Startup Delay Research Articles

Examining links between cognitive markers, movement initiation and change, and pedestrian safety in older adults

ObjectiveThe purpose of this study was to determine the extent to which mobility indices (such as walking speed and postural sway), motor initiation, and cognitive function, specifically executive functions, including spatial planning, visual attention, and within participant variability, differentially predicted collisions in the near and far sides of the road with increasing age. MethodsAdults aged over 45 years participated in cognitive tests measuring executive function and visual attention (using Useful Field of View; UFoV®), mobility assessments (walking speed, sit-to-stand, self-reported mobility, and postural sway assessed using motion capture cameras), and gave road crossing choices in a two-way filmed real traffic pedestrian simulation. ResultsA stepwise regression model of walking speed, start-up delay variability, and processing speed) explained 49.4% of the variance in near-side crossing errors. Walking speed, start-up delay measures (average and variability), and spatial planning explained 54.8% of the variance in far-side unsafe crossing errors. Start-up delay was predicted by walking speed only (explained 30.5%). ConclusionWalking speed and start-up delay measures were consistent predictors of unsafe crossing behaviours. Cognitive measures, however, differentially predicted near-side errors (processing speed), and far-side errors (spatial planning). These findings offer potential contributions for identifying and rehabilitating at-risk older pedestrians.

An efficient hybrid push-pull methodology for peer-to-peer video live streaming system on mobile broadcasting social media

With the rapid growth of wireless communication technology, the availability of highly flexible and video-friendly mobile terminal platforms (such as smartphones and tablets), the emergence of major video content providers (like YouTube, Ustream, and PPTV, which provide a large catalog of attractive contents), Peer-to-Peer (P2P) live video streaming over the wireless and Internet is becoming more and more attractive to users. One of the main challenges is to provide a good quality of service though the dynamic behavior of the network. Traditionally, tree-based model uses a push method, that broadcaster transfers data to other users. This model has low start-up delay. However, there are two main problems in this method: if the bandwidth of an internal node is low, children nodes may lose data and when an internal node failure, other nodes can't receive data until completing the recovery of the tree. On the other hand, mesh-based model uses a pull method, has low bandwidth of a neighbor node by pulling necessary data from a number of neighbor nodes. However, mesh-based model requires large buffers to support pull data from neighbor peers and there is an adjustment between minimum delay by sending pull request and overhead of whole system. So, both models have their own strengths and weaknesses. This paper proposes a new hybrid push-pull live P2P video streaming protocol called MobileCast that combines the benefits of pull and push mechanisms for live video delivery. We present new topology for P2P network with more stable and provide better video streaming quality. Our main goal is to minimize the network end-to-end delay, startup time, overhead, packet loss compared to the pure mesh networks, pure tree networks and provide a good quality of service though the dynamic behavior of the network.

Enhanced Chunk Regulation Algorithm for Superior QoS in Heterogeneous P2P Video on Demand

Traditionally, Video-on-Demand (VoD) systems were based on servers that streamed video contents to the end users. Later, data replication using Content Delivery Networks (CDN) came into existence; this reduced the overall network load by effectively distributing contents to end user. However, replication using CDN is relatively costly. Today, Peer-to-Peer (P2P) based VoD systems have gained wide popularity due to its robustness, scalability and availability. P2P networks consist of a large number of nodes, including mobile devices that join and leave the network frequently. The challenge is to provide better video Quality of Service (QoS) to the end user by making requested copies of video chunks available on demand. In this paper, we propose an Enhanced Chunk Regulation Algorithm (ECRA) for superior video QoS in P2P networks. We propose a chunk selection algorithm called Local Demand based Chunk Download (LDCD) that fulfills the temporal demand of chunks. Our proposed Peer Ranking Factor (PRF) algorithm uses ranking factor to choose the best suitable peers to download video chunks. Additionally, we present Local Demand based Chunk Replication (LDCR) algorithm that considers the demand for particular videos (i.e. movies) in the local cluster. Based on the available bandwidth and cache space the replication of chunks is accomplished such as the QoS of VoD is superior. Our evaluation shows that the proposed algorithm improves the overall end user’s QoS by minimizing missed chunks, stalling delay and startup delay. Moreover, it provides more effective bandwidth utilization and minimizes the load on the source server

