2018-04-01

Full Text Available Angle of arrival (AOA estimation for wideband signal becomes more necessary for modern communication systems like Global System for Mobile (GSM, satellite, military applications and spread spectrum (frequency hopping and direct sequence. Most of the researchers are focusing on how to cancel the effects of signal bandwidth on AOA estimation performance by using a transversal filter (tap delay line (TDL. Most of the researchers were using two elements array antenna to study these effects. In this research, a general case of proposed (M array elements is used. A transversal filter (TDL in phase adaptive array antenna system is used to calculate the optimum number of taps required to compensate these effect. The proposed system uses a phase adaptive array antenna in conjunction with LMS algorithm to work an angle of arrival (AOA estimator for wideband signals rather than interference canceller. An alternative solution to compensate for the effect of signal bandwidth is proposed by using sensor delay line (SDL instead of fixed delay unit since it has variable time sampling in the time domain and not fixed time delay, depending on the angle of arrival of received signals. The proposed system has the ability to estimate two parameters for received signals simultaneously (the output Signal to Noise Ratio (SNR and AOA, unlike others systems which estimate AOA only. The comparison of the simulation results with Multiple Signal Classification (MUSIC technique showed that the proposed system gives good results for estimating AOA and the output SNR for wideband signals. (SDL processor shows better performance result than (TDL processor. MUSIC technique with both (SDL and (TDL processors shows unacceptable results for estimating (AOA for the wideband signal.

Minimal changes in health status questionnaires: distinction between minimally detectable change and minimally important change

Directory of Open Access Journals (Sweden)

Knol Dirk L

2006-08-01

Full Text Available Abstract Changes in scores on health status questionnaires are difficult to interpret. Several methods to determine minimally important changes (MICs have been proposed which can broadly be divided in distribution-based and anchor-based methods. Comparisons of these methods have led to insight into essential differences between these approaches. Some authors have tried to come to a uniform measure for the MIC, such as 0.5 standard deviation and the value of one standard error of measurement (SEM. Others have emphasized the diversity of MIC values, depending on the type of anchor, the definition of minimal importance on the anchor, and characteristics of the disease under study. A closer look makes clear that some distribution-based methods have been merely focused on minimally detectable changes. For assessing minimally important changes, anchor-based methods are preferred, as they include a definition of what is minimally important. Acknowledging the distinction between minimally detectable and minimally important changes is useful, not only to avoid confusion among MIC methods, but also to gain information on two important benchmarks on the scale of a health status measurement instrument. Appreciating the distinction, it becomes possible to judge whether the minimally detectable change of a measurement instrument is sufficiently small to detect minimally important changes.

An Evaluation of Strategies for Training Staff to Implement the Picture Exchange Communication System

Science.gov (United States)

Barnes, Clarissa S.; Dunning, Johnna L.; Rehfeldt, Ruth Anne

2011-01-01

The picture exchange communication system (PECS) is a functional communication system frequently used with individuals diagnosed with autism spectrum disorders who experience severe language delays (Frost & Bondy, 2002). Few empirical investigations have evaluated strategies for training direct care staff how to effectively implement PECS with…

Stochastic resonance in a bistable system subject to multi-time-delayed feedback and aperiodic signal

International Nuclear Information System (INIS)

Li Jianlong; Zeng Lingzao

2010-01-01

We discuss in detail the effects of the multi-time-delayed feedback driven by an aperiodic signal on the output of a stochastic resonance (SR) system. The effective potential function and dynamical probability density function (PDF) are derived. To measure the performance of the SR system in the presence of a binary random signal, the bit error rate (BER) defined by the dynamical PDF is employed, as is commonly used in digital communications. We find that the delay time, strength of the feedback, and number of time-delayed terms can change the effective potential function and the effective amplitude of the signal, and then affect the BER of the SR system. The numerical simulations strongly support the theoretical results. The goal of this investigation is to explore the effects of the multi-time-delayed feedback on SR and give a guidance to nonlinear systems in the application of information processing.

Fuzzy delay model based fault simulator for crosstalk delay fault test ...

Indian Academy of Sciences (India)

In this paper, a fuzzy delay model based crosstalk delay fault simulator is proposed. As design trends move towards nanometer technologies, more number of new parameters affects the delay of the component. Fuzzy delay models are ideal for modelling the uncertainty found in the design and manufacturing steps.

A Compact, Low Power Pulsed Optical Communication System for Spacecraft

Data.gov (United States)

National Aeronautics and Space Administration — The goal of this project is to reduce the power required for high bandwidth, deep space laser communications systems. Our concept will encode data in the time delay...

Coexistence of enhanced mobile broadband communications and ultra-reliable low-latency communications in mobile front-haul

Science.gov (United States)

Ying, Kai; Kowalski, John M.; Nogami, Toshizo; Yin, Zhanping; Sheng, Jia

2018-01-01

5G systems are supposed to support coexistence of multiple services such as ultra reliable low latency communications (URLLC) and enhanced mobile broadband (eMBB) communications. The target of eMBB communications is to meet the high-throughput requirement while URLLC are used for some high priority services. Due to the sporadic nature and low latency requirement, URLLC transmission may pre-empt the resource of eMBB transmission. Our work is to analyze the URLLC impact on eMBB transmission in mobile front-haul. Then, some solutions are proposed to guarantee the reliability/latency requirements for URLLC services and minimize the impact to eMBB services at the same time.

[Management of spinal metastasis by minimal invasive surgery technique: Surgical principles, indications: A literature review].

Science.gov (United States)

Toquart, A; Graillon, T; Mansouri, N; Adetchessi, T; Blondel, B; Fuentes, S

2016-06-01

Spinal metastasis are getting more frequent. This raises the question of pain and neurological complications, which worsen the functional and survival prognosis of this oncological population patients. The surgical treatment must be the most complete as possible: to decompress and stabilize without delaying the management of the oncological disease. Minimal invasive surgery techniques are by definition, less harmful on musculocutaneous plan than opened ones, with a comparable efficiency demonstrated in degenerative and traumatic surgery. So they seem to be applicable and appropriate to this patient population. We detailed different minimal invasive techniques proposed in the management of spinal metastasis. For this, we used our experience developed in degenerative and traumatic pathologies, and we also referred to many authors, establishing a literature review thanks to Pubmed, Embase. Thirty eight articles were selected and allowed us to describe different techniques: percutaneous methods such as vertebro-/kyphoplasty and osteosynthesis, as well as mini-opened surgery, through a posterior or anterior way. We propose a surgical approach using these minimal invasive techniques, first according to the predominant symptom (pain or neurologic failure), then characteristics of the lesions (number, topography, type…) and the deformity degree. Whatever the technique, the main goal is to stabilize and decompress, in order to maintain a good quality of life for these fragile patients, without delaying the medical management of the oncological disease. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Analysis of subpulse generation from delayed-interference signal-wavelength converter for wide carrier recovery rate range

DEFF Research Database (Denmark)

Sakaguchi, J.; Nielsen, Mads Lønstrup; Ohira, T.

2008-01-01

The generation of subpulses in delayed-interference signal-wavelength converters (DISCS) had been suspected as a Curse of waveform degradation in their application in ultrafast (similar to 160GHz) optical time division multiplexing (OTDM) communication systems. We reported its first observation...

Delay Reduction for Instantly Decodable Network Coding in Persistent Channels With Feedback Imperfections

KAUST Repository

Douik, Ahmed S.

2015-11-05

This paper considers the multicast decoding delay reduction problem for generalized instantly decodable network coding (G-IDNC) over persistent erasure channels with feedback imperfections. The feedback scenario discussed is the most general situation in which the sender does not always receive acknowledgments from the receivers after each transmission and the feedback communications are subject to loss. The decoding delay increment expressions are derived and employed to express the decoding delay reduction problem as a maximum weight clique problem in the G-IDNC graph. This paper provides a theoretical analysis of the expected decoding delay increase at each time instant. Problem formulations in simpler channel and feedback models are shown to be special cases of the proposed generalized formulation. Since finding the optimal solution to the problem is known to be NP-hard, a suboptimal greedy algorithm is designed and compared with blind approaches proposed in the literature. Through extensive simulations, the proposed algorithm is shown to outperform the blind methods in all situations and to achieve significant improvement, particularly for high time-correlated channels.

Delay Reduction for Instantly Decodable Network Coding in Persistent Channels With Feedback Imperfections

KAUST Repository

Douik, Ahmed S.; Sorour, Sameh; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

2015-01-01

This paper considers the multicast decoding delay reduction problem for generalized instantly decodable network coding (G-IDNC) over persistent erasure channels with feedback imperfections. The feedback scenario discussed is the most general situation in which the sender does not always receive acknowledgments from the receivers after each transmission and the feedback communications are subject to loss. The decoding delay increment expressions are derived and employed to express the decoding delay reduction problem as a maximum weight clique problem in the G-IDNC graph. This paper provides a theoretical analysis of the expected decoding delay increase at each time instant. Problem formulations in simpler channel and feedback models are shown to be special cases of the proposed generalized formulation. Since finding the optimal solution to the problem is known to be NP-hard, a suboptimal greedy algorithm is designed and compared with blind approaches proposed in the literature. Through extensive simulations, the proposed algorithm is shown to outperform the blind methods in all situations and to achieve significant improvement, particularly for high time-correlated channels.

Stoma creation: does onset of ostomy care education delay hospital length of stay?

