scholarly journals Performability Evaluation of Voice Services in Converged Networks

2020 ◽  
Vol 27 (4) ◽  
pp. 11-19
Author(s):  
Almir Pereira Guimarães ◽  
Dênis Da Silva Rodrigues ◽  
Bruno Costa e Silva Nogueira
Keyword(s):  
Block Diagram ◽  
Discrete Event ◽  
Stochastic Petri Nets ◽  
Data Traffic ◽  
Network Resources ◽  
Acceptable Quality ◽  
Quality Of Voice ◽  
Warm Standby ◽  
Higher Sensitivity

In the last years, the transmission of voice services in converged networks has experienced a huge growth. However, there are still some questions considering the ability of these networks to deliver voice services with acceptable quality. In this paper, we applied analytical modeling and simulation to analyze the quality of voice services using a new index, called MOS a , which considers jointly the MOS index and the availability of the subjacent infrastructure. We consider the influence of different CODECs (G.711 and G.729), queuing policies (Priority Queuing and Custom Queuing), and the warm standby redundancy mechanism. Our goal is to analyze the quality of these services by taking into account overloading conditions in different  architectures/scenarios. These scenarios were constructed using the modeling mechanisms Reliability Block Diagram and Stochastic Petri Nets in addition to a discrete event simulator. Experimental results indicate that the G.711 CODEC has a higher sensitivity both in terms of data traffic volume and allocated network resources in relation to the G.729 CODEC.

scholarly journals A Bursts Contention Avoidance Scheme Based on Streamline Effect Awareness and Limited Intermediate Node Buffering in the Core Network

2020 ◽  
Vol 9 (6) ◽  
pp. 124-134
Keyword(s):  
Performance Comparison ◽  
Core Network ◽  
Network Resources ◽  
Intermediate Node ◽  
Control Packet ◽  
Data Packets ◽  
Acceptable Quality ◽  
Offset Time ◽  
Data Burst

In an Optical Burst Switched (OBS) network, data packets sourced from peripheral networks are assembled into huge sized data bursts. For each assembled data burst, an associated control signal in the form of a burst control packet is (BCP) is generated and scheduled at an offset time ahead of the data burst. The offset timing is to allow for the pre-configuration of required resources at all subsequent intermediate nodes prior to the actual data burst’s arrival. In that way, the data burst will fly-by each node and hence no requirement for temporary buffering at all intermediate nodes. An operational requirement of an OBS network is that it be loss-less as in that way a consistent as well as acceptable quality of service (QoS) for all applications and services it serves as a platform can be guaranteed. Losses in such a network are mainly caused by improper provisioning as well as dimensioning of resources thus leading to contentions among bursts and consequently discarding of some of the contending data bursts. Key to both provisioning as well as proper dimensioning of the available resources in an optimized way is the implementation of effective routing and wavelength (RWA) that will seclude any data losses due to contention occurrences. On the basis of the effects of the streamline effect (SLE), that is, effectively secluding primary contention among flows (streams) in the network, we propose in this paper a limited intermediate buffering that couples with SLE aware prioritized RWA (LIB-PRWA) scheme that combats secondary contention as well. The scheme makes routing decisions such as selection of primary and deflection routes based on current resources states in the candidate paths. A performance comparison of the proposed scheme is carried out and simulation results demonstrate its comparative abilities to effectively reduce losses as well as maintaining both high network resources utilization as well as QoS.

Introduction

2010 ◽  
pp. 1-13 ◽  
Author(s):  
Sasan Adibi ◽  
Raj Jain ◽  
Shyam Parekh ◽  
Bell Labs
Keyword(s):  
Wireless Networks ◽  
Quality Of Service ◽  
User Experience ◽  
Quality Of Experience ◽  
Mobile Services ◽  
Network Resources ◽  
Acceptable Quality ◽  
New Challenges

Emergence of all IP based wired and wireless networks for mobile services, calls for new innovations and architectural approaches. Coexistence of legacy and emerging networks such as different generations of networks based on 3GPP and 3GPP2 specifications, Wi-Fi and WiMAX, have posed new challenges to guarantee acceptable Quality of Experience (QoE) to the users. Different user environments such as fixed, nomadic, and vehicular have brought about new Quality of Service (QoS) practices and have introduced policies to best optimize the network resources and enhance user experience.

scholarly journals Manufacturing and development of a bolted GFRP flange joint for oil and gas applications

