Performance In Terms Of Availability Research Articles

Performance evaluation of multi service provisioning for multi-hop cooperative data dissemination in SDHVN

A large number of RSUs are deployed to improve vehicular ad-hoc networks (VANETs) in recent years. On the other hand, it leads to an increase in the cost of the network. Multi-hop cooperative data dissemination (MHCDD) protocols can reduce using RSUs. These RSUs must cope with intermittent connectivity for longer distance communication. Minimizing the RSUs increases the data traffic and end-to-end delay. Moreover, mobility management, handling the connection time between vehicles, and data traffic in VANETs are challenging tasks in dense networks. In this context, we proposed a multi-hop cooperative data dissemination technique using a virtual network functioning and software-defined network-enable on the heterogeneous vehicular network (SDHVN). The problem of packet scheduling on the buffer occupancy is solved using an enhanced periodic update (ePU) and enhancing event-driven deadline (eEDD). The results illustrate the proposed algorithm’s significant performance in terms of availability with the limited wireless channels. The queueing models adopted for optimizing the load balancing are by using the mobile edge controller. These queueing model minimizes the latency and maximizes network utility.

Learning Spatiotemporal Failure Dependencies for Resilient Edge Computing Services

Edge computing services are exposed to infrastructural failures due to geographical dispersion, ad hoc deployment, and rudimentary support systems. Two unique characteristics of the edge computing paradigm necessitate a novel failure resilience approach. First, edge servers, contrary to cloud counterparts with reliable data center networks, are typically connected via ad hoc networks. Thus, link failures need more attention to ensure truly resilient services. Second, network delay is a critical factor for the deployment of edge computing services. This restricts replication decisions to geographical proximity and necessitates joint consideration of delay and resilience. In this article, we propose a novel machine learning based mechanism that evaluates the failure resilience of a service deployed redundantly on the edge infrastructure. Our approach learns the spatiotemporal dependencies between edge server failures and combines them with the topological information to incorporate link failures. Ultimately, we infer the probability that a certain set of servers fails or disconnects concurrently during service runtime. Furthermore, we introduce Dependency- and Topology-aware Failure Resilience (DTFR), a two-stage scheduler that minimizes either failure probability or redundancy cost, while maintaining low network delay. Extensive evaluation with various real-world failure traces and workload configurations demonstrate superior performance in terms of availability, number of failures, network delay, and cost with respect to the state-of-the-art schedulers.

Reliability assessment of solar photovoltaic systems based on fuzzy fault tree analysis

Solar photovoltaic (SPV) systems are widely used as a renewable energy source to produce electricity to endusers. SPV system convert free and unlimited sunlight into electricity without carbon dioxide emission or any other air pollutants. The stochastic nature of SPV system may be responsible for degradation of performance in terms of availability, production, etc. Therefore, the assessment of the performance measures like reliability and quality of its components is vital concern that may open the new vista of research. There are various reliability assessment techniques used in conventional (thermal power plant, hydropower plant, nuclear power plant, etc.) and non-conventional power system (SPV power plant, wind power plant, etc.) like Fault Tree Analysis (FTA), Failure Mode and Effect Analysis (FMEA), etc. FTA is one of the powerful reliability assessment techniques, which gives modes of the failure and its consequences, that are demonstrated on SPV systems. FTA can further be broadly classified into two: qualitative and quantitative analysis. Qualitative FTA can be solved by determining a minimal cut set (MCS) and quantitative FTA can be solved by calculating the failure probability of each the basic event. In conventional FTA failure probability of each event must be known, to assess for quantitative FTA. However, to quantify probabilistic failure, data of all basic events seem to be inadequate. To overcome this problem, conventional FTA may be integrated with fuzzy linguistic scale method. In this research work, failure possibilities in terms of a linguistic variable of unknown failure data for all basic events, which lead the Top Events for SPV systems are assigned by the experts from academics, research, industries and practicing engineers. For Aggregated fuzzy number based on expert’s opinion, a consistency agreements method is used. Fussell-Vesely (F-V) importance measures is also implemented to rank the basic events and MCS to apportion the most critical event.

A new method for incorporating polyethyleneimine (PEI) in algal beads: High stability as sorbent for palladium recovery and supported catalyst for nitrophenol hydrogenation

The incorporation of glutaraldehyde crosslinked polyethylenimine (PEI) in algal beads (ABA/PEI) increases its Pd(II) sorption capacity. However, the large size of dispersed agglomerates introduces limitations of sorption performance in terms of availability and accessibility of reactive groups. The homogeneous incorporation of PEI in alginate/algal mixture prior to inotropic gelation and glutaraldehyde crosslinking (HABA/PEI) improves sorption performance: HABA/PEI beads have a higher maximum sorption capacity (1.49 ± 0.02 mmol g−1) than ABA/PEI (1.13 ± 0.03 mmol g−1), probably due to more uniform dispersion of PEI in HABA/PEI beads. The comparison of 5 consecutive cycles of sorption-desorption shows that HABA/PEI beads are physically stable with no mass loss, while ABA/PEI bead loses up to 30% of its weight. The potential of these materials as precursors for the synthesis of supported catalysts has been investigated. Pd(II) sorbed on ABA/PEI and HABA/PEI has been reduced to Pd(0) using hydrazine hydrate or hydrogen gas (generated in situ). A simple hydrogenation reaction of 3-nitrophenol (with sodium formate as hydrogen donor) was tested for comparing their catalytic properties. Catalytic tests show that HABA catalyst exhibits similar catalytic activity, but better stability and reusability compared with ABA catalyst. Their rate constants are lower than conventional nanostructured catalysts, probably due to intra-diffusion limitation.