Science.gov (United States)

Rashidi, Laila; Long, Kevin; Hawkins, Melinda; Menon, Raman; Bellevue, Oliver

2016-05-01

Balancing patient safety with hospital length of stay (LOS) and associated cost is critically important. Subjectively, we have observed that patients undergoing ostomy creation early in the week have a shorter LOS. We retrospectively reviewed LOS based on day of the week the operation was performed. We reviewed 180 patients undergoing minimally invasive surgery with planned ostomy. Group 1 underwent surgery on Monday to Wednesday (n = 77), Group 2 on Thursday (n = 49), and Group 3 on Friday (n = 54). The average LOS for Group 1, 2, and 3 was 6.2, 4.9, and 7.2 days, respectively. The average number of visits with ostomy nursing for Group 1, 2, and 3 was 2.7, 1.8, and 2.3, respectively. Day of initial ostomy nursing visit was significantly correlated between the delay to initial visit and LOS with Group 3 delayed most. Patients with the longest delay to initial nurse visit had the longest LOS, with Friday operations being most delayed. A contributing factor may be absence of ostomy teaching over the weekend. Copyright © 2016 Elsevier Inc. All rights reserved.

Parenting Practices and Associations with Development Delays among Young Children in Dominican Republic.

Science.gov (United States)

Uwemedimo, Omolara Thomas; Howlader, Afrin; Pierret, Giselina

According to the World Health Organization, >200 million children in low- and middle-income countries experience developmental delays. However, household structure and parenting practices have been minimally explored as potential correlates of developmental delay in low- and middle-income countries, despite potential as areas for intervention. The objective of the study was to examine associations of developmental delays with use of World Health Organization-recommended parenting practices among a clinic-based cohort of children aged 6-60 months attending in La Romana, Dominican Republic. This study was conducted among 74 caregiver-child pairs attending the growth-monitoring clinic at Hospital Francisco Gonzalvo in June 2015. The Malawi Developmental Assessment Tool was adapted and performed on each child to assess socioadaptive, fine motor, gross motor, and language development. The IMCI Household Level Survey Questionnaire was used to assess parenting practices. Fisher's exact test was used to determine associations significant at P children had a delay in at least 1 developmental domain. Most caregivers used scolding (43.2%) or spanking (44%) for child discipline. Children who were disciplined by spanking and scolding were more likely to have language delay (P = .007) and socioadaptive delay (P = .077), respectively. On regression analysis, children with younger primary caregivers had 7 times higher odds of language delay (adjusted odds ratio [AOR]: 7.35, 95% confidence interval [CI]: 1.52-35.61) and 4 times greater odds of any delay (AOR: 4.72, 95% CI: 1.01-22.22). In addition, children punished by spanking had 5 times higher odds of having language delay (AOR: 5.04, 95% CI: 1.13-22.39). Parenting practices such as harsh punishment and lack of positive parental reinforcement were found to have strong associations with language and socioadaptive delays. Likewise, delays were also more common among children with younger caregivers. Copyright © 2017 Icahn

On the cost/delay tradeoff of wireless delay tolerant geographic routing

OpenAIRE

Tasiopoulos, Argyrios; Tsiaras, Christos; Toumpis, Stavros

2012-01-01

In Delay Tolerant Networks (DTNs), there is a fundamental tradeoff between the aggregate transport cost of a packet and the delay in its delivery. We study this tradeoff in the context of geographical routing in wireless DTNs.We ?rst specify the optimal cost/delay tradeoff, i.e., the tradeoff under optimal network operation, using a dynamic network construction termed the Cost/Delay Evolving Graph (C/DEG) and the Optimal Cost/Delay Curve (OC/DC), a function that gives the minimum possible agg...

Leveraging delay discounting for health: Can time delays influence food choice?

Science.gov (United States)

Appelhans, Bradley M; French, Simone A; Olinger, Tamara; Bogucki, Michael; Janssen, Imke; Avery-Mamer, Elizabeth F; Powell, Lisa M

2018-03-15

Delay discounting, the tendency to choose smaller immediate rewards over larger delayed rewards, is theorized to promote consumption of immediately rewarding but unhealthy foods at the expense of long-term weight maintenance and nutritional health. An untested implication of delay discounting models of decision-making is that selectively delaying access to less healthy foods may promote selection of healthier (immediately available) alternatives, even if they may be less desirable. The current study tested this hypothesis by measuring healthy versus regular vending machine snack purchasing before and during the implementation of a 25-s time delay on the delivery of regular snacks. Purchasing was also examined under a $0.25 discount on healthy snacks, a $0.25 tax on regular snacks, and the combination of both pricing interventions with the 25-s time delay. Across 32,019 vending sales from three separate vending locations, the 25-s time delay increased healthy snack purchasing from 40.1% to 42.5%, which was comparable to the impact of a $0.25 discount (43.0%). Combining the delay and the discount had a roughly additive effect (46.0%). However, the strongest effects were seen under the $0.25 tax on regular snacks (53.7%) and the combination of the delay and the tax (50.2%). Intervention effects varied substantially between vending locations. Importantly, time delays did not harm overall vending sales or revenue, which is relevant to the real-world feasibility of this intervention. More investigation is needed to better understand how the impact of time delays on food choice varies across populations, evaluate the effects of time delays on beverage vending choices, and extend this approach to food choices in contexts other than vending machines. ClinicalTrials.gov, NCT02359916. Copyright © 2018 Elsevier Ltd. All rights reserved.

Associations between parents' satisfaction with provider communication and HPV vaccination behaviors.

Science.gov (United States)

Kornides, Melanie L; Fontenot, Holly B; McRee, Annie-Laurie; Panozzo, Catherine A; Gilkey, Melissa B

2018-05-03

Despite increasing awareness of the importance of a provider recommendation for HPV vaccine, the U.S. has yet to achieve the Healthy people 2020 goal of 80% series completion among adolescents. This failure indicates a need for further examination of the modifiable influences on parents' decision-making. Healthcare providers can influence parents' HPV vaccination decision-making, but little is known about parents' perspectives on the counseling they receive. We sought to assess U.S. parents' satisfaction with provider communication about HPV vaccine and associations with vaccination behaviors. Parents of 11-to-17-year-old adolescents who discussed HPV vaccination with a healthcare provider at least once (n = 795) completed our online survey in Fall 2016. We assessed their satisfaction with the discussion using the HPV Vaccine Communication Satisfaction Scale (α = 0.94). We examined associations between satisfaction (categorized as low, moderate, or high), and three vaccination behaviors: refusal/delay, series initiation (≥1 dose), and continuation (≥2 doses among initiators) using multivariable logistic regression. Most parents reported high (36%) or moderate (38%) satisfaction with provider communication about HPV vaccination; fewer reported low (26%) satisfaction. Moderately satisfied parents (vs. low) had lower odds of refusal/delay (aOR = 0.59, 95% CI: 0.38-0.89), and higher odds of initiation (aOR = 1.71, 95% CI:1.15-2.55) and continuation (aOR = 2.05, 95% CI: 1.24-3.40). The associations were stronger for highly satisfied parents (refusal/delay aOR = 0.45, 95% CI: 0.29-0.70, initiation aOR = 3.59, 95% CI: 2.23-5.78, and continuation aOR = 4.08, 95% CI: 2.38-7.01). Our study suggests that parent satisfaction with provider communication may play an important role in HPV vaccination decision-making. Yet, communication satisfaction has been largely unexamined in the HPV-vaccine literature to date. We introduce a brief, 7-item

Minimal surfaces

CERN Document Server

Dierkes, Ulrich; Sauvigny, Friedrich; Jakob, Ruben; Kuster, Albrecht

2010-01-01

Minimal Surfaces is the first volume of a three volume treatise on minimal surfaces (Grundlehren Nr. 339-341). Each volume can be read and studied independently of the others. The central theme is boundary value problems for minimal surfaces. The treatise is a substantially revised and extended version of the monograph Minimal Surfaces I, II (Grundlehren Nr. 295 & 296). The first volume begins with an exposition of basic ideas of the theory of surfaces in three-dimensional Euclidean space, followed by an introduction of minimal surfaces as stationary points of area, or equivalently

Communication and Wiring in the Cortical Connectome

Directory of Open Access Journals (Sweden)

Julian eBudd

2012-10-01

Full Text Available In cerebral cortex, the huge mass of axonal wiring that carries information between near and distant neurons is thought to provide the neural substrate for cognitive and perceptual function. The goal of mapping the connectivity of cortical axons at different spatial scales, the cortical connectome, is to trace the paths of information flow in cerebral cortex. To appreciate the relationship between the connectome and cortical function, we need to discover the nature and purpose of the wiring principles underlying cortical connectivity. A popular explanation has been that axonal length is strictly minimized both within and between cortical regions. In contrast, we have hypothesized the existence of a multi-scale principle of cortical wiring where to optimise communication there is a trade-off between spatial (construction and temporal (routing costs. Here, using recent evidence concerning cortical spatial networks we critically evaluate this hypothesis at neuron, local circuit, and pathway scales. We report three main conclusions. First, the axonal and dendritic arbor morphology of single neocortical neurons may be governed by a similar wiring principle, one that balances the conservation of cellular material and conduction delay. Second, the same principle may be observed for fibre tracts connecting cortical regions. Third, the absence of sufficient local circuit data currently prohibits any meaningful assessment of the hypothesis at this scale of cortical organization. To avoid neglecting neuron and microcircuit levels of cortical organization, the connectome framework should incorporate more morphological description. In addition, structural analyses of temporal cost for cortical circuits should take account of both axonal conduction and neuronal integration delays, which appear mostly of the same order of magnitude. We conclude the hypothesized trade-off between spatial and temporal costs may potentially offer a powerful explanation for

Maternal Sensitivity and Communication Styles: Mothers with Depression

Science.gov (United States)

Hwa-Froelich, Deborah A.; Loveland Cook, Cynthia A.; Flick, Louise H.