Performance evaluation of multiple relays cooperative GBn-ARQ with limited retransmission

We investigate the performance of multiple relays cooperative go back n automatic repeat request(MRC-GBn-ARQ) protocol with limited retransmission. An N +2-state Markov transition model is constructed for analyzing arbitrary packet transmission process with limited retransmission. Then the system’s steadystate distribution is derived by using the Kolmogorov equations.Further, the mean packet transmission delay and startup delay are obtained respectively; the channel utilization is derived based on discrete-time Geom/G/1 queue model with startup. Also, we get the energy efficiency of the MRC-GBn-ARQ based on energy analytical model. Especially, the presented models are contrary to the classical ARQ protocols of always allowing infinite retransmission, and our analysis of the MRC-GBn-ARQ protocol with limited retransmission provides theoretical results for reducing the system’s delay and energy consumption. Finally, analysis is validated through some numerical simulations.

A Novel Energy-Efficiency Social-Inspired Video Sharing Solution in Wireless Networks

Mobile multimedia streaming services provide rich-content visual resources for the mobile users via ubiquitous access to Internet. The video resource sharing focuses on the matching of appropriate resource supplier for the resource requesters and is a key issue for P2P-based video system scalability and user quality of experience. In this context, leveraging social-driven interaction between mobile users enables the discovery of common interests to improve video content sharing efficiency. In this paper, we propose a novel energy-efficiency social-inspired video sharing solution in wireless networks (ESVS). By the analysis of historical request behaviors of users, ESVS designs an estimation method of relationship between videos and groups the videos into a chain-based tree structure. Based on the constructed video tree, ESVS designs a hybrid resource lookup algorithm including push and pull and a communication quality-aware selection strategy of video suppliers, which improves the communication capacities between requesters and suppliers and reduces the network bandwidth consumption. Simulation results also show how ESVS achieves higher resource lookup success rate, lower startup delay, less packet loss rate, and lower maintenance cost than another state-of-the-art solution.

Improving BitTorrent's Peer Selection for Multimedia Content On-Demand Delivery

The great efficiency achieved by the BitTorrent protocol for the distribution of large amounts of data inspired its adoption to provide multimedia content on-demand delivery over the Internet. As it is not designed for this purpose, some adjustments have been proposed in order to meet the related QoS requirements like low startup delay and smooth playback continuity. Accordingly, this paper introduces a BitTorrent-like proposal named as Quota-Based Peer Selection (QBPS). This proposal is mainly based on the adaptation of the original peer-selection policy of the BitTorrent protocol. Its validation is achieved by means of simulations and competitive analysis. The final results show that QBPS outperforms other recent proposals of the literature. For instance, it achieves a throughput optimization of up to 48.0% in low-provision capacity scenarios where users are very interactive.

I2CC: Interleaving two-level cache with network coding in peer-to-peer VoD system

As video technologies have advanced, peer-to-peer video-on-demand services have increasingly proliferated. In this paper, an interleaving two-level cache with network coding (I2CC) scheme is proposed to provide rapid content searching and efficiently support random seeking with the dynamic nature of peers. In I2CC, a video segment is composed of chunks, and each chunk is divided into blocks. These blocks are encoded by a network coding technique and distributed to different peers for storage in a local two-level cache, which includes a prefix cache and suffix cache. The prefix cache helps achieve rapid parent peer searching, low startup delays, and quick responses for jump operations. The suffix cache primarily provides a scalable cache size adjustment based on the limited storage space of peers. Additionally, enhancement and compensation mechanisms are provided to reduce playback delay and more efficiently utilize limited uploading bandwidth. We also present an analytical model for determining appropriate system parameters to reduce the chunk loss probability. Experimental results show that the proposed I2CC scheme outperforms competing schemes in terms of startup delay, jump delay, and server stress under different peer arrival times and video bitrates.