2021 ◽  
pp. 095440542198951
Author(s):  
Muhsin Aljuboury ◽  
Md Jahir Rizvi ◽  
Stephen Grove ◽  
Richard Cullen
Keyword(s):  
Pressure Vessel ◽  
Oil And Gas ◽  
Polyester Resin ◽  
High Strength ◽  
Adhesively Bonded ◽  
Acceptable Quality ◽  
Composite Pipe ◽  
And Performance ◽  
Composite Pipes

The goal of this experimental study is to manufacture a bolted GFRP flange connection for composite pipes with high strength and performance. A mould was designed and manufactured, which ensures the quality of the composite materials and controls its surface grade. Based on the ASME Boiler and Pressure Vessel Code, Section X, this GFRP flange was fabricated using biaxial glass fibre braid and polyester resin in a vacuum infusion process. In addition, many experiments were carried out using another mould made of glass to solve process-related issues. Moreover, an investigation was conducted to compare the drilling of the GFRP flange using two types of tools; an Erbauer diamond tile drill bit and a Brad & Spur K10 drill. Six GFRP flanges were manufactured to reach the final product with acceptable quality and performance. The flange was adhesively bonded to a composite pipe after chamfering the end of the pipe. Another type of commercially-available composite flange was used to close the other end of the pipe. Finally, blind flanges were used to close both ends, making the pressure vessel that will be tested under the range of the bolt load and internal pressure.

scholarly journals A Highly Effective Route for Real-Time Traffic Using an IoT Smart Algorithm for Tele-Surgery Using 5G Networks

2021 ◽  
Vol 10 (2) ◽  
pp. 30
Author(s):  
Radwan S. Abujassar ◽  
Husam Yaseen ◽  
Ahmad Samed Al-Adwan
Keyword(s):  
Live Streaming ◽  
Data Traffic ◽  
Data Packets ◽  
Real Time Traffic ◽  
Medical Quality ◽  
Optimal Smoothing ◽  
Patient Will ◽  
Three Stages ◽  
Exchange Data

Nowadays, networks use many different paths to exchange data. However, our research will construct a reliable path in the networks among a huge number of nodes for use in tele-surgery using medical applications such as healthcare tracking applications, including tele-surgery which lead to optimizing medical quality of service (m-QoS) during the COVID-19 situation. Many people could not travel due to the current issues, for fear of spreading the covid-19 virus. Therefore, our paper will provide a very trusted and reliable method of communication between a doctor and his patient so that the latter can do his operation even from a far distance. The communication between the doctor and his/her patient will be monitored by our proposed algorithm to make sure that the data will be received without delay. We test how we can invest buffer space that can be used efficiently to reduce delays between source and destination, avoiding loss of high-priority data packets. The results are presented in three stages. First, we show how to obtain the greatest possible reduction in rate variability when the surgeon begins an operation using live streaming. Second, the proposed algorithm reduces congestion on the determined path used for the online surgery. Third, we have evaluated the affection of optimal smoothing algorithm on the network parameters such as peak-to-mean ratio and delay to optimize m-QoS. We propose a new Smart-Rout Control algorithm (s-RCA) for creating a virtual smart path between source and destination to transfer the required data traffic between them, considering the number of hops and link delay. This provides a reliable connection that can be used in healthcare surgery to guarantee that all instructions are received without any delay, to be executed instantly. This idea can improve m-QoS in distance surgery, with trusted paths. The new s-RCA can be adapted with an existing routing protocol to track the primary path and monitor emergency packets received in node buffers, for direct forwarding via the demand path, with extended features.

scholarly journals Adaptive Reservation of Network Resources According to Video Classification Scenes

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 1949
Author(s):  
Lukas Sevcik ◽  
Miroslav Voznak
Keyword(s):  
User Satisfaction ◽  
Quality Evaluation ◽  
Spatial Information ◽  
Service Providers ◽  
Video Quality ◽  
Subjective Assessment ◽  
Video Sequences ◽  
Network Resources ◽  
Proposed Model

Video quality evaluation needs a combined approach that includes subjective and objective metrics, testing, and monitoring of the network. This paper deals with the novel approach of mapping quality of service (QoS) to quality of experience (QoE) using QoE metrics to determine user satisfaction limits, and applying QoS tools to provide the minimum QoE expected by users. Our aim was to connect objective estimations of video quality with the subjective estimations. A comprehensive tool for the estimation of the subjective evaluation is proposed. This new idea is based on the evaluation and marking of video sequences using the sentinel flag derived from spatial information (SI) and temporal information (TI) in individual video frames. The authors of this paper created a video database for quality evaluation, and derived SI and TI from each video sequence for classifying the scenes. Video scenes from the database were evaluated by objective and subjective assessment. Based on the results, a new model for prediction of subjective quality is defined and presented in this paper. This quality is predicted using an artificial neural network based on the objective evaluation and the type of video sequences defined by qualitative parameters such as resolution, compression standard, and bitstream. Furthermore, the authors created an optimum mapping function to define the threshold for the variable bitrate setting based on the flag in the video, determining the type of scene in the proposed model. This function allows one to allocate a bitrate dynamically for a particular segment of the scene and maintains the desired quality. Our proposed model can help video service providers with the increasing the comfort of the end users. The variable bitstream ensures consistent video quality and customer satisfaction, while network resources are used effectively. The proposed model can also predict the appropriate bitrate based on the required quality of video sequences, defined using either objective or subjective assessment.