2008-01-01

Women living in poverty are at increased risk for depression, especially during their childbearing years. Whereas poverty has known adverse effects on children's cognitive, social, and communication development, maternal depression may place these children at additional risk of developmental delays. The maternal sensitivity of mothers with and…

[Communicating research with social media].

Science.gov (United States)

Bennato, Davide

2014-09-01

Participation is the new keyword of communication. In the scientific field, communication is a very complex task that can't ignore the careful consideration of the target audience. To minimize the difficulties, it is useful to rely on storytelling: it can greatly benefit from the space offered by social media that can be used to raise awareness and to engage through the sharing of experiences. The marriage between scientific research and social media can take place, as long as you carefully reflect on the roles, strategies and appropriate tools.

Infrared Free Space Communication - The Autonomous Testing of Free Space Infrared Communication

Science.gov (United States)

Heldman, Christopher

2017-01-01

Fiber optics has been a winning player in the game of high-speed communication and data transfer in cable connections. Yet, in free space RF has been the repeated choice of communication medium of the space industry. Investigating the benefits of free space optical communication over radio frequency is worthwhile. An increase in science data rate return capabilities could occur if optical communication is implemented. Optical communication systems also provide efficiencies in power, mass, and volume over RF systems1. Optical communication systems have been demonstrated from a satellite in orbit with the moon to earth, and resulted in the highest data rates ever seen through space (622Mbps)2. Because of these benefits, optical communication is far superior to RF. The HiDRA (High Data Rate Architecture) project is researching Passive Misalignment Mitigation of Dynamic Free Apace Optical Communication Links. The goal of this effort is to enable gigabit per second transmission of data in short range dynamic links (less than 100 meters). In practice this would enhance data rates between sites on the International Space Station with minimal size, weight, and power requirements. This paper will focus on an autonomous code and a hardware setup that will be used to fulfill the next step in the research being conducted. The free space optical communications pointing downfalls will be investigated. This was achieved by creating 5 python programs and a top-level code to automate this test.

Delay reduction in persistent erasure channels for generalized instantly decodable network coding

KAUST Repository

Sorour, Sameh

2013-06-01

In this paper, we consider the problem of minimizing the decoding delay of generalized instantly decodable network coding (G-IDNC) in persistent erasure channels (PECs). By persistent erasure channels, we mean erasure channels with memory, which are modeled as a Gilbert-Elliott two-state Markov model with good and bad channel states. In this scenario, the channel erasure dependence, represented by the transition probabilities of this channel model, is an important factor that could be exploited to reduce the decoding delay. We first formulate the G-IDNC minimum decoding delay problem in PECs as a maximum weight clique problem over the G-IDNC graph. Since finding the optimal solution of this formulation is NP-hard, we propose two heuristic algorithms to solve it and compare them using extensive simulations. Simulation results show that each of these heuristics outperforms the other in certain ranges of channel memory levels. They also show that the proposed heuristics significantly outperform both the optimal strict IDNC in the literature and the channel-unaware G-IDNC algorithms. © 2013 IEEE.

Delay reduction in persistent erasure channels for generalized instantly decodable network coding

KAUST Repository

Sorour, Sameh; Aboutorab, Neda; Sadeghi, Parastoo; Karim, Mohammad Shahriar; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

2013-01-01

In this paper, we consider the problem of minimizing the decoding delay of generalized instantly decodable network coding (G-IDNC) in persistent erasure channels (PECs). By persistent erasure channels, we mean erasure channels with memory, which are modeled as a Gilbert-Elliott two-state Markov model with good and bad channel states. In this scenario, the channel erasure dependence, represented by the transition probabilities of this channel model, is an important factor that could be exploited to reduce the decoding delay. We first formulate the G-IDNC minimum decoding delay problem in PECs as a maximum weight clique problem over the G-IDNC graph. Since finding the optimal solution of this formulation is NP-hard, we propose two heuristic algorithms to solve it and compare them using extensive simulations. Simulation results show that each of these heuristics outperforms the other in certain ranges of channel memory levels. They also show that the proposed heuristics significantly outperform both the optimal strict IDNC in the literature and the channel-unaware G-IDNC algorithms. © 2013 IEEE.

Cyclopentane combustion. Part II. Ignition delay measurements and mechanism validation

KAUST Repository

Rachidi, Mariam El

2017-06-12

This study reports cyclopentane ignition delay measurements over a wide range of conditions. The measurements were obtained using two shock tubes and a rapid compression machine, and were used to test a detailed low- and high-temperature mechanism of cyclopentane oxidation that was presented in part I of this study (Al Rashidi et al., 2017). The ignition delay times of cyclopentane/air mixtures were measured over the temperature range of 650–1350K at pressures of 20 and 40atm and equivalence ratios of 0.5, 1.0 and 2.0. The ignition delay times simulated using the detailed chemical kinetic model of cyclopentane oxidation show very good agreement with the experimental measurements, as well as with the cyclopentane ignition and flame speed data available in the literature. The agreement is significantly improved compared to previous models developed and investigated at higher temperatures. Reaction path and sensitivity analyses were performed to provide insights into the ignition-controlling chemistry at low, intermediate and high temperatures. The results obtained in this study confirm that cycloalkanes are less reactive than their non-cyclic counterparts. Moreover, cyclopentane, a high octane number and high octane sensitivity fuel, exhibits minimal low-temperature chemistry and is considerably less reactive than cyclohexane. This study presents the first experimental low-temperature ignition delay data of cyclopentane, a potential fuel-blending component of particular interest due to its desirable antiknock characteristics.

Cyclopentane combustion. Part II. Ignition delay measurements and mechanism validation

KAUST Repository

Rachidi, Mariam El; Má rmol, Juan C.; Banyon, Colin; Sajid, Muhammad Bilal; Mehl, Marco; Pitz, William J.; Mohamed, Samah; Alfazazi, Adamu; Lu, Tianfeng; Curran, Henry J.; Farooq, Aamir; Sarathy, Mani

2017-01-01

This study reports cyclopentane ignition delay measurements over a wide range of conditions. The measurements were obtained using two shock tubes and a rapid compression machine, and were used to test a detailed low- and high-temperature mechanism of cyclopentane oxidation that was presented in part I of this study (Al Rashidi et al., 2017). The ignition delay times of cyclopentane/air mixtures were measured over the temperature range of 650–1350K at pressures of 20 and 40atm and equivalence ratios of 0.5, 1.0 and 2.0. The ignition delay times simulated using the detailed chemical kinetic model of cyclopentane oxidation show very good agreement with the experimental measurements, as well as with the cyclopentane ignition and flame speed data available in the literature. The agreement is significantly improved compared to previous models developed and investigated at higher temperatures. Reaction path and sensitivity analyses were performed to provide insights into the ignition-controlling chemistry at low, intermediate and high temperatures. The results obtained in this study confirm that cycloalkanes are less reactive than their non-cyclic counterparts. Moreover, cyclopentane, a high octane number and high octane sensitivity fuel, exhibits minimal low-temperature chemistry and is considerably less reactive than cyclohexane. This study presents the first experimental low-temperature ignition delay data of cyclopentane, a potential fuel-blending component of particular interest due to its desirable antiknock characteristics.

Visual analysis of inter-process communication for large-scale parallel computing.

Science.gov (United States)

Muelder, Chris; Gygi, Francois; Ma, Kwan-Liu

2009-01-01

In serial computation, program profiling is often helpful for optimization of key sections of code. When moving to parallel computation, not only does the code execution need to be considered but also communication between the different processes which can induce delays that are detrimental to performance. As the number of processes increases, so does the impact of the communication delays on performance. For large-scale parallel applications, it is critical to understand how the communication impacts performance in order to make the code more efficient. There are several tools available for visualizing program execution and communications on parallel systems. These tools generally provide either views which statistically summarize the entire program execution or process-centric views. However, process-centric visualizations do not scale well as the number of processes gets very large. In particular, the most common representation of parallel processes is a Gantt char t with a row for each process. As the number of processes increases, these charts can become difficult to work with and can even exceed screen resolution. We propose a new visualization approach that affords more scalability and then demonstrate it on systems running with up to 16,384 processes.

Delays in using chromatic and luminance information to correct rapid reaches.

Science.gov (United States)

Kane, Adam; Wade, Alex; Ma-Wyatt, Anna

2011-09-07

People can use feedback to make online corrections to movements but only if there is sufficient time to integrate the new information and make the correction. A key variable in this process is therefore the speed at which the new information about the target location is coded. Conduction velocities for chromatic signals are lower than for achromatic signals so it may take longer to correct reaches to chromatic stimuli. In addition to this delay, the sensorimotor system may prefer achromatic information over the chromatic information as delayed information may be less valuable when movements are made under time pressure. A down-weighting of chromatic information may result in additional latencies for chromatically directed reaches. In our study, participants made online corrections to reaches to achromatic, (L-M)-cone, and S-cone stimuli. Our chromatic stimuli were carefully adjusted to minimize stimulation of achromatic pathways, and we equated stimuli both in terms of detection thresholds and also by their estimated neural responses. Similar stimuli were used throughout the subjective adjustments and final reaching experiment. Using this paradigm, we found that responses to achromatic stimuli were only slightly faster than responses to (L-M)-cone and S-cone stimuli. We conclude that the sensorimotor system treats chromatic and achromatic information similarly and that the delayed chromatic responses primarily reflect early conduction delays.

Measuring Changes in Social Communication Behaviors: Preliminary Development of the Brief Observation of Social Communication Change (BOSCC).