A Control-Theoretic Approach for Dynamic Adaptive Video Streaming over HTTP

User-perceived quality-of-experience (QoE) is critical in Internet video applications as it impacts revenues for content providers and delivery systems. Given that there is little support in the network for optimizing such measures, bottlenecks could occur anywhere in the delivery system. Consequently, a robust bitrate adaptation algorithm in client-side players is critical to ensure good user experience. Previous studies have shown key limitations of state-of-art commercial solutions and proposed a range of heuristic fixes. Despite the emergence of several proposals, there is still a distinct lack of consensus on: (1) How best to design this client-side bitrate adaptation logic (e.g., use rate estimates vs. buffer occupancy); (2) How well specific classes of approaches will perform under diverse operating regimes (e.g., high throughput variability); or (3) How do they actually balance different QoE objectives (e.g., startup delay vs. rebuffering). To this end, this paper makes three key technical contributions. First, to bring some rigor to this space, we develop a principled control-theoretic model to reason about a broad spectrum of strategies. Second, we propose a novel model predictive control algorithm that can optimally combine throughput and buffer occupancy information to outperform traditional approaches. Third, we present a practical implementation in a reference video player to validate our approach using realistic trace-driven emulations.

A conceptual framework for dynamic extension of the red clearance interval as a countermeasure for red-light-running

This manuscript describes the development and evaluation of a conceptual framework for real-time operation of dynamic on-demand extension of the red clearance interval as a countermeasure for red-light-running. The framework includes a decision process for determining, based on the real-time status of vehicles arriving at the intersection, when extension of the red clearance interval should occur and the duration of each extension. A zonal classification scheme was devised to assess whether an approaching vehicle requires additional time to safely clear the intersection based on the remaining phase time, type of vehicle, current speed, and current distance from the intersection. Expected performance of the conceptual framework was evaluated through modeling of replicated field operations using vehicular event data collected as part of this research. The results showed highly accurate classification of red-light-running vehicles needing additional clearance time and relatively few false extension calls from stopping vehicles, thereby minimizing the expected impacts to signal and traffic operations. Based on the recommended parameters, extension calls were predicted to occur once every 26.5cycles. Assuming a 90scycle, 1.5 extensions per hour were expected per approach, with an estimated extension time of 2.30s/h. Although field implementation was not performed, it is anticipated that long-term reductions in targeted red-light-running conflicts and crashes will likely occur if red clearance interval extension systems are implemented at locations where start-up delay on the conflicting approach is generally minimal, such as intersections with lag left-turn phasing.

HLPSP: A Hybrid Live P2P Streaming Protocol

The efficiency of live Peer-to-Peer (P2P) streaming protocols depends on the appropriateness and the management abilities of their underlying overlay multicast. While a tree overlay structure confines transmission delays efficiently by maintaining deterministic delivery paths, an overlay mesh structure provides adequate resiliency to peers dynamics and easy maintenance. On the other hand, content freshness, playback fluidity and streaming continuity are still challenging issues that require viable solutions. In this paper, we propose a Hybrid Live P2P Streaming Protocol (HLPSP) based on a hybrid overlay multicast that integrates the efficiency of both the tree and mesh structures. Extensive simulations using OMNET++ are conducted to investigate the efficiency of HLPSP in terms of relevant performance metrics, and position HLPSP with respect to DenaCast the enhanced version of the well-known CoolStreaming protocol. Simulation results show that HLPSP outperforms DenaCast in terms of startup delay, end-to-end delay, play-back delay and data loss.

Assessment of drug delivery devices.

For critical drug delivery, it is important to have a constant and well-known infusion rate delivered by the complete infusion set-up (pump, tubing, and accessories). Therefore, various drug delivery devices and accessories were tested in this article in terms of their infusion accuracy, start-up delay, response time, and dependency on the viscosity. These measurements were performed as part of the European funded research project MeDD. The obtained results show that the infusion accuracy of the devices is flow rate and accessory depended, especially for low flow rates. Viscosity does not have a significant impact on the flow rate accuracy.

MPVUS: A Moving Prediction Based Video Streaming Uploading Scheme over Vehicular Networks

Video streaming uploading over vehicular ad hoc networks (VANETs) can support many interesting applications. Due to the high mobility and dynamic topology of VANETs, how to support video streaming using wireless communications between vehicles and road-side access points still remains an open issue. In this paper, we propose a geographical uploading scheme, called MPVUS, which uses the moving prediction to keep the stable forwarding and reduce the high link failure probability over VANETs. The scheme also decides the AP switch opportunity by traffic flow estimation, so as to adjust the forwarding direction timely to avoid the short-sighted switch decision. Simulation results demonstrate the effectiveness of our scheme, which can achieve good performance in terms of the start-up delay, playback interruption ratio and video frame distortion.