Implementation of IP Video Streaming Software to Identify Availability and Audience

Abstract: The perpetual rise of the video on demand is currently one of the leading challenges the telecommunications industry faces. It per passes the eternal comparison with a service that continuously set?s the bar at a highly elevated consumer quality. And the user, advertiser and all stakeholders involved not only are used to it, but demand equal and/or similar value, i.e., Broadcast Television. Such dichotomy has made this relatively new medium create a long list of technologies to make this as viable as possible. However, the solutions only work to a certain extent and critical problems remain not yet addressed. One in particular is delivery assurance in Internet Protocol networks, which affects every stakeholder on these New Media outlets. Keeping this issue in mind, this work developed a range of experiment scenarios through a software-based apparatus in order to convey a technical assessment of key variables in this ecosystem. Afterwards, from these tests an analysis was conducted which brought about a series of discoveries in regards to the technology performance in terms of availability and audience. Ultimately, it culminated in one the central contributions of this research, that is, how to mathematically interpret this type of data indicating its statistical relations. Such methods unveiled impacts and feasibility of: Privacy protocols, mobile and landline connection, latency, delay, loading time, interactions volumes, content history, channel characteristics and user attributes. In other words, this work developed a tool to measure audience and availability in IP delivery. And, it also forged a method to interpret and model the measurements into statistical patterns that can provide predictability. Additionally, it is stated that the significance of this research was confirmed through the Law of Large Numbers, which showed that the data has statistical validity to interpret and envision behavior. That is, the work presents data with a reliability of 97% with a margin of error of 3.03% which confirms this, to the best of our knowledge, as the most comprehensive accurate study of this nature in comparison to the state of the art in the literature. It is also necessary to ascertain that the tool is restricted to measuring quantities related to each content displayed for the largest platform of online video and the most desktop utilized Web Browser, i.e., YouTube and Google Chrome.

Tightly-Coupled Integration of Multi-GNSS Single-Frequency RTK and MEMS-IMU for Enhanced Positioning Performance.

Dual-frequency Global Positioning System (GPS) Real-time Kinematics (RTK) has been proven in the past few years to be a reliable and efficient technique to obtain high accuracy positioning. However, there are still challenges for GPS single-frequency RTK, such as low reliability and ambiguity resolution (AR) success rate, especially in kinematic environments. Recently, multi-Global Navigation Satellite System (multi-GNSS) has been applied to enhance the RTK performance in terms of availability and reliability of AR. In order to further enhance the multi-GNSS single-frequency RTK performance in terms of reliability, continuity and accuracy, a low-cost micro-electro-mechanical system (MEMS) inertial measurement unit (IMU) is adopted in this contribution. We tightly integrate the single-frequency GPS/BeiDou/GLONASS and MEMS-IMU through the extended Kalman filter (EKF), which directly fuses the ambiguity-fixed double-differenced (DD) carrier phase observables and IMU data. A field vehicular test was carried out to evaluate the impacts of the multi-GNSS and IMU on the AR and positioning performance in different system configurations. Test results indicate that the empirical success rate of single-epoch AR for the tightly-coupled single-frequency multi-GNSS RTK/INS integration is over 99% even at an elevation cut-off angle of 40°, and the corresponding position time series is much more stable in comparison with the GPS solution. Besides, GNSS outage simulations show that continuous positioning with certain accuracy is possible due to the INS bridging capability when GNSS positioning is not available.

Physical Layer Definition for a Long-Haul HF Antarctica to Spain Radio Link

La Salle and the Observatori de l’Ebre (OE) have been involved in a remote sensing project in Antarctica for the last 11 years. The OE has been monitoring the geomagnetic activity for more than twenty years and also the ionospheric activity of the last ten years in the Spanish Antarctic Station Juan Carlos I (ASJI) (62.7 ° S, 299.6 ° E). La Salle is finishing the design and testing of a low-power communication system between the ASJI and Cambrils (41.0 ° N, 1.0 ° E) with a double goal: (i) the transmission of data from the sensors located at the ASJI and (ii) the performance of an oblique ionospheric sounding of a 12,760 km HF link. Previously, La Salle has already performed sounding and modulation tests to describe the channel performance in terms of availability, Signal-to-Noise Ratio (SNR), Doppler spread and delay spread. This paper closes the design of the physical layer, by means of the channel error study and the synchronization performance, and concludes with a new physical layer proposal for the Oblique Ionosphere Sounder. Narrowband and wideband frames have been defined to be used when the oblique sounder performs as an ionospheric sensor. Finally, two transmission modes have been defined for the modem performance: the High Robustness Mode (HRM) for low SNR hours and the High Throughput Mode (HTM) for the high SNR hours.