Science.gov (United States)

Grzadzinski, Rebecca; Carr, Themba; Colombi, Costanza; McGuire, Kelly; Dufek, Sarah; Pickles, Andrew; Lord, Catherine

2016-07-01

Psychometric properties and initial validity of the Brief Observation of Social Communication Change (BOSCC), a measure of treatment-response for social-communication behaviors, are described. The BOSCC coding scheme is applied to 177 video observations of 56 young children with ASD and minimal language abilities. The BOSCC has high to excellent inter-rater and test-retest reliability and shows convergent validity with measures of language and communication skills. The BOSCC Core total demonstrates statistically significant amounts of change over time compared to a no change alternative while the ADOS CSS over the same period of time did not. This work is a first step in the development of a novel outcome measure for social-communication behaviors with applications to clinical trials and longitudinal studies.

Estimating power capability of aged lithium-ion batteries in presence of communication delays

Science.gov (United States)

Fridholm, Björn; Wik, Torsten; Kuusisto, Hannes; Klintberg, Anton

2018-04-01

Efficient control of electrified powertrains requires accurate estimation of the power capability of the battery for the next few seconds into the future. When implemented in a vehicle, the power estimation is part of a control loop that may contain several networked controllers which introduces time delays that may jeopardize stability. In this article, we present and evaluate an adaptive power estimation method that robustly can handle uncertain health status and time delays. A theoretical analysis shows that stability of the closed loop system can be lost if the resistance of the model is under-estimated. Stability can, however, be restored by filtering the estimated power at the expense of slightly reduced bandwidth of the signal. The adaptive algorithm is experimentally validated in lab tests using an aged lithium-ion cell subject to a high power load profile in temperatures from -20 to +25 °C. The upper voltage limit was set to 4.15 V and the lower voltage limit to 2.6 V, where significant non-linearities are occurring and the validity of the model is limited. After an initial transient when the model parameters are adapted, the prediction accuracy is within ± 2 % of the actually available power.

Representing delayed force feedback as a combination of current and delayed states.

Science.gov (United States)

Avraham, Guy; Mawase, Firas; Karniel, Amir; Shmuelof, Lior; Donchin, Opher; Mussa-Ivaldi, Ferdinando A; Nisky, Ilana

2017-10-01

To adapt to deterministic force perturbations that depend on the current state of the hand, internal representations are formed to capture the relationships between forces experienced and motion. However, information from multiple modalities travels at different rates, resulting in intermodal delays that require compensation for these internal representations to develop. To understand how these delays are represented by the brain, we presented participants with delayed velocity-dependent force fields, i.e., forces that depend on hand velocity either 70 or 100 ms beforehand. We probed the internal representation of these delayed forces by examining the forces the participants applied to cope with the perturbations. The findings showed that for both delayed forces, the best model of internal representation consisted of a delayed velocity and current position and velocity. We show that participants relied initially on the current state, but with adaptation, the contribution of the delayed representation to adaptation increased. After adaptation, when the participants were asked to make movements with a higher velocity for which they had not previously experienced with the delayed force field, they applied forces that were consistent with current position and velocity as well as delayed velocity representations. This suggests that the sensorimotor system represents delayed force feedback using current and delayed state information and that it uses this representation when generalizing to faster movements. NEW & NOTEWORTHY The brain compensates for forces in the body and the environment to control movements, but it is unclear how it does so given the inherent delays in information transmission and processing. We examined how participants cope with delayed forces that depend on their arm velocity 70 or 100 ms beforehand. After adaptation, participants applied opposing forces that revealed a partially correct representation of the perturbation using the current and the

Consensus of multiple autonomous underwater vehicles with double independent Markovian switching topologies and timevarying delays

International Nuclear Information System (INIS)

Yan Zhe-Ping; Liu Yi-Bo; Zhou Jia-Jia; Zhang Wei; Wang Lu

2017-01-01

A new method in which the consensus algorithm is used to solve the coordinate control problems of leaderless multiple autonomous underwater vehicles (multi-AUVs) with double independent Markovian switching communication topologies and time-varying delays among the underwater sensors is investigated. This is accomplished by first dividing the communication topology into two different switching parts, i.e., velocity and position, to reduce the data capacity per data package sent between the multi-AUVs in the ocean. Then, the state feedback linearization is used to simplify and rewrite the complex nonlinear and coupled mathematical model of the AUVs into a double-integrator dynamic model. Consequently, coordinate control of the multi-AUVs is regarded as an approximating consensus problem with various time-varying delays and velocity and position topologies. Considering these factors, sufficient conditions of consensus control are proposed and analyzed and the stability of the multi-AUVs is proven by Lyapunov–Krasovskii theorem. Finally, simulation results that validate the theoretical results are presented. (paper)

Modulation/demodulation techniques for satellite communications. Part 1: Background

Science.gov (United States)

Omura, J. K.; Simon, M. K.

1981-01-01

Basic characteristics of digital data transmission systems described include the physical communication links, the notion of bandwidth, FCC regulations, and performance measurements such as bit rates, bit error probabilities, throughputs, and delays. The error probability performance and spectral characteristics of various modulation/demodulation techniques commonly used or proposed for use in radio and satellite communication links are summarized. Forward error correction with block or convolutional codes is also discussed along with the important coding parameter, channel cutoff rate.

Decoding Delay Controlled Completion Time Reduction in Instantly Decodable Network Coding

KAUST Repository

Douik, Ahmed

2016-06-27

For several years, the completion time and the decoding delay problems in Instantly Decodable Network Coding (IDNC) were considered separately and were thought to act completely against each other. Recently, some works aimed to balance the effects of these two important IDNC metrics but none of them studied a further optimization of one by controlling the other. This paper investigates the effect of controlling the decoding delay to reduce the completion time below its currently best-known solution in both perfect and imperfect feedback with persistent erasure channels. To solve the problem, the decodingdelay- dependent expressions of the users’ and overall completion times are derived in the complete feedback scenario. Although using such expressions to find the optimal overall completion time is NP-hard, the paper proposes two novel heuristics that minimizes the probability of increasing the maximum of these decoding-delay-dependent completion time expressions after each transmission through a layered control of their decoding delays. Afterward, the paper extends the study to the imperfect feedback scenario in which uncertainties at the sender affects its ability to anticipate accurately the decoding delay increase at each user. The paper formulates the problem in such environment and derives the expression of the minimum increase in the completion time. Simulation results show the performance of the proposed solutions and suggest that both heuristics achieves a lower mean completion time as compared to the best-known heuristics for the completion time reduction in perfect and imperfect feedback. The gap in performance becomes more significant as the erasure of the channel increases.

Decoding Delay Controlled Completion Time Reduction in Instantly Decodable Network Coding

KAUST Repository

Douik, Ahmed S.; Sorour, Sameh; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

2016-01-01

For several years, the completion time and the decoding delay problems in Instantly Decodable Network Coding (IDNC) were considered separately and were thought to act completely against each other. Recently, some works aimed to balance the effects of these two important IDNC metrics but none of them studied a further optimization of one by controlling the other. This paper investigates the effect of controlling the decoding delay to reduce the completion time below its currently best-known solution in both perfect and imperfect feedback with persistent erasure channels. To solve the problem, the decodingdelay- dependent expressions of the users’ and overall completion times are derived in the complete feedback scenario. Although using such expressions to find the optimal overall completion time is NP-hard, the paper proposes two novel heuristics that minimizes the probability of increasing the maximum of these decoding-delay-dependent completion time expressions after each transmission through a layered control of their decoding delays. Afterward, the paper extends the study to the imperfect feedback scenario in which uncertainties at the sender affects its ability to anticipate accurately the decoding delay increase at each user. The paper formulates the problem in such environment and derives the expression of the minimum increase in the completion time. Simulation results show the performance of the proposed solutions and suggest that both heuristics achieves a lower mean completion time as compared to the best-known heuristics for the completion time reduction in perfect and imperfect feedback. The gap in performance becomes more significant as the erasure of the channel increases.

Smartphone-assisted minimally invasive neurosurgery.

Science.gov (United States)

Mandel, Mauricio; Petito, Carlo Emanuel; Tutihashi, Rafael; Paiva, Wellingson; Abramovicz Mandel, Suzana; Gomes Pinto, Fernando Campos; Ferreira de Andrade, Almir; Teixeira, Manoel Jacobsen; Figueiredo, Eberval Gadelha

2018-03-13

OBJECTIVE Advances in video and fiber optics since the 1990s have led to the development of several commercially available high-definition neuroendoscopes. This technological improvement, however, has been surpassed by the smartphone revolution. With the increasing integration of smartphone technology into medical care, the introduction of these high-quality computerized communication devices with built-in digital cameras offers new possibilities in neuroendoscopy. The aim of this study was to investigate the usefulness of smartphone-endoscope integration in performing different types of minimally invasive neurosurgery. METHODS The authors present a new surgical tool that integrates a smartphone with an endoscope by use of a specially designed adapter, thus eliminating the need for the video system customarily used for endoscopy. The authors used this novel combined system to perform minimally invasive surgery on patients with various neuropathological disorders, including cavernomas, cerebral aneurysms, hydrocephalus, subdural hematomas, contusional hematomas, and spontaneous intracerebral hematomas. RESULTS The new endoscopic system featuring smartphone-endoscope integration was used by the authors in the minimally invasive surgical treatment of 42 patients. All procedures were successfully performed, and no complications related to the use of the new method were observed. The quality of the images obtained with the smartphone was high enough to provide adequate information to the neurosurgeons, as smartphone cameras can record images in high definition or 4K resolution. Moreover, because the smartphone screen moves along with the endoscope, surgical mobility was enhanced with the use of this method, facilitating more intuitive use. In fact, this increased mobility was identified as the greatest benefit of the use of the smartphone-endoscope system compared with the use of the neuroendoscope with the standard video set. CONCLUSIONS Minimally invasive approaches