Experimental characterization of plasma start-up using ECRH in preparation of W7-X operation

The upcoming operation of Wendelstein 7-X (W7-X) will be supported by an Electron Cyclotron Resonance Heating (ECRH) system working at 140 GHz in second harmonic at the nominal magnetic field of 2.5T. Because the optimization of the plasma breakdown is crucial to ensure a successful plasma build-up, dedicated plasma start-up experiments were performed on three stellarator/heliotron devices: Heliotron J, LHD and WEGA. Start-up behavior and dependencies on ECRH injected power, neutral gas pressure and rotational transform were obtained in X2 heating. Plasma start-up delay time decreases with the increase in ECRH input power. However, this behavior saturates when low pre-fill neutral gas pressure conditions are met. Both the delay time and the electron density are an increasing function of the gas pressure. On Heliotron J and WEGA devices, the higher the rotational transform is, the faster the start-up and the higher the plasma density are. Analysis of the temporal evolution of the plasma start-up shows that plasma start-up on stellarators is a two-step process. In addition, off-axis heating experiments are characterized by a longer plasma start-up duration compared to on-axis heating discharges. Third harmonic in X-mode has been attempted on LHD for different neutral gas puffing settings but no plasma breakdown was achieved. This multi-machine study was useful to define ECRH start-up scenarios for W7-X.

An IP-TV P2P streaming system that improves the viewing quality and confines the startup delay of regular audience

This paper investigates how a p2p television platform can take advantage of the presence of frequent channel viewers to grant them a more satisfying service than to less regular spectators, and how such privileged users can also be protected when unfavorable operating conditions manifest within the overlay. The explored idea is to learn beforehand about the users’ interests, monitoring their behavior in the recent past, in order to cluster them in groups that display different habits; then, the video chunk scheduling algorithm of the overlay is altered, with the aim of serving frequent spectators in a privileged manner, providing them with a better viewing experience and a faster access to the selected channel without overly penalizing less habitual customers. An analytical model is developed, to capture the difference in average startup delay that the proposed modifications introduce; several additional performance metrics are numerically determined, in order to thoroughly size up the performance of both groups of viewers. The obtained results show that a clear service differentiation is attained and demonstrate that, if bandwidth resources become scarce, frequent viewers are protected and still enjoy a broadcasting service of superior quality.

Central-Evaluation Neighbors Acquiring Method for P2P Streaming System

To solve the high startup delay and playback delay in P2P streaming system which are caused by peers randomly join or leave the network, we proposed a neighbors acquiring method. This paper presents the details of our neighbors acquiring method. We use tracker server to grasp the information of all nodes in the P2P network. Based on these information, tracker server could pass proper neighbor nodes to the peer node which request neighbors from tracker server through evaluation process. Some conditions are involved in the evaluation process, like node activeness, bandwidth, time nodes existing, buffer-map matching. We estimate our neighbors acquiring method through a P2P streaming system simulation. The simulation results show the P2P streaming system which uses our neighbors acquiring method has lower startup delay and playback delay than the P2P streaming system which uses random neighbors acquiring method.

Generalized connections and incentives for supporting CE devices in live streaming systems

In the modern web applications, users have assumed a prominent role by effectively contributing to the provision of some online services, such as live streaming of multimedia content. For instance, while users watch a football match or a concert through those applications, their devices may also be sharing the received content with others who are interested in the same event, defining a Peer-to-Peer (P2P) service model. The state of the art solutions for this purpose are highly dependent on the end-points and the available network bandwidth, hindering the use of some devices (e.g. phone, tablets, TVs, etc.). In this context, the Global Media Transmission Protocol (GMTP) is proposed, a cross-layer network/transport protocol that uses access routers as the end-point of a system-independent P2P network and to cache contents of servers in Content Delivery Networks (CDN). It is discussed how GMTP enables users of a variety of smart consumer electronic devices to use GMTP-based systems, as well as a technique for encouraging users to share their network resources according to the principle that the more a user’s router shares bandwidth, the more incentives a user’s router will receive from the network. The evaluation results show that GMTP can reduce the startup delay in mobile devices, while scaling the number of nodes without increasing the bandwidth consumption, independent of the device type.