Exploration and Practice about Bilingual Teachers and the Network Resources Construction for Data Structure

2013 ◽  
Vol 694-697 ◽  
pp. 3675-3679
Author(s):  
Yi Xiang ◽  
Jun Peng ◽  
Qian Xiong ◽  
Liang Lei ◽  
Ming Ying You
Keyword(s):  
Data Structure ◽  
Bilingual Teachers ◽  
Network Resources ◽  
Network Teaching ◽  
Qualified Teachers ◽  
Teaching Platform ◽  
Bilingual Teaching ◽  
Resource Library ◽  
Poor Teaching

Targeting at the "Data Structure" bilingual classes with regard to the lack of qualified teachers, a sharp learning curve and the poor teaching effect that are widespread in colleges and universities, this paper gives an analysis in an attempt to find a solution to the issue on quality of teachers, by means of the development of a network teaching platform and a supporting resource library for carrying out high-quality bilingual teaching.

ASSESSMENT OF THE APPLICABILITY OF LARAWAN TECHNOLOGIES FOR THE ORGANIZATION OF A BACKUP COMMUNICATION CHANNEL FOR METEOROLOGICAL SUPPORT OF AIRFIELDS

2021 ◽  
pp. 25-31
Author(s):  
Д.К. Тунеголовец
Keyword(s):  
Communication Channel ◽  
Block Diagram ◽  
Essential Feature ◽  
Spatial And Temporal Variability ◽  
Weather Forecasts ◽  
Economic Problems ◽  
Present Information ◽  
The Cost ◽  
Positive Results

В настоящее время информация о состоянии атмосферы широко используется как при составлении прогнозов погоды, так и при решении многих экономических задач. Существенная особенность метеорологических явлений - их пространственно-временная изменчивость. Это вызывает необходимость такой организации наблюдений, которая позволит своевременно отметить возникновение явления и проследить за ходом его развития. Статистика показывает, что в период с 1997 по 2000 годы произошло порядка 193 авиационных инцидентoв, которые обусловлены недостатками метеорологического обеспечения полетов. Поэтому задача повышения качества метеорологического обеспечения является актуальной. На основе модельных и практических экспериментов показано, что беспроводной канал связи LoRaWaN способен объединить весь поток данных, поступающих с удаленных метеорологических датчиков, которые используют разные протоколы для взаимодействия друг с другом. В ходе выполнения эксперимента получены положительные результаты, доказывающие возможность организации таких каналов связи для задач метеообеспечения аэродромов. Также приводится структурная схема для организации канала связи. При этом не требуется прокладка кабельных коммуникаций связи, когда стоимость такого вида работ, включая согласование, зачастую значительно превышает стоимость самого метеорологического оборудования At present, information on the state of the atmosphere is widely used both in the preparation of weather forecasts and in solving many economic problems. An essential feature of meteorological phenomena is their spatial and temporal variability. This makes it necessary to organize observations in such a way that will allow timely noting the occurrence of the phenomenon and monitoring the progress of its development. Statistics show that in the period from 1997 to 2000 there were about 193 aviation incidents, which were caused by shortcomings in the meteorological support of flights. Therefore, the task of improving the quality of meteorological support is urgent. This article shows, based on model and practical experiments, that the LaRaWAN wireless communication channel is able to combine the entire data stream coming from remote meteorological sensors using various communication protocols among themselves. During the experiment, I obtained positive results, proving the possibility of organizing such communication channels for the tasks of meteorological support of airfields. A block diagram for the organization of a communication channel is also provided. At the same time, the laying of cable communications is not required, when the cost of this type of work, including coordination, often significantly exceeds the cost of the meteorological equipment itself