Communicative-Pragmatic Typology of Irony-Effect with the Strategic Ambivalence within the English and Ukrainian Language Traditions

Directory of Open Access Journals (Sweden)

Hnatiuk Lubomira

2016-12-01

Full Text Available Background: The research of ambivalence is an actual problem of modern linguistics because of active promotion of Strategic Ambiguity as one of the key pragmatic categories on the way to understand the complexity of the concept of communicative intentions of the speaker. Generalization of conceptual and terminological findings in the Hinting Strategy of ironical utterances allows to develop the appropriate models of their practical application in the interpersonal interaction. Purpose: The purpose of the investigation is to determine the qualifying and classifying features of the irony-effect in order to demonstrate the importance of strategic ambiguity and propose a model for determining the strategically ambiguous communication. The main task of the article is to investigate the strategic ambivalence as one of the key categories of pragmatics toward understanding the complexity of the concept of intention in the speaker's communication and analyze different types of strategic ambiguity in the ironic utterances as well as the mechanisms of optimization of interpersonal interaction on the factual material of English and Ukrainian languages. Results: In the research the term strategic ambivalence refers to those communicative situations where interlocutors use ambiguity purposefully to accomplish their goals. Strategic ambiguity may be particularly useful in the interpersonal interaction. Under the circumstances of the Hinting Strategy communicative acts are often intentionally ambiguous since they allow different interpretations to coexist and therefore they are more effective in the interpersonal interaction. The communicative acts within ironical utterances are unclear and ambiguous. Although clarity is usually considered desirable for interpersonal communication, ambiguity may be more effective under the circumstances of the Hinting Stategy. Discussion: The strategic use of ambiguity minimizes the impolite speech acts. Another important

On the Secrecy Degrees of Freedom with Full-Duplex Communication

DEFF Research Database (Denmark)

Mahmood, Nurul Huda; Mogensen, Preben Elgaard

2017-01-01

of such an application. The potential of full duplex nodes in improving the physical layer security of a communication link is investigated in this contribution. We specifically derive the information theoretic secrecy degrees of freedom measure for a pair of nodes communicating in full duplex mode. Moreover, closed...... and the delay reduction of full duplex communication are somewhat limited in realistic network settings, leading researchers to study other possible applications of full duplex communication which can provide significantly higher gains over half duplex communication. Physical layer security is an example...... form expressions for the instantaneous and ergodic throughput gain of full duplex communication over conventional half duplex is derived. The secrecy degrees of freedom with full duplex is shown to be two as opposed to that of zero in half duplex mode....

Multiple relay selection for delay-limited applications

KAUST Repository

Alsharoa, Ahmad M.

2013-12-01

A multiple relay selection system model that implements the decode-and-forward mode is investigated. All communication nodes are assumed to be equipped by multiple antennas. Furthermore, lattices space-time coded multiple-input multiple-output half duplex channel is applied. The main goal is to increase the throughput of the system by selecting multiple number of relays. The selection criteria depends on the maximum decoding delay at relays where the system implements a decoding time-out algorithm at each relay. This leads to a significant saving in the overall system power consumptions and attempts to solve the relays synchronization problem. All results are presented using numerical simulations. © 2012 IEEE.

The TCD50 and regrowth delay assay in human tumor xenografts: Differences and implications

International Nuclear Information System (INIS)

Budach, W.; Budach, V.; Stuschke, M.; Dinges, S.; Sack, H.

1993-01-01

The response to irradiation of five human xenograft cell lines - a malignant paraganglioma, a neurogenic sarcoma, a malignant histiocytoma, a primary lymphoma of the brain, and a squamous cell carcinoma - were tested in nude mice. All mice underwent 5 Gy whole body irradiation prior to xenotransplantation to minimize the residual immune response. The subcutaneous tumors were irradiated at a tumor volume of 120 mm 3 under acutely hypoxic conditions with single doses between 8 Gy and 80 Gy depending on the expected radiation sensitivity of the tumor line. Endpoints of the study were the tumor control dose 50% (TCD 50 ) and the regrowth delay endpoints growth delay, specific growth delay, and the tumor bed effect corrected specific growth delay. Specific growth delay and corrected specific growth delay at 76% of the TCD 50 was used in order to compare the data to previously published data from spheroids. The lowest TCD 50 was found in the lymphoma with 24.9 Gy, whereas the TCD 50 of the soft tissue sarcomas and the squamous cell carcinoma ranged from 57.8 Gy to 65.6 Gy. The isoeffective dose levels for the induction of 30 days growth delay, a specific growth delay of 3, and a corrected specific growth delay of 3 ranged from 15.5 Gy (ECL1) to 37.1 Gy (FADU), from 7.2 Gy (ENE2) to 45.6 Gy (EPG1) and from 9.2 Gy (ENE2) to 37.6 Gy (EPG1), respectively. The corrected specific growth delay at 76% of the TCD 50 was correlated with the number of tumor rescue units per 100 cells in spheroids, which was available for three tumor lines, and with the tumor doubling time in xenografts (n = 5). The TCD 50 values corresponded better to the clinical experience than the regrowth delay data. There was no correlation between TCD 50 and any of the regrowth delay endpoints. This missing correlation was most likely a result of large differences in the number of tumor rescue units in human xenografts of the same size

Stability switches, oscillatory multistability, and spatio-temporal patterns of nonlinear oscillations in recurrently delay coupled neural networks.

Science.gov (United States)

Song, Yongli; Makarov, Valeri A; Velarde, Manuel G

2009-08-01

A model of time-delay recurrently coupled spatially segregated neural assemblies is here proposed. We show that it operates like some of the hierarchical architectures of the brain. Each assembly is a neural network with no delay in the local couplings between the units. The delay appears in the long range feedforward and feedback inter-assemblies communications. Bifurcation analysis of a simple four-units system in the autonomous case shows the richness of the dynamical behaviors in a biophysically plausible parameter region. We find oscillatory multistability, hysteresis, and stability switches of the rest state provoked by the time delay. Then we investigate the spatio-temporal patterns of bifurcating periodic solutions by using the symmetric local Hopf bifurcation theory of delay differential equations and derive the equation describing the flow on the center manifold that enables us determining the direction of Hopf bifurcations and stability of the bifurcating periodic orbits. We also discuss computational properties of the system due to the delay when an external drive of the network mimicks external sensory input.

Asymptotic Delay Analysis for Cross-Layer Delay-Based Routing in Ad Hoc Networks

Directory of Open Access Journals (Sweden)

Philippe Jacquet

2007-01-01

Full Text Available This paper addresses the problem of the evaluation of the delay distribution via analytical means in IEEE 802.11 wireless ad hoc networks. We show that the asymptotic delay distribution can be expressed as a power law. Based on the latter result, we present a cross-layer delay estimation protocol and we derive new delay-distribution-based routing algorithms, which are well adapted to the QoS requirements of real-time multimedia applications. In fact, multimedia services are not sensitive to average delays, but rather to the asymptotic delay distributions. Indeed, video streaming applications drop frames when they are received beyond a delay threshold, determined by the buffer size. Although delay-distribution-based routing is an NP-hard problem, we show that it can be solved in polynomial time when the delay threshold is large, because of the asymptotic power law distribution of the link delays.

Minimally Verbal School-Aged Children with Autism: Communication, Academic Engagement and Classroom Quality

Science.gov (United States)

Krueger, Kathryne Kelley

2013-01-01

Minimally verbal school aged children with autism (MVSACwA) receive the bulk of their behavioral and academic support in schools yet we know little about the environments to which they are exposed. This population of children has often been excluded from studies and thus, underrepresented in current data on autism. As increasing numbers of…

Developmental delays in emotion regulation strategies in preschoolers with autism.

Science.gov (United States)

Nuske, Heather J; Hedley, Darren; Woollacott, Alexandra; Thomson, Phoebe; Macari, Suzanne; Dissanayake, Cheryl

2017-11-01

Children with autism spectrum disorder (ASD) commonly present with difficulty regulating negative emotions, which has been found to impact their behavioral and mental health. Little research has documented the strategies that children with ASD use to regulate their emotion to understand whether they use qualitatively different strategies to children without ASD, whether these are developmentally delayed, or both. Forty-four children with ASD and 29 typically-developing children (2-4 years) were given tasks designed to mimic everyday life experiences requiring children to manage low-level stress (e.g., waiting for a snack) and children's emotion regulation strategies were coded. Parents reported on their child's mental health, wellbeing, and self-development. The results suggest differences in using emotion regulation strategies in children with ASD, reflecting a delay, rather than a deviance when compared to those used by children without ASD. Only children with ASD relied on their family members for physical and communicative soothing; the typically developing children relied on people outside of their family for help regulating their emotion. More frequent approach/less frequent avoidance was related to a higher self-evaluation in both groups, but was only additionally related to higher self-recognition and autonomy in the ASD group. These findings help to identify important emotion regulation intervention targets for this population, including supporting communication with people outside of the family and independence. Autism Res 2017, 10: 1808-1822. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. Results suggest that children with autism had more difficulty using communication strategies to manage stress only with people outside the family; they used these strategies with family members as often as children without autism. For all children, more task approach/less avoidance was related to children's higher self-evaluation. These

Delayed fission

Energy Technology Data Exchange (ETDEWEB)

Hatsukawa, Yuichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1997-07-01

Delayed fission is a nuclear decay process that couples {beta} decay and fission. In the delayed fission process, a parent nucleus undergoes {beta} decay and thereby populates excited states in the daughter. If these states are of energies comparable to or greater than the fission barrier of the daughter, then fission may compete with other decay modes of the excited states in the daughter. In this paper, mechanism and some experiments of the delayed fission will be discussed. (author)