PO-0710 Dosing Errors And Clinical Impact In Preterm Infants Due To Flow Rate Variability In Mult-infusion Therapy

<h3>Background and aims</h3> Almost all preterm infants on the NICU receive continuous intra-venous infusion therapy. Commonly, multiple pharmaceuticals are administered through one catheter (multi-infusion). Due to the mutual influence of infusion pumps, dosing errors can occur that may lead to adverse events. We designed an <i><i>in vitro</i></i> experiment to measure flow rate variability and dosing errors. Subsequently, possible clinical impact was investigated. <h3>Methods</h3> We conducted an n = 3 experiment with 3 syringe pumps and disposables as used in our NICU. A clinically relevant medication schedule was simulated using laser dyes as substitutes for pharmaceuticals. Real-time, inline, absorption spectrometry was used to measure dye concentrations and, subsequently, analyse flow rate variability. After changing the flow rate we registered temporary dosing errors in the parallel pumps, in addition, we registered start-up delays. A one-compartment pharmacological model was used to investigate the clinical impact of these errors. <h3>Results</h3> The significant temporary dosing errors were between 48.1% ± 12.9% and -32.5% ± 22.5% over- and under-dose respectively. Start-up delays were up to 0.71 ± 0.11 h. Our pharmacological model indicates that these dosing errors could lead to haemodynamic instability for commonly used inotropes. <h3>Conclusions</h3> Potential clinical impact includes hypertension, hypotension and intraventricular haemorrhages. We conclude that applying multi-infusion with currently used NICU infusion setups results in dosing errors with potential clinical impact. It is advised not to combine high-alert medication on a mutual lumen or line. In addition, it is advised to raise awareness about these phenomena. This study was co-funded by the EMRP.

A revised cache allocation algorithm for VoD multicast service

The Internet is replacing the traditional telephone network as the ubiquitous network infrastructure. Internet customers are increasing at an exponential rate and will continue to increase in the near future. Among the various Internet services, IPTV VoD (Video on Demand) service is expected to be one of the most popular services. In general, for deploying streamed video service, it is likely to use proxy by locating it nearby end-users. The use of proxy in on-demand media streaming service can help reduce the server streaming load and reduce the startup delay of media playback due to swift retrieval of beginning portion of media. We had proposed a cache allocation scheme for server-proxy media streaming environment by utilizing the advantage of threshold-based multicast mechanism. However it suffer from a little radical change of threshold value. In this paper, enhanced multicast-based server-proxy on-demand media streaming algorithm to IPTV VoD services is presented from the storage, caching size and bandwidth requirement viewpoints.

Advanced bootstrap and adjusted bandwidth for content distribution in peer-to-peer live streaming

Today peer-to-peer (P2P) systems have been deployed for various Internet multimedia applications such as live video streaming service. However, both peer churn and upload capacity insufficiency are inherent problems causing long start-up delay and unstable playback quality. Therefore, we introduce a scalable application-layer multicast algorithm, ABCD-P2P, which inherits the short end-to-end delay and low control overhead due to the push delivery scheme. The logical overlay is close to the physical topology (i.e., geographic proximity) in ABCD-P2P, so a short streaming multicast delivery path reduces the number of hops and avoids the network bottleneck or far routing. Both an advanced bootstrap mechanism and an adjusted bandwidth mechanism are suitable for the asymmetric bandwidth network. The mathematical analysis and simulation results demonstrate that our proposed scheme can achieve the goals of high playback smoothness, short start-up delay, short end-to-end delay, low control overhead, and short recovery time.

Effects of Countdown Signals in Red Phase on Drivers: A Comparative Study between Japan and Turkey

Countdown signals can be found in many countries; however, there are only a few researches that study the impact of the signals on driver behavior. In this study, we focus particularly on the behavior of drivers reacting to countdown signals when the signal shifted from red to green. Although the countdown signal can reduce startup delay, it also causes drivers premature start. This paper determines the factors influencing the behaviors of drivers on startup delay, premature start, and headway due to countdown signals. The analysis results are compared between Japan and Turkey. From our findings, we propose countermeasures to reduce the problems caused by the countdown signals which can be a guideline for implementation or modification of countdown-signalized intersections in many countries in order to increase safety of both drivers and pedestrians as well as drivers’ satisfactions.