Performance modeling and optimization for the stock preparation unit of a paper plant using genetic algorithm

PurposeThis paper aims to deal with the performance modeling and optimization for the stock preparation unit of a paper plant using genetic algorithm. It provides the optimum unit availability level for different combinations of failure and repair rates of the subsystems of the stock preparation unit of the paper plant concerned.Design/methodology/approachEfforts have been made to develop the performance model based on a real situation for the stock preparation unit. The performance in terms of availability has been evaluated on the basis of Markov birth‐death process. After that, the performance optimization using genetic algorithm is performed, which gives the optimum unit availability levels for different combinations of failure and repair rates of the subsystems of stock preparation unit for enhancing the overall performance of the paper plant.FindingsThe effect of genetic algorithm parameters such as number of generations, population size and crossover probability on the unit performance, i.e. availability, has been analyzed and discussed with the concerned paper plant management. It is found that these results are highly beneficial to the maintenance engineers for the purpose of the effective maintenance planning to enhance the overall performance (availability) of stock preparation unit of the paper plant.Originality/valueMost other researchers have confined their work to the development and analysis of theoretical models which has little practical significance. To fulfill this deficiency, efforts have been made in the present work to develop a model based on real situation for stock preparation unit.

Fusion of Onboard Sensors for Better Navigation

This paper presents simulation results of navigation sensors such as integrated navigation system (INS), global navigation satellite system (GNSS) and TACAN sensors onboard an aircraft to find the navigation solutions. Mathematical models for INS, GNSS (GPS) satellite trajectories, GPS receiver and TACAN characteristics are simulated in Matlab. The INS simulation generates the output for position, velocity and attitude based on aerosond dynamic model. The GPS constellation is generated based on the YUMA almanac data. The GPS dilution of precession (DOP) parameters are calculated and the best combination of four satellites (minimum PDOP) is used for calculating the user position and velocity. The INS, GNSS, and TACAN solutions are integrated through loosely coupled extended Kalman filter for calculating the optimum navigation solution. The work is starting stone for providing aircraft based augmentation system for required navigation performance in terms of availability, accuracy, continuity and integrity. Defence Science Journal, 2013, 63(2), pp.145 -152 , DOI:http://dx.doi.org/10.14429/dsj. 63.4256

Performance modeling and optimization for the stock preparation unit of a paper plant using genetic algorithm

PurposeThe purpose of this paper is to deal with the performance modeling and optimization for the stock preparation unit of a paper plant using genetic algorithm. It provides the optimum unit availability level for different combinations of failure and repair rates of the subsystems of the stock preparation unit of the paper plant concerned.Design/methodology/approachIn this paper, efforts have been made to develop performance models based on real situations for the stock preparation unit. The performance in terms of availability has been evaluated on the basis of Markov birth‐death process. After that, the performance optimization using genetic algorithm is done, which gives the optimum unit availability levels for different combinations of failure and repair rates of the subsystems of stock preparation units for enhancing the overall performance of the paper plant.FindingsThe effect of genetic algorithm parameters, namely number of generations, population size and crossover probability on the unit performance i.e. availability has been analyzed and discussed with the concerned paper plant management. It is found that these results are highly beneficial to the maintenance engineers for the purpose of effective maintenance planning to enhance the overall performance (availability) of the stock preparation unit of the paper plant.Originality/valueMost of the researchers have confined their work to the development and analysis of theoretical models which has little practical significance. To fulfill this deficiency, efforts have been made in the present work to develop a model based on real situations for the stock preparation unit.

P-cycle Protection in multi-domain optical networks

Providing resilient inter-domain connections in multi-domain optical GMPLS networks is a challenge. On the one hand, the integration of different GMPLS domains to run traffic engineering operations requires the development of a framework for inter-domain routing and control of connections, while keeping the internal structure and available resources of the domains undisclosed to the other operators. On the other hand, the definition of mechanisms to take advantage of such automatically switched inter-domain connectivity is still an open issue. This article focuses on the analysis of applicability of one of these mechanisms: P-cycle-based protection. The proposed solution is based on the decomposition of the multi-domain resilience problem into two sub-problems, namely, the higher level inter-domain protection and the lower level intra-domain protection. Building a P-cycle at the higher level is accomplished by certain tasks at the lower level, including straddling link connection, capacity allocation and path selection. In this article, we present several methods to realize inter-domain P-cycle protection at both levels and we evaluate their performance in terms of availability and spent resources. A discussion on a proposal of implementation of signalling based on extensions of existing protocols such as RSVP-TE and the PCE architecture illustrates the practical viability of the approach.