The communication in the sea as efficient tool to minimize the conflicts between seismic survey and fisheries; A comunicacao no mar como ferramenta eficaz de minimizacao dos conflitos entre pesquisa sismica e pesca

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, D.H.X.B.C.; Oliveira, M.R.; Carloni, G.G.; Rezende, A.R. [Ecologus Engenharia Consultiva Ltda., Rio de Janeiro, RJ (Brazil); Uller, G.A. [CGGVeritas, Paris (France)

2008-07-01

In the period from February 14th to July 14th, 2007, CGGVeritas performed marine seismic survey (Class 1), in BM-C-26 and BM-C-27 Blocks, located in the Campos Basin. The Social Communication Project - SCP had as main objectives provide to stakeholders information related to the potential impact generated by the activity and a communication channel with the company. This article is focused on the Direct Contact Strategy, which played the role of making contact with all the fishing vessels sailing on the route of the seismic vessel. This strategy has three functions: to contact the fishing vessels near the seismic vessel; communicate through radio announcements informing the exact position of the seismic vessel and; investigate all incidents. There were 547 fishing vessels contacted of the total 692 observed. Only 5 incidents involving loss of fishing equipment were registered. All potential impacts associated with the seismic survey have been significantly minimized. The successful performance of the assistant boats also assured the great performance of the Project, interrupted a few times due to the presence of fishing vessels. It follows that the strategy was an important factor of success for the Social Communication Project. (author)

Improving Interdisciplinary Provider Communication Through a Unified Paging System.

Science.gov (United States)

Heidemann, Lauren; Petrilli, Christopher; Gupta, Ashwin; Campbell, Ian; Thompson, Maureen; Cinti, Sandro; Stewart, David A

2016-06-01

Interdisciplinary communication at a Veterans Affairs (VA) academic teaching hospital is largely dependent on alphanumeric paging, which has limitations as a result of one-way communication and lack of reliable physician identification. Adverse patient outcomes related to difficulty contacting the correct consulting provider in a timely manner have been reported. House officers were surveyed on the level of satisfaction with the current VA communication system and the rate of perceived adverse patient outcomes caused by potential delays within this system. Respondents were then asked to identify the ideal paging system. These results were used to develop and deploy a new Web site. A postimplementation survey was repeated 1 year later. This study was conducted as a quality improvement project. House officer satisfaction with the preintervention system was 3%. The majority used more than four modalities to identify consultants, with 59% stating that word of mouth was a typical source. The preferred mode of paging was the university hospital paging system, a Web-based program that is used at the partnering academic institution. Following integration of VA consulting services within the university hospital paging system, the level of satisfaction improved to 87%. Significant decreases were seen in perceived adverse patient outcomes (from 16% to 2%), delays in patient care (from 90% to 16%), and extended hospitalizations (from 46% to 4%). Our study demonstrates significant improvement in physician satisfaction with a newly implemented paging system that was associated with a decreased perceived number of adverse patient events and delays in care.

Selective induction of cyclin B protein abrogates the G2 delay after irradiation

International Nuclear Information System (INIS)

Kao, G.; Muschel, R.J.; Maity, A.; Kunig, A.; McKenna, W.G.

1996-01-01

Purpose/Objective: Irradiation of tumor cells commonly results in G2 delay, which has been postulated to allow DNA repair and cell survival. The G2 delay after irradiation is also often marked in some cell lines by delayed expression of cyclin B protein, suggesting a role for cyclin B regulation. Investigations of these hypotheses however has been hampered by the inability to selectively perturb the G2 delay in a physiologic manner. Materials and Methods: We have devised a system, with which we are able to selectively induce cyclin B protein expression in vivo at specific points in the cell cycle, by transfecting Hela cells with an expression vector under control of a dexamethasone-inducible promoter. Experiments were subsequently performed by synchronizing, releasing, irradiating, inducing, and harvesting these cells through the cell cycle. Results: Irradiation with 5 Gy led to a pronounced G2 delay, reflected by markedly slowed progression into mitosis, concomitant with reduced expression of cyclin B protein. Induction of cyclin B after radiation in these cells abrogated the G2 delay by approximately doubling the rate at which the cells re-enter mitosis. Treatment of irradiated untransfected control cells with dexamethasone, in which cyclin B is not induced, led to minimal changes. Studies of effects of cyclin B induction on cyclin B localization (using immunofluorescence), cdc2 phosphorylation and activation will also be presented. Conclusion: This system should allow further investigations into fundamental mechanisms of cell cycle regulation after irradiation and DNA damage. This also provides direct evidence for the first time that cyclin B protein regulation may play a role in the G2 delay following irradiation in Hela cells, perhaps complementing phosphorylation events

Sliding mode load frequency control for multi-area time-delay power system with wind power integration

DEFF Research Database (Denmark)

Mi, Yang; Hao, Xuezhi; Liu, Yongjuan

2017-01-01

The interconnected time-delay power system has become an important issue for the open communication network. Meanwhile, due to the output power fluctuation of integrated wind energy, load frequency control (LFC) for power system with variable sources and loads has become more complicated. The novel...

Analysis, Synthesis and Experiments of Networked Platoons with Communication Constraints

Directory of Open Access Journals (Sweden)

Ligang Wu

2017-02-01

Full Text Available This paper investigates the analysis and synthesis of networked vehicle platoons with communication delays, packet dropouts and disorders. In order to deal with the effects of the communication constraints, we introduce a novel Smart Data Processor (SDP for each vehicle, by which the latest data packets from logic Data Packet Processor and the matched data packet from its Buffer can be obtained. Based on this mechanism, a leader-predecessor-follower control strategy is proposed. In order to guarantee the asymptotic and string stability, the platoon control problem is transformed into a multi-objective H∞-type synthesis problem with the multiple time-varying delays. A sufficient condition for designing the controller gain is derived by solving a set of linear matrix inequalities. Numerous simulations and experiments with laboratory scale Arduino cars show the efficiency of the proposed methods.

Globally Deghosting for Marine Streamer with Alternating Minimization Approach in Frequency-slowness Domain

Science.gov (United States)

Wang, C.; Zhu, Z.; Gu, H.; Liu, C.; Liu, Z.; Jiao, Z.

2017-12-01

The ghost effects of the sea surface can generate notch in marine towed-streamer data, which results in narrow bandwidth of seismic data. Currently, deghosting is widely utilized to increase the bandwidth of the seismic data or the images. However, most of the conventional deghosting algorithms havenot considered the error of streamer depth causing a biased ghost-delay time (τ) with respect to primary reflection and amplitude difference coefficient (r) between ghost and primary reflection varies with offset due to rugged seabed and target depth variation. We proposed a ghost filtering operator considering the protentional biases within the ghost-delay time (τ) and the amplitude difference coefficient (r). The up-going wavefield (u), ghost-delay time (τ) and amplitude difference coefficient (r) can be obtained by utilizing alternating minimization approach for minimizing the difference between actual wavefield and theoretical wavefield in frequency-slowness domain. The main idea is to alternatively updating u, τ and r in each iteration: we update u by least-squares when we keep τ and r constant; and we then keep u constant and optimize over τ and r with a closed-form solution which is closely related to matched filtering. The convergence of the proposed algorithm is guaranteed since we have closed-form solutions for each stage. The experiments on synthetic record confirmed the reliability of the proposed algorithm. We also demonstrate our proposed method in marine VDS shot acquisition. After migration stack processing, our ghosting method significantly increases the bandwidth of the average amplitude, amplitude energy of the medium and high frequency spectrum, improving resolution of medium and deep reflection and providing higher signal-to-noise ratio with clear break point. This research is funded by China Important National Science & Technology Specific Projects (2016ZX05026001-001).

Dynamic Routing for Delay-Tolerant Networking in Space Flight Operations

Science.gov (United States)

Burleigh, Scott C.

2008-01-01

Contact Graph Routing (CGR) is a dynamic routing system that computes routes through a time-varying topology composed of scheduled, bounded communication contacts in a network built on the Delay-Tolerant Networking (DTN) architecture. It is designed to support operations in a space network based on DTN, but it also could be used in terrestrial applications where operation according to a predefined schedule is preferable to opportunistic communication, as in a low-power sensor network. This paper will describe the operation of the CGR system and explain how it can enable data delivery over scheduled transmission opportunities, fully utilizing the available transmission capacity, without knowing the current state of any bundle protocol node (other than the local node itself) and without exhausting processing resources at any bundle router.

Response to 'Decades of delay in nuclear waste disposal - a failure to communicate'

International Nuclear Information System (INIS)

Nagasaki, S.

2014-01-01

In a recent opinion piece on the delay of nuclear waste disposal, Mr. H. Tammemagi asserts that it is important for a nuclear community to include in the Canadian public discourse the presence of natural radiation, comparisons between radioactive and non-radioactive wastes, and nuclear medicine. It is to the first two that I respond to, with the view that the lessons learnt from Japan have merit for addressing the issues in the Canadian context. (author)

Consensus of discrete-time multi-agent systems with adversaries and time delays

Science.gov (United States)

Wu, Yiming; He, Xiongxiong; Liu, Shuai; Xie, Lihua

2014-05-01

This paper studies the resilient asymptotic consensus problem for discrete-time multi-agent systems in the presence of adversaries and transmission delays. The network is assumed to have ? loyal agents and ? adversarial agents, and each loyal agent in the network has no knowledge of the network topology other than an upper bound on the number of adversarial agents in its neighborhood. For the considered networked system, only locally delayed information is available for each loyal agent, and also the information flow is directed and a control protocol using only local information is designed to guarantee the realization of consensus with respect to communication graph, which satisfies a featured network robustness. Numerical examples are finally given to demonstrate the effectiveness of theoretical results.