TESTING AND FORMAL VERIFICATION OF SERVICE ORIENTED ARCHITECTURES

2009 ◽  
Vol 16 (02) ◽  
pp. 137-162 ◽  
Author(s):  
JOHN C. SLOAN ◽  
TAGHI M. KHOSHGOFTAAR
Keyword(s):  
Formal Verification ◽  
Software Agents ◽  
Third Party ◽  
Software Quality Assurance ◽  
Middle Ground ◽  
Network Resources ◽  
Service Oriented Architectures ◽  
Engineering Problems ◽  
Service Oriented

We examine two open engineering problems in the area of testing and formal verification of internet-enabled service oriented architectures (SOA). The first involves deciding when to formally and exhaustively verify versus when to informally and non-exhaustively test. The second concerns scalability limitations associated with formal verification, to which we propose a semi-formal technique that uses software agents. Finally, we assess how these findings can improve current software quality assurance practices. Addressing the first problem, we present and explain two classes of tradeoffs. External tradeoffs between assurance, performance, and flexibility are determined by the business needs of each application, whether it be in engineering, commerce, or entertainment. Internal tradeoffs between assurance, scale, and level of detail involve the technical challenges of feasibly verifying or testing an SOA. To help decide whether to exhaustively verify or non-exhaustively test, we present and explain these two classes of tradeoffs. Identifying a middle ground between testing and verification, we propose using software agents to simulate services in a composition. Technologically, this approach has the advantage of assuring the quality of compositions that are too large to exhaustively verify. Operationally, it supports testing these compositions in the laboratory without access to source code or use of network resources of third-party services. We identify and exploit the structural similarities between agents and services, examining how doing so can assure the quality of service compositions.

Storage Life of Refrozen Silver Hake (Merluccius bilinearis) Processed as Fillets am Minced Flesh from Thawed, Stored, Round-Frozen Fish

1977 ◽  
Vol 34 (12) ◽  
pp. 2369-2373 ◽  
Author(s):  
Doris Fraser Hiltz ◽  
D. H. North ◽  
Barbara Smith Lall ◽  
R. A. Keith
Keyword(s):  
Key Words ◽  
Frozen Storage ◽  
Storage Life ◽  
Freeze Thaw ◽  
Acceptable Quality ◽  
Frozen Fish ◽  
Silver Hake ◽  
Merluccius Bilinearis ◽  
Protein Extractability

Refrozen silver hake (Merluccius bilinearis), processed as fillets and minced flesh after thawing of stored round fish that had been frozen within 14 h of capture, underwent rapid deterioration during storage at −18 °C compared with once-frozen control materials from the same lot of fish. The estimated maximum storage life of silver hake refrozen as fillets after 3 and 6 mo storage of the round fish at −25 °C was reduced to about 4.5 and 1 mo, respectively, from 10 mo for once-frozen control fillets. Quality of the refrozen materials immediately after thawing and refreezing was similar to that of the round-frozen fish, except after 6 mo, where some initial deterioration occurred, particularly in minced flesh. Minced flesh was more unstable in frozen storage than fillets. In all once- and twice-frozen materials, formation of dimethylamine occurred concomitantly with decrease in protein extractability. Round-frozen fish underwent no loss in protein extractability during 6 mo storage at −25 °C, but some lipid hydrolysis occurred. These results suggest that the freeze–thaw–refreeze process as applied to silver hake will yield a final product of acceptable quality provided that storage of the round fish does not exceed 3–4 mo and that the refrozen materials are marketed within a month after processing. Key words: silver hake, Merluccius bilinearis, refrozen storage, dimethylamine, minced flesh

scholarly journals Modelling and Performance Analysis of Electric Car-Sharing Systems Using Petri Nets

2020 ◽  
Vol 170 ◽  
pp. 03001 ◽  
Author(s):  
A. Hamroun ◽  
K. Labadi ◽  
M. Lazri
Keyword(s):  
Petri Nets ◽  
Simulation Analysis ◽  
Discrete Event ◽  
Stochastic Petri Nets ◽  
Car Sharing ◽  
Event Simulation ◽  
Electric Car ◽  
Bike Sharing ◽  
And Performance ◽  
Charging Stations

Car sharing systems emerged as a new answer to mobility challenges in smart and sustainable cities. Despite their apparent success, design and exploitation of such systems raise crucial strategic and operational challenges. To help planners and decision makers, simulation, analysis and optimization models are unavoidable. Based on the formal modelling and analysis power of stochastic Petri nets, this paper proposes a discrete event simulation model for electric car sharing systems for performance and analysis purposes, taking into account their complex dynamic behaviour, organization and parameters including capacities of the stations, battery and energy availability, locations of charging stations and also their car maintenance activities, not negligible compared to the case of bike-sharing systems.

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