Active power reference tracking in electricity distribution grids over non-ideal communication networks

DEFF Research Database (Denmark)

Kristensen, Thomas le Fevre; Olsen, Rasmus Løvenstein; Iov, Florin

2018-01-01

the distributed implementation in the testbed show the effectiveness of the controller and that the considered scenario of the reference tracking application is not significantly affected by delays and losses as originating from PLC communication in good conditions. The subsequent simulation experiments show......Distribution system operators may in the future control active power of selected consumers and generators in order to achieve a desired grid behavior. For cost efficient deployment, this control application may use existing communication infrastructure with non-ideal properties, i.e. imposing...... the resilience of the reference tracking control application to end-to-end message delays up to the order of 3 control periods and to message loss up to approximately 70%....

Predictive scheduling approach in Inter-piconet communications

DEFF Research Database (Denmark)

Son, L.T.; Schiøler, Henrik; Madsen, Ole Brun

2001-01-01

mobile devices. Originally it was developed as cable replacement. For the time being, it has been used as a mobile ad hoc network, which is intended for both voice and data communications, e.g. voice traffics, TCP/IP data traffics.. . Knowledge on mobile ad hoc network will be in need of studying...... delivered to end users in Bluetooth networks depends on large number of parameters at different levels, e.g. link capacity, packet delays.., which require various control and optimization methods. In this pa-per, an important part of inter-connected communications, inter-piconet scheduling, is mentioned...

Predictive scheduling approach in Inter-piconet communications

DEFF Research Database (Denmark)

Son, L.T.; Schiøler, Henrik; Madsen, Ole Brun

mobile devices. Originally it was developed as cable replacement. For the time being, it has been used as a mobile ad hoc network, which is intended for both voice and data communications, e.g. voice traffics, TCP/IP data traffics.. . Knowledge on mobile ad hoc network will be in need of studying...... delivered to end users in Bluetooth networks depends on large number of parameters at different levels, e.g. link capacity, packet delays.., which require various control and optimization methods. In this pa-per, an important part of inter-connected communications, inter-piconet scheduling, is mentioned...

Delays in nuclear power plant construction. Volume II. Final report

International Nuclear Information System (INIS)

Mason, G.E.; Larew, R.E.; Borcherding, J.D.; Okes, S.R. Jr.; Rad, P.F.

1977-01-01

The report identifies barriers to shortening nuclear power plant construction schedules and recommends research efforts which should minimize or eliminate the identified barriers. The identified barriers include (1) Design and Construction Interfacing Problems; (2) Problems Relating to the Selection and Use of Permanent Materials and Construction Methods; (3) Construction Coordination and Communication Problems; and (4) Problems Associated with Manpower Availability and Productivity

Delays in nuclear power plant construction. Volume I. Final report

International Nuclear Information System (INIS)

1977-01-01

The report identifies barriers to shortening nuclear power plant construction schedules and recommends research efforts which should minimize or eliminate the identified barriers. The identified barriers include: (1) Design and Construction Interfacing Problems; (2) Problems Relating to the Selection and Use of Permanent Materials and Construction Methods; (3) Construction Coordination and Communication Problems; and (4) Problems Associated with Manpower Availability and Productivity

Oral motor functions, speech and communication before a definitive diagnosis of amyotrophic lateral sclerosis.

Science.gov (United States)

Makkonen, Tanja; Korpijaakko-Huuhka, Anna-Maija; Ruottinen, Hanna; Puhto, Riitta; Hollo, Kirsi; Ylinen, Aarne; Palmio, Johanna

2016-01-01

The aim of this study was to explore the cranial nerve symptoms, speech disorders and communicative effectiveness of Finnish patients with diagnosed or possible amyotrophic lateral sclerosis (ALS) at their first assessment by a speech-language pathologist. The group studied consisted of 30 participants who had clinical signs of bulbar deterioration at the beginning of the study. They underwent a thorough clinical speech and communication examination. The cranial nerve symptoms and ability to communicate were compared in 14 participants with probable or definitive ALS and in 16 participants with suspected or possible ALS. The initial type of ALS was also assessed. More deterioration in soft palate function was found in participants with possible ALS than with diagnosed ALS. Likewise, a slower speech rate combined with more severe dysarthria was observed in possible ALS. In both groups, there was some deterioration in communicative effectiveness. In the possible ALS group the diagnostic delay was longer and speech therapy intervention actualized later. The participants with ALS showed multidimensional decline in communication at their first visit to the speech-language pathologist, but impairments and activity limitations were more severe in suspected or possible ALS. The majority of persons with bulbar-onset ALS in this study were in the latter diagnostic group. This suggests that they are more susceptible to delayed diagnosis and delayed speech therapy assessment. It is important to start speech therapy intervention during the diagnostic processes particularly if the person already shows bulbar symptoms. Copyright © 2016. Published by Elsevier Inc.

Chlorpyrifos-Induced Delayed Neurotoxicity with A Rare Presentation of Flaccid Quadriplegia: A Diagnostic Challenge

Directory of Open Access Journals (Sweden)

Patrícia Afonso Mendes

2017-10-01

Full Text Available Chlorpyrifos is an organophosphate compound recognized as causing acute toxicity. However, organophosphate-induced delayed polyneuropathy (OPIDP, although rare, has also been described. We describe an unusual presentation of OPIDP with flaccid quadriplegia progressing to a locked-in-like syndrome, 30 days after a 60-year-old man voluntarily ingested chlorpyrifos. In the absence of specific treatment, the patient only recovered partial motor responses and the ability to communicate. The authors present this report in order to highlight a form of OPIDP which can hinder diagnosis due to its atypia and the delay in the onset of symptoms from initial contact with the toxicant.

Throughput and delay analysis of IEEE 802.15.6-based CSMA/CA protocol.

Science.gov (United States)

Ullah, Sana; Chen, Min; Kwak, Kyung Sup

2012-12-01

The IEEE 802.15.6 is a new communication standard on Wireless Body Area Network (WBAN) that focuses on a variety of medical, Consumer Electronics (CE) and entertainment applications. In this paper, the throughput and delay performance of the IEEE 802.15.6 is presented. Numerical formulas are derived to determine the maximum throughput and minimum delay limits of the IEEE 802.15.6 for an ideal channel with no transmission errors. These limits are derived for different frequency bands and data rates. Our analysis is validated by extensive simulations using a custom C+ + simulator. Based on analytical and simulation results, useful conclusions are derived for network provisioning and packet size optimization for different applications.

A TOTP-based enhanced route optimization procedure for mobile IPv6 to reduce handover delay and signalling overhead.

Science.gov (United States)

Shah, Peer Azmat; Hasbullah, Halabi B; Lawal, Ibrahim A; Aminu Mu'azu, Abubakar; Tang Jung, Low

2014-01-01

Due to the proliferation of handheld mobile devices, multimedia applications like Voice over IP (VoIP), video conferencing, network music, and online gaming are gaining popularity in recent years. These applications are well known to be delay sensitive and resource demanding. The mobility of mobile devices, running these applications, across different networks causes delay and service disruption. Mobile IPv6 was proposed to provide mobility support to IPv6-based mobile nodes for continuous communication when they roam across different networks. However, the Route Optimization procedure in Mobile IPv6 involves the verification of mobile node's reachability at the home address and at the care-of address (home test and care-of test) that results in higher handover delays and signalling overhead. This paper presents an enhanced procedure, time-based one-time password Route Optimization (TOTP-RO), for Mobile IPv6 Route Optimization that uses the concepts of shared secret Token, time based one-time password (TOTP) along with verification of the mobile node via direct communication and maintaining the status of correspondent node's compatibility. The TOTP-RO was implemented in network simulator (NS-2) and an analytical analysis was also made. Analysis showed that TOTP-RO has lower handover delays, packet loss, and signalling overhead with an increased level of security as compared to the standard Mobile IPv6's Return-Routability-based Route Optimization (RR-RO).

A TOTP-Based Enhanced Route Optimization Procedure for Mobile IPv6 to Reduce Handover Delay and Signalling Overhead

Science.gov (United States)

Shah, Peer Azmat; Hasbullah, Halabi B.; Lawal, Ibrahim A.; Aminu Mu'azu, Abubakar; Tang Jung, Low

2014-01-01

Due to the proliferation of handheld mobile devices, multimedia applications like Voice over IP (VoIP), video conferencing, network music, and online gaming are gaining popularity in recent years. These applications are well known to be delay sensitive and resource demanding. The mobility of mobile devices, running these applications, across different networks causes delay and service disruption. Mobile IPv6 was proposed to provide mobility support to IPv6-based mobile nodes for continuous communication when they roam across different networks. However, the Route Optimization procedure in Mobile IPv6 involves the verification of mobile node's reachability at the home address and at the care-of address (home test and care-of test) that results in higher handover delays and signalling overhead. This paper presents an enhanced procedure, time-based one-time password Route Optimization (TOTP-RO), for Mobile IPv6 Route Optimization that uses the concepts of shared secret Token, time based one-time password (TOTP) along with verification of the mobile node via direct communication and maintaining the status of correspondent node's compatibility. The TOTP-RO was implemented in network simulator (NS-2) and an analytical analysis was also made. Analysis showed that TOTP-RO has lower handover delays, packet loss, and signalling overhead with an increased level of security as compared to the standard Mobile IPv6's Return-Routability-based Route Optimization (RR-RO). PMID:24688398

Fuzzy delay model based fault simulator for crosstalk delay fault test ...

Indian Academy of Sciences (India)

In this paper, a fuzzy delay model based crosstalk delay fault simulator is proposed. As design .... To find the quality of non-robust tests, a fuzzy delay ..... Dubois D and Prade H 1989 Processing Fuzzy temporal knowledge. IEEE Transactions ...

Delayed power analysis

International Nuclear Information System (INIS)

Adamovich, L.A.; Azarov, V.V.

1999-01-01

Time dependent core power behavior in a nuclear reactor is described with well-known neutron kinetics equations. At the same time, two portions are distinguished in energy released from uranium nuclei fission; one released directly at fission and another delayed (residual) portion produced during radioactive decay of fission products. While prompt power is definitely described with kinetics equations, the delayed power presentation still remains outstanding. Since in operation the delayed power part is relatively small (about 6%) operation, it can be neglected for small reactivity disturbances assuming that entire power obeys neutron kinetics equations. In case of a high negative reactivity rapidly inserted in core (e.g. reactor scram initiation) the prompt and delayed components can be calculated separately with practically no impact on each other, employing kinetics equations for prompt power and known approximation formulas for delayed portion, named residual in this specific case. Under substantial disturbances the prompt component in the dynamic process becomes commensurable with delayed portion, thus making necessary to take into account their cross impact. A system of differential equations to describe time-dependent behavior of delayed power is presented. Specific NPP analysis shows a way to significantly simplify the task formulation. (author)

The generalisation effects of picture exchange communication system (pecs) training for children with autism and language delay

OpenAIRE

Yoon, Jung ae

2017-01-01

The Picture Exchange Communication System (PECS) has been widely used in intervention programs to develop functional communication for children who have no or little vocal communication. Studies have shown that PECS training is effective in developing communication and social interaction (Carr & Felce, 2006; Ganz, Simpson, & Corbin-Newsome, 2007) for children with autism. However, most research on the effectiveness of PECS has been limited in several ways. Firstly, few studies have evaluated ...

Urban sprawl and delayed ambulance arrival in the U.S.

Science.gov (United States)

Trowbridge, Matthew J; Gurka, Matthew J; O'Connor, Robert E

2009-11-01

Minimizing emergency medical service (EMS) response time is a central objective of prehospital care, yet the potential influence of built environment features such as urban sprawl on EMS system performance is often not considered. This study measures the association between urban sprawl and EMS response time to test the hypothesis that features of sprawling development increase the probability of delayed ambulance arrival. In 2008, EMS response times for 43,424 motor-vehicle crashes were obtained from the Fatal Analysis Reporting System, a national census of crashes involving > or =1 fatality. Sprawl at each crash location was measured using a continuous county-level index previously developed by Ewing et al. The association between sprawl and the probability of a delayed ambulance arrival (> or =8 minutes) was then measured using generalized linear mixed modeling to account for correlation among crashes from the same county. Urban sprawl is significantly associated with increased EMS response time and a higher probability of delayed ambulance arrival (p=0.03). This probability increases quadratically as the severity of sprawl increases while controlling for nighttime crash occurrence, road conditions, and presence of construction. For example, in sprawling counties (e.g., Fayette County GA), the probability of a delayed ambulance arrival for daytime crashes in dry conditions without construction was 69% (95% CI=66%, 72%) compared with 31% (95% CI=28%, 35%) in counties with prominent smart-growth characteristics (e.g., Delaware County PA). Urban sprawl is significantly associated with increased EMS response time and a higher probability of delayed ambulance arrival following motor-vehicle crashes in the U.S. The results of this study suggest that promotion of community design and development that follows smart-growth principles and regulates urban sprawl may improve EMS performance and reliability.

Shared identity is key to effective communication.

Science.gov (United States)

Greenaway, Katharine H; Wright, Ruth G; Willingham, Joanne; Reynolds, Katherine J; Haslam, S Alexander

2015-02-01

The ability to communicate with others is one of the most important human social functions, yet communication is not always investigated from a social perspective. This research examined the role that shared social identity plays in communication effectiveness using a minimal group paradigm. In two experiments, participants constructed a model using instructions that were said to be created by an ingroup or an outgroup member. Participants made models of objectively better quality when working from communications ostensibly created by an ingroup member (Experiments 1 and 2). However, this effect was attenuated when participants were made aware of a shared superordinate identity that included both the ingroup and the outgroup (Experiment 2). These findings point to the importance of shared social identity for effective communication and provide novel insights into the social psychology of communication. © 2014 by the Society for Personality and Social Psychology, Inc.

Delay/Disruption Tolerant Networks (DTN): Testing and Demonstration for Lunar Surface Applications

Science.gov (United States)

2009-01-01

This slide presentation reviews the testing of the Delay/Disruption Tolerant Network (DTN) designed for use with Lunar Surface applications. This is being done through the DTN experimental Network (DEN), that permit access and testing by other NASA centers, DTN team members and protocol developers. The objective of this work is to demonstrate DTN for high return applications in lunar scenarios, provide DEN connectivity with analogs of Constellation elements, emulators, and other resources from DTN Team Members, serve as a wireless communications staging ground for remote analog excursions and enable testing of detailed communication scenarios and evaluation of network performance. Three scenarios for DTN on the Lunar surface are reviewed: Motion imagery, Voice and sensor telemetry, and Navigation telemetry.

Longitudinal effects of adaptive interventions with a speech-generating devicein minimally verbal children with ASD

Science.gov (United States)

Almirall, Daniel; DiStefano, Charlotte; Chang, Ya-Chih; Shire, Stephanie; Kaiser, Ann; Lu, Xi; Nahum-Shani, Inbal; Landa, Rebecca; Mathy, Pamela; Kasari, Connie

2016-01-01

Objective There are limited data on the effects of adaptive social communication interventions with a speech-generating device in autism. This study is the first to compare growth in communications outcomes among three adaptive interventions in school-aged children with autism spectrum disorder (ASD) who are minimally verbal. Methods Sixty-one children, aged 5–8 years participated in a sequential, multiple-assignment randomized trial (SMART). All children received a developmental communication intervention: joint attention, symbolic play, engagement and regulation (JASP) with enhanced milieu teaching (EMT). The SMART included three two-stage, 24-week adaptive interventions with different provisions of a speech-generating device (SGD) in the context of JASP+EMT. The first adaptive intervention, with no SGD, initially assigned JASP+EMT alone; then intensified JASP+EMT for slow responders. In the second adaptive intervention, slow responders to JASP+EMT were assigned JASP+EMT+SGD. The third adaptive intervention initially assigned JASP+EMT+SGD; then intensified JASP+EMT+SGD for slow responders. Analyses examined between-group differences in change in outcomes from baseline to week 36. Verbal outcomes included spontaneous communicative utterances and novel words. Non-linguistic communication outcomes included initiating joint attention and behavior regulation, and play. Results The adaptive intervention beginning with JASP+EMT+SGD was estimated as superior. There were significant (Pcommunicative utterances and initiating joint attention. Conclusions School-aged children with ASD who are minimally verbal make significant gains in communication outcomes with an adaptive intervention beginning with JASP+EMT+SGD. Future research should explore mediators and moderators of the adaptive intervention effects and second-stage intervention options that further capitalize on early gains in treatment. PMID:26954267

Asymmetric Propagation Delay-Aware TDMA MAC Protocol for Mobile Underwater Acoustic Sensor Networks

Directory of Open Access Journals (Sweden)

A-Ra Cho

2018-06-01

Full Text Available The propagation delay in mobile underwater acoustic sensor network (MUASN is asymmetric because of its low sound propagation speed, and this asymmetry grows with the increase in packet travel time, which damages the collision avoidance mechanism of the spatial reuse medium access control (MAC protocols for MUASN. We propose an asymmetric propagation delay-aware time division multiple access (APD-TDMA for a MUASN in which periodic data packet transmission is required for a sink node (SN. Collisions at the SN are avoided by deferring data packet transmission after reception of a beacon packet from the SN, and data packets are arrived at the SN in a packet-train manner. The time-offset, which is the time for a node to wait before the transmission of a data packet after reception of a beacon packet, is determined by estimating the propagation delay over two consecutive cycles such that the idle interval at the SN is minimized, and this time-offset is announced by the beacon packet. Simulation results demonstrate that the APD-TDMA improves the channel access delay and the channel utilization by approximately 20% and 30%, respectively, compared with those of the block time bounded TDMA under the given network conditions.

Patient Delay, Diagnosis Delay and Treatment Delay for Breast Cancer: Comparison of the Pattern between Patients in Public and Private Health Sectors

Directory of Open Access Journals (Sweden)

Iraj Harirchi

2015-05-01

Full Text Available Background: The purpose of this study was to compare patient delay, diagnosis delay and treatment delay in breast cancer patients of selected public and private health centers in Tehran, Iran.Methods: In this cross-sectional study, female patients with newly diagnosed breast cancer in a public medical complex and a private breast clinic within one year were included. Patient delay was considered positive, if the interval between the detection of the first symptom by the patient and the first visit to a health care provider took longer than one month. Delay in diagnosis was defined as the period of more than one week between the first medical visit for the symptoms and the diagnosis of breast cancer. Following the confirmed diagnosis of breast malignancy, if the medical treatment was initiated later than one week, treatment delay had occurred. The potential reasons for patient, diagnosis and treatment delay according to the patients’ reports were also recorded.Results: Overall, 385 patients were included of whom 52.7% were recruited from the public hospitals and 47.3% from a private clinic. The prevalence of patient delay, diagnosis delay and treatment delay were 31.7%, 17.9% and 28.3%, respectively. Patient delay was significantly more common among patients with lower socio-economic status and those recruited from the public hospitals. All the patients with diagnosis delay were in the group recruited from the public hospitals.Conclusions: Gaps between women of different socio-economic levels of the society need to be addressed in order to decrease patient, diagnosis and treatment delay.

Speech and Language Delay